Consolidate _swrast_write_texture_span() into _swrast_write_rgba_span().
[mesa.git] / src / mesa / swrast / s_tritemp.h
index 0dc4f891820bd6d9ecbcd94470d362d9d3a6bb07..c09f1eddf0db0c7e2a0f3108991a83a42272cc6a 100644 (file)
@@ -1,10 +1,8 @@
-/* $Id: s_tritemp.h,v 1.42 2003/01/14 04:55:46 brianp Exp $ */
-
 /*
  * Mesa 3-D graphics library
- * Version:  5.1
+ * Version:  6.1
  *
- * Copyright (C) 1999-2002  Brian Paul   All Rights Reserved.
+ * Copyright (C) 1999-2004  Brian Paul   All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -23,7 +21,6 @@
  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-/* $XFree86: xc/extras/Mesa/src/swrast/s_tritemp.h,v 1.2 2002/02/27 21:07:54 tsi Exp $ */
 
 /*
  * Triangle Rasterizer Template
@@ -32,7 +29,8 @@
  *
  * The following macros may be defined to indicate what auxillary information
  * must be interplated across the triangle:
- *    INTERP_Z        - if defined, interpolate Z values
+ *    INTERP_Z        - if defined, interpolate vertex Z values
+ *    INTERP_W        - if defined, interpolate vertex W values
  *    INTERP_FOG      - if defined, interpolate fog values
  *    INTERP_RGB      - if defined, interpolate RGB values
  *    INTERP_ALPHA    - if defined, interpolate Alpha values (req's INTERP_RGB)
@@ -43,8 +41,6 @@
  *    INTERP_TEX      - if defined, interpolate set 0 float STRQ texcoords
  *                         NOTE:  OpenGL STRQ = Mesa STUV (R was taken for red)
  *    INTERP_MULTITEX - if defined, interpolate N units of STRQ texcoords
- *    INTERP_FLOAT_RGBA - if defined, interpolate RGBA with floating point
- *    INTERP_FLOAT_SPEC - if defined, interpolate specular with floating point
  *
  * When one can directly address pixels in the color buffer the following
  * macros can be defined and used to compute pixel addresses during
  * This code was designed for the origin to be in the lower-left corner.
  *
  * Inspired by triangle rasterizer code written by Allen Akin.  Thanks Allen!
+ *
+ *
+ * Some notes on rasterization accuracy:
+ *
+ * This code uses fixed point arithmetic (the GLfixed type) to iterate
+ * over the triangle edges and interpolate ancillary data (such as Z,
+ * color, secondary color, etc).  The number of fractional bits in
+ * GLfixed and the value of SUB_PIXEL_BITS has a direct bearing on the
+ * accuracy of rasterization.
+ *
+ * If SUB_PIXEL_BITS=4 then we'll snap the vertices to the nearest
+ * 1/16 of a pixel.  If we're walking up a long, nearly vertical edge
+ * (dx=1/16, dy=1024) we'll need 4 + 10 = 14 fractional bits in
+ * GLfixed to walk the edge without error.  If the maximum viewport
+ * height is 4K pixels, then we'll need 4 + 12 = 16 fractional bits.
+ *
+ * Historically, Mesa has used 11 fractional bits in GLfixed, snaps
+ * vertices to 1/16 pixel and allowed a maximum viewport height of 2K
+ * pixels.  11 fractional bits is actually insufficient for accurately
+ * rasterizing some triangles.  More recently, the maximum viewport
+ * height was increased to 4K pixels.  Thus, Mesa should be using 16
+ * fractional bits in GLfixed.  Unfortunately, there may be some issues
+ * with setting FIXED_FRAC_BITS=16, such as multiplication overflow.
+ * This will have to be examined in some detail...
+ *
+ * For now, if you find rasterization errors, particularly with tall,
+ * sliver triangles, try increasing FIXED_FRAC_BITS and/or decreasing
+ * SUB_PIXEL_BITS.
  */
 
-
 /*
- * This is a bit of a hack, but it's a centralized place to enable floating-
- * point color interpolation when GLchan is actually floating point.
+ * ColorTemp is used for intermediate color values.
  */
 #if CHAN_TYPE == GL_FLOAT
-
-#if defined(INTERP_RGB)
-#undef INTERP_RGB
-#undef INTERP_ALPHA
-#define INTERP_FLOAT_RGBA
+#define ColorTemp GLfloat
+#else
+#define ColorTemp GLint  /* same as GLfixed */
 #endif
 
-#if defined(INTERP_SPEC)
-#undef INTERP_SPEC
-#define INTERP_FLOAT_SPEC
+
+/*
+ * Walk triangle edges with GLfixed or GLdouble
+ */
+#if TRIANGLE_WALK_DOUBLE
+#define GLinterp        GLdouble
+#define InterpToInt(X)  ((GLint) (X))
+#define INTERP_ONE      1.0
+#else
+#define GLinterp        GLfixed
+#define InterpToInt(X)  FixedToInt(X)
+#define INTERP_ONE      FIXED_ONE
 #endif
 
-#endif /* CHAN_TYPE == GL_FLOAT */
 
+/*
+ * Either loop over all texture units, or just use unit zero.
+ */
+#ifdef INTERP_MULTITEX
+#define TEX_UNIT_LOOP(CODE)                                    \
+   {                                                           \
+      GLuint u;                                                        \
+      for (u = 0; u < ctx->Const.MaxTextureUnits; u++) {       \
+         if (ctx->Texture._EnabledCoordUnits & (1 << u)) {     \
+            CODE                                               \
+         }                                                     \
+      }                                                                \
+   }
+#define INTERP_TEX
+#elif defined(INTERP_TEX)
+#define TEX_UNIT_LOOP(CODE)                                    \
+   {                                                           \
+      const GLuint u = 0;                                      \
+      CODE                                                     \
+   }
+#endif
 
 
 static void NAME(GLcontext *ctx, const SWvertex *v0,
@@ -97,15 +146,26 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
                                  const SWvertex *v2 )
 {
    typedef struct {
-        const SWvertex *v0, *v1;   /* Y(v0) < Y(v1) */
-        GLfloat dx;    /* X(v1) - X(v0) */
-        GLfloat dy;    /* Y(v1) - Y(v0) */
-        GLfixed fdxdy; /* dx/dy in fixed-point */
-        GLfixed fsx;   /* first sample point x coord */
-        GLfixed fsy;
-        GLfloat adjy;  /* adjust from v[0]->fy to fsy, scaled */
-        GLint lines;   /* number of lines to be sampled on this edge */
-        GLfixed fx0;   /* fixed pt X of lower endpoint */
+      const SWvertex *v0, *v1;   /* Y(v0) < Y(v1) */
+#if TRIANGLE_WALK_DOUBLE
+      GLdouble dx;     /* X(v1) - X(v0) */
+      GLdouble dy;     /* Y(v1) - Y(v0) */
+      GLdouble dxdy;   /* dx/dy */
+      GLdouble adjy;   /* adjust from v[0]->fy to fsy, scaled */
+      GLdouble fsx;    /* first sample point x coord */
+      GLdouble fsy;
+      GLdouble fx0;    /*X of lower endpoint */
+#else
+      GLfloat dx;      /* X(v1) - X(v0) */
+      GLfloat dy;      /* Y(v1) - Y(v0) */
+      GLfloat dxdy;    /* dx/dy */
+      GLfixed fdxdy;   /* dx/dy in fixed-point */
+      GLfloat adjy;    /* adjust from v[0]->fy to fsy, scaled */
+      GLfixed fsx;     /* first sample point x coord */
+      GLfixed fsy;
+      GLfixed fx0;     /* fixed pt X of lower endpoint */
+#endif
+      GLint lines;     /* number of lines to be sampled on this edge */
    } EdgeT;
 
 #ifdef INTERP_Z
@@ -117,9 +177,11 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
    EdgeT eMaj, eTop, eBot;
    GLfloat oneOverArea;
    const SWvertex *vMin, *vMid, *vMax;  /* Y(vMin)<=Y(vMid)<=Y(vMax) */
-   float bf = SWRAST_CONTEXT(ctx)->_backface_sign;
+   GLfloat bf = SWRAST_CONTEXT(ctx)->_BackfaceSign;
+#if !TRIANGLE_WALK_DOUBLE
    const GLint snapMask = ~((FIXED_ONE / (1 << SUB_PIXEL_BITS)) - 1); /* for x/y coord snapping */
-   GLfixed vMin_fx, vMin_fy, vMid_fx, vMid_fy, vMax_fx, vMax_fy;
+#endif
+   GLinterp vMin_fx, vMin_fy, vMid_fx, vMid_fy, vMax_fx, vMax_fy;
 
    struct sw_span span;
 
@@ -135,15 +197,24 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
    printf("  %g, %g, %g\n", v1->win[0], v1->win[1], v1->win[2]);
    printf("  %g, %g, %g\n", v2->win[0], v2->win[1], v2->win[2]);
    */
-
+   /*
+   ASSERT(v0->win[2] >= 0.0);
+   ASSERT(v1->win[2] >= 0.0);
+   ASSERT(v2->win[2] >= 0.0);
+   */
    /* Compute fixed point x,y coords w/ half-pixel offsets and snapping.
     * And find the order of the 3 vertices along the Y axis.
     */
    {
+#if TRIANGLE_WALK_DOUBLE
+      const GLdouble fy0 = v0->win[1] - 0.5;
+      const GLdouble fy1 = v1->win[1] - 0.5;
+      const GLdouble fy2 = v2->win[1] - 0.5;
+#else
       const GLfixed fy0 = FloatToFixed(v0->win[1] - 0.5F) & snapMask;
       const GLfixed fy1 = FloatToFixed(v1->win[1] - 0.5F) & snapMask;
       const GLfixed fy2 = FloatToFixed(v2->win[1] - 0.5F) & snapMask;
-
+#endif
       if (fy0 <= fy1) {
          if (fy1 <= fy2) {
             /* y0 <= y1 <= y2 */
@@ -183,9 +254,15 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
       }
 
       /* fixed point X coords */
+#if TRIANGLE_WALK_DOUBLE
+      vMin_fx = vMin->win[0] + 0.5;
+      vMid_fx = vMid->win[0] + 0.5;
+      vMax_fx = vMax->win[0] + 0.5;
+#else
       vMin_fx = FloatToFixed(vMin->win[0] + 0.5F) & snapMask;
       vMid_fx = FloatToFixed(vMid->win[0] + 0.5F) & snapMask;
       vMax_fx = FloatToFixed(vMax->win[0] + 0.5F) & snapMask;
+#endif
    }
 
    /* vertex/edge relationship */
@@ -194,17 +271,29 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
    eBot.v0 = vMin;   eBot.v1 = vMid;
 
    /* compute deltas for each edge:  vertex[upper] - vertex[lower] */
+#if TRIANGLE_WALK_DOUBLE
+   eMaj.dx = vMax_fx - vMin_fx;
+   eMaj.dy = vMax_fy - vMin_fy;
+   eTop.dx = vMax_fx - vMid_fx;
+   eTop.dy = vMax_fy - vMid_fy;
+   eBot.dx = vMid_fx - vMin_fx;
+   eBot.dy = vMid_fy - vMin_fy;
+#else
    eMaj.dx = FixedToFloat(vMax_fx - vMin_fx);
    eMaj.dy = FixedToFloat(vMax_fy - vMin_fy);
    eTop.dx = FixedToFloat(vMax_fx - vMid_fx);
    eTop.dy = FixedToFloat(vMax_fy - vMid_fy);
    eBot.dx = FixedToFloat(vMid_fx - vMin_fx);
    eBot.dy = FixedToFloat(vMid_fy - vMin_fy);
+#endif
 
    /* compute area, oneOverArea and perform backface culling */
    {
+#if TRIANGLE_WALK_DOUBLE
+      const GLdouble area = eMaj.dx * eBot.dy - eBot.dx * eMaj.dy;
+#else
       const GLfloat area = eMaj.dx * eBot.dy - eBot.dx * eMaj.dy;
-
+#endif
       /* Do backface culling */
       if (area * bf < 0.0)
          return;
@@ -215,44 +304,74 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
       oneOverArea = 1.0F / area;
    }
 
-#ifndef DO_OCCLUSION_TEST
-   ctx->OcclusionResult = GL_TRUE;
-#endif
    span.facing = ctx->_Facing; /* for 2-sided stencil test */
 
    /* Edge setup.  For a triangle strip these could be reused... */
    {
+#if TRIANGLE_WALK_DOUBLE
+      eMaj.fsy = CEILF(vMin_fy);
+      eMaj.lines = (GLint) CEILF(vMax_fy - eMaj.fsy);
+#else
       eMaj.fsy = FixedCeil(vMin_fy);
       eMaj.lines = FixedToInt(FixedCeil(vMax_fy - eMaj.fsy));
+#endif
       if (eMaj.lines > 0) {
-         GLfloat dxdy = eMaj.dx / eMaj.dy;
-         eMaj.fdxdy = SignedFloatToFixed(dxdy);
+         eMaj.dxdy = eMaj.dx / eMaj.dy;
+#if TRIANGLE_WALK_DOUBLE
+         eMaj.adjy = (eMaj.fsy - vMin_fy) * FIXED_SCALE;  /* SCALED! */
+         eMaj.fx0 = vMin_fx;
+         eMaj.fsx = eMaj.fx0 + (eMaj.adjy * eMaj.dxdy) / (GLdouble) FIXED_SCALE;
+#else
+         eMaj.fdxdy = SignedFloatToFixed(eMaj.dxdy);
          eMaj.adjy = (GLfloat) (eMaj.fsy - vMin_fy);  /* SCALED! */
          eMaj.fx0 = vMin_fx;
-         eMaj.fsx = eMaj.fx0 + (GLfixed) (eMaj.adjy * dxdy);
+         eMaj.fsx = eMaj.fx0 + (GLfixed) (eMaj.adjy * eMaj.dxdy);
+#endif
       }
       else {
          return;  /*CULLED*/
       }
 
+#if TRIANGLE_WALK_DOUBLE
+      eTop.fsy = CEILF(vMid_fy);
+      eTop.lines = (GLint) CEILF(vMax_fy - eTop.fsy);
+#else
       eTop.fsy = FixedCeil(vMid_fy);
       eTop.lines = FixedToInt(FixedCeil(vMax_fy - eTop.fsy));
+#endif
       if (eTop.lines > 0) {
-         GLfloat dxdy = eTop.dx / eTop.dy;
-         eTop.fdxdy = SignedFloatToFixed(dxdy);
+         eTop.dxdy = eTop.dx / eTop.dy;
+#if TRIANGLE_WALK_DOUBLE
+         eTop.adjy = (eTop.fsy - vMid_fy) * FIXED_SCALE; /* SCALED! */
+         eTop.fx0 = vMid_fx;
+         eTop.fsx = eTop.fx0 + (eTop.adjy * eTop.dxdy) / (GLdouble) FIXED_SCALE;
+#else
+         eTop.fdxdy = SignedFloatToFixed(eTop.dxdy);
          eTop.adjy = (GLfloat) (eTop.fsy - vMid_fy); /* SCALED! */
          eTop.fx0 = vMid_fx;
-         eTop.fsx = eTop.fx0 + (GLfixed) (eTop.adjy * dxdy);
+         eTop.fsx = eTop.fx0 + (GLfixed) (eTop.adjy * eTop.dxdy);
+#endif
       }
 
+#if TRIANGLE_WALK_DOUBLE
+      eBot.fsy = CEILF(vMin_fy);
+      eBot.lines = (GLint) CEILF(vMid_fy - eBot.fsy);
+#else
       eBot.fsy = FixedCeil(vMin_fy);
       eBot.lines = FixedToInt(FixedCeil(vMid_fy - eBot.fsy));
+#endif
       if (eBot.lines > 0) {
-         GLfloat dxdy = eBot.dx / eBot.dy;
-         eBot.fdxdy = SignedFloatToFixed(dxdy);
+         eBot.dxdy = eBot.dx / eBot.dy;
+#if TRIANGLE_WALK_DOUBLE
+         eBot.adjy = (eBot.fsy - vMin_fy) * FIXED_SCALE;  /* SCALED! */
+         eBot.fx0 = vMin_fx;
+         eBot.fsx = eBot.fx0 + (eBot.adjy * eBot.dxdy) / (GLdouble) FIXED_SCALE;
+#else
+         eBot.fdxdy = SignedFloatToFixed(eBot.dxdy);
          eBot.adjy = (GLfloat) (eBot.fsy - vMin_fy);  /* SCALED! */
          eBot.fx0 = vMin_fx;
-         eBot.fsx = eBot.fx0 + (GLfixed) (eBot.adjy * dxdy);
+         eBot.fsx = eBot.fx0 + (GLfixed) (eBot.adjy * eBot.dxdy);
+#endif
       }
    }
 
@@ -292,44 +411,9 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 
    {
       GLint scan_from_left_to_right;  /* true if scanning left-to-right */
-#ifdef INTERP_Z
-      GLfloat dzdx, dzdy;
-#endif
-#ifdef INTERP_FOG
-      GLfloat dfogdy;
-#endif
-#if defined(INTERP_RGB) || defined(INTERP_FLOAT_RGBA)
-      GLfloat drdx, drdy;
-      GLfloat dgdx, dgdy;
-      GLfloat dbdx, dbdy;
-#endif
-#if defined(INTERP_ALPHA) || defined(INTERP_FLOAT_RGBA)
-      GLfloat dadx, dady;
-#endif
-#if defined(INTERP_SPEC) || defined(INTERP_FLOAT_SPEC)
-      GLfloat dsrdx, dsrdy;
-      GLfloat dsgdx, dsgdy;
-      GLfloat dsbdx, dsbdy;
-#endif
 #ifdef INTERP_INDEX
       GLfloat didx, didy;
 #endif
-#ifdef INTERP_INT_TEX
-      GLfloat dsdx, dsdy;
-      GLfloat dtdx, dtdy;
-#endif
-#ifdef INTERP_TEX
-      GLfloat dsdx, dsdy;
-      GLfloat dtdx, dtdy;
-      GLfloat dudx, dudy;
-      GLfloat dvdx, dvdy;
-#endif
-#ifdef INTERP_MULTITEX
-      GLfloat dsdx[MAX_TEXTURE_COORD_UNITS], dsdy[MAX_TEXTURE_COORD_UNITS];
-      GLfloat dtdx[MAX_TEXTURE_COORD_UNITS], dtdy[MAX_TEXTURE_COORD_UNITS];
-      GLfloat dudx[MAX_TEXTURE_COORD_UNITS], dudy[MAX_TEXTURE_COORD_UNITS];
-      GLfloat dvdx[MAX_TEXTURE_COORD_UNITS], dvdy[MAX_TEXTURE_COORD_UNITS];
-#endif
 
       /*
        * Execute user-supplied setup code
@@ -345,197 +429,159 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #ifdef INTERP_Z
       span.interpMask |= SPAN_Z;
       {
-         GLfloat eMaj_dz, eBot_dz;
-         eMaj_dz = vMax->win[2] - vMin->win[2];
-         eBot_dz = vMid->win[2] - vMin->win[2];
-         dzdx = oneOverArea * (eMaj_dz * eBot.dy - eMaj.dy * eBot_dz);
-         if (dzdx > maxDepth || dzdx < -maxDepth) {
+         GLfloat eMaj_dz = vMax->win[2] - vMin->win[2];
+         GLfloat eBot_dz = vMid->win[2] - vMin->win[2];
+         span.dzdx = oneOverArea * (eMaj_dz * eBot.dy - eMaj.dy * eBot_dz);
+         if (span.dzdx > maxDepth || span.dzdx < -maxDepth) {
             /* probably a sliver triangle */
-            dzdx = 0.0;
-            dzdy = 0.0;
+            span.dzdx = 0.0;
+            span.dzdy = 0.0;
          }
          else {
-            dzdy = oneOverArea * (eMaj.dx * eBot_dz - eMaj_dz * eBot.dx);
+            span.dzdy = oneOverArea * (eMaj.dx * eBot_dz - eMaj_dz * eBot.dx);
          }
          if (depthBits <= 16)
-            span.zStep = SignedFloatToFixed(dzdx);
+            span.zStep = SignedFloatToFixed(span.dzdx);
          else
-            span.zStep = (GLint) dzdx;
+            span.zStep = (GLint) span.dzdx;
+      }
+#endif
+#ifdef INTERP_W
+      span.interpMask |= SPAN_W;
+      {
+         const GLfloat eMaj_dw = vMax->win[3] - vMin->win[3];
+         const GLfloat eBot_dw = vMid->win[3] - vMin->win[3];
+         span.dwdx = oneOverArea * (eMaj_dw * eBot.dy - eMaj.dy * eBot_dw);
+         span.dwdy = oneOverArea * (eMaj.dx * eBot_dw - eMaj_dw * eBot.dx);
       }
 #endif
 #ifdef INTERP_FOG
       span.interpMask |= SPAN_FOG;
       {
+#  ifdef INTERP_W
+         const GLfloat wMax = vMax->win[3], wMin = vMin->win[3], wMid = vMid->win[3];
+         const GLfloat eMaj_dfog = vMax->fog * wMax - vMin->fog * wMin;
+         const GLfloat eBot_dfog = vMid->fog * wMid - vMin->fog * wMin;
+#  else
          const GLfloat eMaj_dfog = vMax->fog - vMin->fog;
          const GLfloat eBot_dfog = vMid->fog - vMin->fog;
-         span.fogStep = oneOverArea * (eMaj_dfog * eBot.dy - eMaj.dy * eBot_dfog);
-         dfogdy = oneOverArea * (eMaj.dx * eBot_dfog - eMaj_dfog * eBot.dx);
+#  endif
+         span.dfogdx = oneOverArea * (eMaj_dfog * eBot.dy - eMaj.dy * eBot_dfog);
+         span.dfogdy = oneOverArea * (eMaj.dx * eBot_dfog - eMaj_dfog * eBot.dx);
+         span.fogStep = span.dfogdx;
       }
 #endif
 #ifdef INTERP_RGB
       span.interpMask |= SPAN_RGBA;
       if (ctx->Light.ShadeModel == GL_SMOOTH) {
-         GLfloat eMaj_dr, eBot_dr;
-         GLfloat eMaj_dg, eBot_dg;
-         GLfloat eMaj_db, eBot_db;
+         GLfloat eMaj_dr = (GLfloat) ((ColorTemp) vMax->color[RCOMP] - (ColorTemp) vMin->color[RCOMP]);
+         GLfloat eBot_dr = (GLfloat) ((ColorTemp) vMid->color[RCOMP] - (ColorTemp) vMin->color[RCOMP]);
+         GLfloat eMaj_dg = (GLfloat) ((ColorTemp) vMax->color[GCOMP] - (ColorTemp) vMin->color[GCOMP]);
+         GLfloat eBot_dg = (GLfloat) ((ColorTemp) vMid->color[GCOMP] - (ColorTemp) vMin->color[GCOMP]);
+         GLfloat eMaj_db = (GLfloat) ((ColorTemp) vMax->color[BCOMP] - (ColorTemp) vMin->color[BCOMP]);
+         GLfloat eBot_db = (GLfloat) ((ColorTemp) vMid->color[BCOMP] - (ColorTemp) vMin->color[BCOMP]);
 #  ifdef INTERP_ALPHA
-         GLfloat eMaj_da, eBot_da;
+         GLfloat eMaj_da = (GLfloat) ((ColorTemp) vMax->color[ACOMP] - (ColorTemp) vMin->color[ACOMP]);
+         GLfloat eBot_da = (GLfloat) ((ColorTemp) vMid->color[ACOMP] - (ColorTemp) vMin->color[ACOMP]);
 #  endif
-         eMaj_dr = (GLfloat) ((GLint) vMax->color[RCOMP] - 
-                             (GLint) vMin->color[RCOMP]);
-         eBot_dr = (GLfloat) ((GLint) vMid->color[RCOMP] - 
-                             (GLint) vMin->color[RCOMP]);
-         drdx = oneOverArea * (eMaj_dr * eBot.dy - eMaj.dy * eBot_dr);
-         span.redStep = SignedFloatToFixed(drdx);
-         drdy = oneOverArea * (eMaj.dx * eBot_dr - eMaj_dr * eBot.dx);
-         eMaj_dg = (GLfloat) ((GLint) vMax->color[GCOMP] - 
-                             (GLint) vMin->color[GCOMP]);
-         eBot_dg = (GLfloat) ((GLint) vMid->color[GCOMP] - 
-                             (GLint) vMin->color[GCOMP]);
-         dgdx = oneOverArea * (eMaj_dg * eBot.dy - eMaj.dy * eBot_dg);
-         span.greenStep = SignedFloatToFixed(dgdx);
-         dgdy = oneOverArea * (eMaj.dx * eBot_dg - eMaj_dg * eBot.dx);
-         eMaj_db = (GLfloat) ((GLint) vMax->color[BCOMP] - 
-                             (GLint) vMin->color[BCOMP]);
-         eBot_db = (GLfloat) ((GLint) vMid->color[BCOMP] - 
-                             (GLint) vMin->color[BCOMP]);
-         dbdx = oneOverArea * (eMaj_db * eBot.dy - eMaj.dy * eBot_db);
-         span.blueStep = SignedFloatToFixed(dbdx);
-         dbdy = oneOverArea * (eMaj.dx * eBot_db - eMaj_db * eBot.dx);
+         span.drdx = oneOverArea * (eMaj_dr * eBot.dy - eMaj.dy * eBot_dr);
+         span.drdy = oneOverArea * (eMaj.dx * eBot_dr - eMaj_dr * eBot.dx);
+         span.dgdx = oneOverArea * (eMaj_dg * eBot.dy - eMaj.dy * eBot_dg);
+         span.dgdy = oneOverArea * (eMaj.dx * eBot_dg - eMaj_dg * eBot.dx);
+         span.dbdx = oneOverArea * (eMaj_db * eBot.dy - eMaj.dy * eBot_db);
+         span.dbdy = oneOverArea * (eMaj.dx * eBot_db - eMaj_db * eBot.dx);
+#  if CHAN_TYPE == GL_FLOAT
+         span.redStep   = span.drdx;
+         span.greenStep = span.dgdx;
+         span.blueStep  = span.dbdx;
+#  else
+         span.redStep   = SignedFloatToFixed(span.drdx);
+         span.greenStep = SignedFloatToFixed(span.dgdx);
+         span.blueStep  = SignedFloatToFixed(span.dbdx);
+#  endif /* GL_FLOAT */
 #  ifdef INTERP_ALPHA
-         eMaj_da = (GLfloat) ((GLint) vMax->color[ACOMP] - 
-                             (GLint) vMin->color[ACOMP]);
-         eBot_da = (GLfloat) ((GLint) vMid->color[ACOMP] - 
-                             (GLint) vMin->color[ACOMP]);
-         dadx = oneOverArea * (eMaj_da * eBot.dy - eMaj.dy * eBot_da);
-         span.alphaStep = SignedFloatToFixed(dadx);
-         dady = oneOverArea * (eMaj.dx * eBot_da - eMaj_da * eBot.dx);
-#  endif
+         span.dadx = oneOverArea * (eMaj_da * eBot.dy - eMaj.dy * eBot_da);
+         span.dady = oneOverArea * (eMaj.dx * eBot_da - eMaj_da * eBot.dx);
+#    if CHAN_TYPE == GL_FLOAT
+         span.alphaStep = span.dadx;
+#    else
+         span.alphaStep = SignedFloatToFixed(span.dadx);
+#    endif /* GL_FLOAT */
+#  endif /* INTERP_ALPHA */
       }
       else {
          ASSERT (ctx->Light.ShadeModel == GL_FLAT);
          span.interpMask |= SPAN_FLAT;
-         drdx = drdy = 0.0F;
-         dgdx = dgdy = 0.0F;
-         dbdx = dbdy = 0.0F;
-         span.redStep = 0;
-         span.greenStep = 0;
-         span.blueStep = 0;
+         span.drdx = span.drdy = 0.0F;
+         span.dgdx = span.dgdy = 0.0F;
+         span.dbdx = span.dbdy = 0.0F;
+#    if CHAN_TYPE == GL_FLOAT
+        span.redStep   = 0.0F;
+        span.greenStep = 0.0F;
+        span.blueStep  = 0.0F;
+#    else
+        span.redStep   = 0;
+        span.greenStep = 0;
+        span.blueStep  = 0;
+#    endif /* GL_FLOAT */
 #  ifdef INTERP_ALPHA
-         dadx = dady = 0.0F;
-         span.alphaStep = 0;
+         span.dadx = span.dady = 0.0F;
+#    if CHAN_TYPE == GL_FLOAT
+        span.alphaStep = 0.0F;
+#    else
+        span.alphaStep = 0;
+#    endif /* GL_FLOAT */
 #  endif
       }
-#endif
-#ifdef INTERP_FLOAT_RGBA
-      span.interpMask |= SPAN_RGBA;
-      if (ctx->Light.ShadeModel == GL_SMOOTH) {
-         GLfloat eMaj_dr, eBot_dr;
-         GLfloat eMaj_dg, eBot_dg;
-         GLfloat eMaj_db, eBot_db;
-         GLfloat eMaj_da, eBot_da;
-         eMaj_dr = vMax->color[RCOMP] - vMin->color[RCOMP];
-         eBot_dr = vMid->color[RCOMP] - vMin->color[RCOMP];
-         drdx = oneOverArea * (eMaj_dr * eBot.dy - eMaj.dy * eBot_dr);
-         span.redStep = drdx;
-         drdy = oneOverArea * (eMaj.dx * eBot_dr - eMaj_dr * eBot.dx);
-         eMaj_dg = vMax->color[GCOMP] - vMin->color[GCOMP];
-         eBot_dg = vMid->color[GCOMP] - vMin->color[GCOMP];
-         dgdx = oneOverArea * (eMaj_dg * eBot.dy - eMaj.dy * eBot_dg);
-         span.greenStep = dgdx;
-         dgdy = oneOverArea * (eMaj.dx * eBot_dg - eMaj_dg * eBot.dx);
-         eMaj_db = vMax->color[BCOMP] - vMin->color[BCOMP];
-         eBot_db = vMid->color[BCOMP] - vMin->color[BCOMP];
-         dbdx = oneOverArea * (eMaj_db * eBot.dy - eMaj.dy * eBot_db);
-         span.blueStep = dbdx;
-         dbdy = oneOverArea * (eMaj.dx * eBot_db - eMaj_db * eBot.dx);
-         eMaj_da = vMax->color[ACOMP] - vMin->color[ACOMP];
-         eBot_da = vMid->color[ACOMP] - vMin->color[ACOMP];
-         dadx = oneOverArea * (eMaj_da * eBot.dy - eMaj.dy * eBot_da);
-         span.alphaStep = dadx;
-         dady = oneOverArea * (eMaj.dx * eBot_da - eMaj_da * eBot.dx);
-      }
-      else {
-         drdx = drdy = span.redStep = 0.0F;
-         dgdx = dgdy = span.greenStep = 0.0F;
-         dbdx = dbdy = span.blueStep = 0.0F;
-         dadx = dady = span.alphaStep = 0.0F;
-      }
-#endif
+#endif /* INTERP_RGB */
 #ifdef INTERP_SPEC
       span.interpMask |= SPAN_SPEC;
       if (ctx->Light.ShadeModel == GL_SMOOTH) {
-         GLfloat eMaj_dsr, eBot_dsr;
-         GLfloat eMaj_dsg, eBot_dsg;
-         GLfloat eMaj_dsb, eBot_dsb;
-         eMaj_dsr = (GLfloat) ((GLint) vMax->specular[RCOMP] - 
-                              (GLint) vMin->specular[RCOMP]);
-         eBot_dsr = (GLfloat) ((GLint) vMid->specular[RCOMP] - 
-                              (GLint) vMin->specular[RCOMP]);
-         dsrdx = oneOverArea * (eMaj_dsr * eBot.dy - eMaj.dy * eBot_dsr);
-         span.specRedStep = SignedFloatToFixed(dsrdx);
-         dsrdy = oneOverArea * (eMaj.dx * eBot_dsr - eMaj_dsr * eBot.dx);
-         eMaj_dsg = (GLfloat) ((GLint) vMax->specular[GCOMP] - 
-                              (GLint) vMin->specular[GCOMP]);
-         eBot_dsg = (GLfloat) ((GLint) vMid->specular[GCOMP] - 
-                              (GLint) vMin->specular[GCOMP]);
-         dsgdx = oneOverArea * (eMaj_dsg * eBot.dy - eMaj.dy * eBot_dsg);
-         span.specGreenStep = SignedFloatToFixed(dsgdx);
-         dsgdy = oneOverArea * (eMaj.dx * eBot_dsg - eMaj_dsg * eBot.dx);
-         eMaj_dsb = (GLfloat) ((GLint) vMax->specular[BCOMP] - 
-                              (GLint) vMin->specular[BCOMP]);
-         eBot_dsb = (GLfloat) ((GLint) vMid->specular[BCOMP] - 
-                              (GLint) vMin->specular[BCOMP]);
-         dsbdx = oneOverArea * (eMaj_dsb * eBot.dy - eMaj.dy * eBot_dsb);
-         span.specBlueStep = SignedFloatToFixed(dsbdx);
-         dsbdy = oneOverArea * (eMaj.dx * eBot_dsb - eMaj_dsb * eBot.dx);
-      }
-      else {
-         dsrdx = dsrdy = 0.0F;
-         dsgdx = dsgdy = 0.0F;
-         dsbdx = dsbdy = 0.0F;
-         span.specRedStep = 0;
-         span.specGreenStep = 0;
-         span.specBlueStep = 0;
-      }
-#endif
-#ifdef INTERP_FLOAT_SPEC
-      span.interpMask |= SPAN_SPEC;
-      if (ctx->Light.ShadeModel == GL_SMOOTH) {
-         GLfloat eMaj_dsr, eBot_dsr;
-         GLfloat eMaj_dsg, eBot_dsg;
-         GLfloat eMaj_dsb, eBot_dsb;
-         eMaj_dsr = vMax->specular[RCOMP] - vMin->specular[RCOMP];
-         eBot_dsr = vMid->specular[RCOMP] - vMin->specular[RCOMP];
-         dsrdx = oneOverArea * (eMaj_dsr * eBot.dy - eMaj.dy * eBot_dsr);
-         span.specRedStep = dsrdx;
-         dsrdy = oneOverArea * (eMaj.dx * eBot_dsr - eMaj_dsr * eBot.dx);
-         eMaj_dsg = vMax->specular[GCOMP] - vMin->specular[GCOMP];
-         eBot_dsg = vMid->specular[GCOMP] - vMin->specular[GCOMP];
-         dsgdx = oneOverArea * (eMaj_dsg * eBot.dy - eMaj.dy * eBot_dsg);
-         span.specGreenStep = dsgdx;
-         dsgdy = oneOverArea * (eMaj.dx * eBot_dsg - eMaj_dsg * eBot.dx);
-         eMaj_dsb = vMax->specular[BCOMP] - vMin->specular[BCOMP];
-         eBot_dsb = vMid->specular[BCOMP] - vMin->specular[BCOMP];
-         dsbdx = oneOverArea * (eMaj_dsb * eBot.dy - eMaj.dy * eBot_dsb);
-         span.specBlueStep = dsbdx;
-         dsbdy = oneOverArea * (eMaj.dx * eBot_dsb - eMaj_dsb * eBot.dx);
+         GLfloat eMaj_dsr = (GLfloat) ((ColorTemp) vMax->specular[RCOMP] - (ColorTemp) vMin->specular[RCOMP]);
+         GLfloat eBot_dsr = (GLfloat) ((ColorTemp) vMid->specular[RCOMP] - (ColorTemp) vMin->specular[RCOMP]);
+         GLfloat eMaj_dsg = (GLfloat) ((ColorTemp) vMax->specular[GCOMP] - (ColorTemp) vMin->specular[GCOMP]);
+         GLfloat eBot_dsg = (GLfloat) ((ColorTemp) vMid->specular[GCOMP] - (ColorTemp) vMin->specular[GCOMP]);
+         GLfloat eMaj_dsb = (GLfloat) ((ColorTemp) vMax->specular[BCOMP] - (ColorTemp) vMin->specular[BCOMP]);
+         GLfloat eBot_dsb = (GLfloat) ((ColorTemp) vMid->specular[BCOMP] - (ColorTemp) vMin->specular[BCOMP]);
+         span.dsrdx = oneOverArea * (eMaj_dsr * eBot.dy - eMaj.dy * eBot_dsr);
+         span.dsrdy = oneOverArea * (eMaj.dx * eBot_dsr - eMaj_dsr * eBot.dx);
+         span.dsgdx = oneOverArea * (eMaj_dsg * eBot.dy - eMaj.dy * eBot_dsg);
+         span.dsgdy = oneOverArea * (eMaj.dx * eBot_dsg - eMaj_dsg * eBot.dx);
+         span.dsbdx = oneOverArea * (eMaj_dsb * eBot.dy - eMaj.dy * eBot_dsb);
+         span.dsbdy = oneOverArea * (eMaj.dx * eBot_dsb - eMaj_dsb * eBot.dx);
+#  if CHAN_TYPE == GL_FLOAT
+         span.specRedStep   = span.dsrdx;
+         span.specGreenStep = span.dsgdx;
+         span.specBlueStep  = span.dsbdx;
+#  else
+         span.specRedStep   = SignedFloatToFixed(span.dsrdx);
+         span.specGreenStep = SignedFloatToFixed(span.dsgdx);
+         span.specBlueStep  = SignedFloatToFixed(span.dsbdx);
+#  endif
       }
       else {
-         dsrdx = dsrdy = span.specRedStep = 0;
-         dsgdx = dsgdy = span.specGreenStep = 0;
-         dsbdx = dsbdy = span.specBlueStep = 0;
+         span.dsrdx = span.dsrdy = 0.0F;
+         span.dsgdx = span.dsgdy = 0.0F;
+         span.dsbdx = span.dsbdy = 0.0F;
+#  if CHAN_TYPE == GL_FLOAT
+        span.specRedStep   = 0.0F;
+        span.specGreenStep = 0.0F;
+        span.specBlueStep  = 0.0F;
+#  else
+        span.specRedStep   = 0;
+        span.specGreenStep = 0;
+        span.specBlueStep  = 0;
+#  endif
       }
-#endif
+#endif /* INTERP_SPEC */
 #ifdef INTERP_INDEX
       span.interpMask |= SPAN_INDEX;
       if (ctx->Light.ShadeModel == GL_SMOOTH) {
-         GLfloat eMaj_di, eBot_di;
-         eMaj_di = (GLfloat) ((GLint) vMax->index - (GLint) vMin->index);
-         eBot_di = (GLfloat) ((GLint) vMid->index - (GLint) vMin->index);
+         GLfloat eMaj_di = vMax->index - vMin->index;
+         GLfloat eBot_di = vMid->index - vMin->index;
          didx = oneOverArea * (eMaj_di * eBot.dy - eMaj.dy * eBot_di);
-         span.indexStep = SignedFloatToFixed(didx);
          didy = oneOverArea * (eMaj.dx * eBot_di - eMaj_di * eBot.dx);
+         span.indexStep = SignedFloatToFixed(didx);
       }
       else {
          span.interpMask |= SPAN_FLAT;
@@ -546,113 +592,41 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #ifdef INTERP_INT_TEX
       span.interpMask |= SPAN_INT_TEXTURE;
       {
-         GLfloat eMaj_ds, eBot_ds;
-         eMaj_ds = (vMax->texcoord[0][0] - vMin->texcoord[0][0]) * S_SCALE;
-         eBot_ds = (vMid->texcoord[0][0] - vMin->texcoord[0][0]) * S_SCALE;
-         dsdx = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds);
-         span.intTexStep[0] = SignedFloatToFixed(dsdx);
-         dsdy = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx);
-      }
-      {
-         GLfloat eMaj_dt, eBot_dt;
-         eMaj_dt = (vMax->texcoord[0][1] - vMin->texcoord[0][1]) * T_SCALE;
-         eBot_dt = (vMid->texcoord[0][1] - vMin->texcoord[0][1]) * T_SCALE;
-         dtdx = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt);
-         span.intTexStep[1] = SignedFloatToFixed(dtdx);
-         dtdy = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx);
+         GLfloat eMaj_ds = (vMax->texcoord[0][0] - vMin->texcoord[0][0]) * S_SCALE;
+         GLfloat eBot_ds = (vMid->texcoord[0][0] - vMin->texcoord[0][0]) * S_SCALE;
+         GLfloat eMaj_dt = (vMax->texcoord[0][1] - vMin->texcoord[0][1]) * T_SCALE;
+         GLfloat eBot_dt = (vMid->texcoord[0][1] - vMin->texcoord[0][1]) * T_SCALE;
+         span.texStepX[0][0] = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds);
+         span.texStepY[0][0] = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx);
+         span.texStepX[0][1] = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt);
+         span.texStepY[0][1] = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx);
+         span.intTexStep[0] = SignedFloatToFixed(span.texStepX[0][0]);
+         span.intTexStep[1] = SignedFloatToFixed(span.texStepX[0][1]);
       }
-
 #endif
 #ifdef INTERP_TEX
       span.interpMask |= SPAN_TEXTURE;
       {
-         GLfloat wMax = vMax->win[3];
-         GLfloat wMin = vMin->win[3];
-         GLfloat wMid = vMid->win[3];
-         GLfloat eMaj_ds, eBot_ds;
-         GLfloat eMaj_dt, eBot_dt;
-         GLfloat eMaj_du, eBot_du;
-         GLfloat eMaj_dv, eBot_dv;
-
-         eMaj_ds = vMax->texcoord[0][0] * wMax - vMin->texcoord[0][0] * wMin;
-         eBot_ds = vMid->texcoord[0][0] * wMid - vMin->texcoord[0][0] * wMin;
-         dsdx = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds);
-         dsdy = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx);
-         span.texStepX[0][0] = dsdx;
-         span.texStepY[0][0] = dsdy;
-
-         eMaj_dt = vMax->texcoord[0][1] * wMax - vMin->texcoord[0][1] * wMin;
-         eBot_dt = vMid->texcoord[0][1] * wMid - vMin->texcoord[0][1] * wMin;
-         dtdx = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt);
-         dtdy = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx);
-         span.texStepX[0][1] = dtdx;
-         span.texStepY[0][1] = dtdy;
-
-         eMaj_du = vMax->texcoord[0][2] * wMax - vMin->texcoord[0][2] * wMin;
-         eBot_du = vMid->texcoord[0][2] * wMid - vMin->texcoord[0][2] * wMin;
-         dudx = oneOverArea * (eMaj_du * eBot.dy - eMaj.dy * eBot_du);
-         dudy = oneOverArea * (eMaj.dx * eBot_du - eMaj_du * eBot.dx);
-         span.texStepX[0][2] = dudx;
-         span.texStepY[0][2] = dudy;
-
-         eMaj_dv = vMax->texcoord[0][3] * wMax - vMin->texcoord[0][3] * wMin;
-         eBot_dv = vMid->texcoord[0][3] * wMid - vMin->texcoord[0][3] * wMin;
-         dvdx = oneOverArea * (eMaj_dv * eBot.dy - eMaj.dy * eBot_dv);
-         dvdy = oneOverArea * (eMaj.dx * eBot_dv - eMaj_dv * eBot.dx);
-         span.texStepX[0][3] = dvdx;
-         span.texStepY[0][3] = dvdy;
-      }
-#endif
-#ifdef INTERP_MULTITEX
-      span.interpMask |= SPAN_TEXTURE;
-      {
-         GLfloat wMax = vMax->win[3];
-         GLfloat wMin = vMin->win[3];
-         GLfloat wMid = vMid->win[3];
-         GLuint u;
-         for (u = 0; u < ctx->Const.MaxTextureUnits; u++) {
-            if (ctx->Texture.Unit[u]._ReallyEnabled) {
-               GLfloat eMaj_ds, eBot_ds;
-               GLfloat eMaj_dt, eBot_dt;
-               GLfloat eMaj_du, eBot_du;
-               GLfloat eMaj_dv, eBot_dv;
-               eMaj_ds = vMax->texcoord[u][0] * wMax
-                       - vMin->texcoord[u][0] * wMin;
-               eBot_ds = vMid->texcoord[u][0] * wMid
-                       - vMin->texcoord[u][0] * wMin;
-               dsdx[u] = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds);
-               dsdy[u] = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx);
-               span.texStepX[u][0] = dsdx[u];
-               span.texStepY[u][0] = dsdy[u];
-
-               eMaj_dt = vMax->texcoord[u][1] * wMax
-                       - vMin->texcoord[u][1] * wMin;
-               eBot_dt = vMid->texcoord[u][1] * wMid
-                       - vMin->texcoord[u][1] * wMin;
-               dtdx[u] = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt);
-               dtdy[u] = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx);
-               span.texStepX[u][1] = dtdx[u];
-               span.texStepY[u][1] = dtdy[u];
-
-               eMaj_du = vMax->texcoord[u][2] * wMax
-                       - vMin->texcoord[u][2] * wMin;
-               eBot_du = vMid->texcoord[u][2] * wMid
-                       - vMin->texcoord[u][2] * wMin;
-               dudx[u] = oneOverArea * (eMaj_du * eBot.dy - eMaj.dy * eBot_du);
-               dudy[u] = oneOverArea * (eMaj.dx * eBot_du - eMaj_du * eBot.dx);
-               span.texStepX[u][2] = dudx[u];
-               span.texStepY[u][2] = dudy[u];
-
-               eMaj_dv = vMax->texcoord[u][3] * wMax
-                       - vMin->texcoord[u][3] * wMin;
-               eBot_dv = vMid->texcoord[u][3] * wMid
-                       - vMin->texcoord[u][3] * wMin;
-               dvdx[u] = oneOverArea * (eMaj_dv * eBot.dy - eMaj.dy * eBot_dv);
-               dvdy[u] = oneOverArea * (eMaj.dx * eBot_dv - eMaj_dv * eBot.dx);
-               span.texStepX[u][3] = dvdx[u];
-               span.texStepY[u][3] = dvdy[u];
-            }
-         }
+         /* win[3] is 1/W */
+         const GLfloat wMax = vMax->win[3], wMin = vMin->win[3], wMid = vMid->win[3];
+         TEX_UNIT_LOOP(
+            GLfloat eMaj_ds = vMax->texcoord[u][0] * wMax - vMin->texcoord[u][0] * wMin;
+            GLfloat eBot_ds = vMid->texcoord[u][0] * wMid - vMin->texcoord[u][0] * wMin;
+            GLfloat eMaj_dt = vMax->texcoord[u][1] * wMax - vMin->texcoord[u][1] * wMin;
+            GLfloat eBot_dt = vMid->texcoord[u][1] * wMid - vMin->texcoord[u][1] * wMin;
+            GLfloat eMaj_du = vMax->texcoord[u][2] * wMax - vMin->texcoord[u][2] * wMin;
+            GLfloat eBot_du = vMid->texcoord[u][2] * wMid - vMin->texcoord[u][2] * wMin;
+            GLfloat eMaj_dv = vMax->texcoord[u][3] * wMax - vMin->texcoord[u][3] * wMin;
+            GLfloat eBot_dv = vMid->texcoord[u][3] * wMid - vMin->texcoord[u][3] * wMin;
+            span.texStepX[u][0] = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds);
+            span.texStepY[u][0] = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx);
+            span.texStepX[u][1] = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt);
+            span.texStepY[u][1] = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx);
+            span.texStepX[u][2] = oneOverArea * (eMaj_du * eBot.dy - eMaj.dy * eBot_du);
+            span.texStepY[u][2] = oneOverArea * (eMaj.dx * eBot_du - eMaj_du * eBot.dx);
+            span.texStepX[u][3] = oneOverArea * (eMaj_dv * eBot.dy - eMaj.dy * eBot_dv);
+            span.texStepY[u][3] = oneOverArea * (eMaj.dx * eBot_dv - eMaj_dv * eBot.dx);
+         )
       }
 #endif
 
@@ -704,68 +678,48 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
        */
 
       {
-         int subTriangle;
-         GLfixed fx;
-         GLfixed fxLeftEdge = 0, fxRightEdge = 0;
-         GLfixed fdxLeftEdge = 0, fdxRightEdge = 0;
-         GLfixed fdxOuter;
-         int idxOuter;
-         float dxOuter;
-         GLfixed fError = 0, fdError = 0;
-         float adjx, adjy;
-         GLfixed fy;
+         GLint subTriangle;
+         GLinterp fxLeftEdge = 0, fxRightEdge = 0;
+         GLinterp fdxLeftEdge = 0, fdxRightEdge = 0;
+         GLinterp fError = 0, fdError = 0;
 #ifdef PIXEL_ADDRESS
          PIXEL_TYPE *pRow = NULL;
-         int dPRowOuter = 0, dPRowInner;  /* offset in bytes */
+         GLint dPRowOuter = 0, dPRowInner;  /* offset in bytes */
 #endif
 #ifdef INTERP_Z
 #  ifdef DEPTH_TYPE
          DEPTH_TYPE *zRow = NULL;
-         int dZRowOuter = 0, dZRowInner;  /* offset in bytes */
+         GLint dZRowOuter = 0, dZRowInner;  /* offset in bytes */
 #  endif
-         GLfixed fz = 0, fdzOuter = 0, fdzInner;
+         GLfixed zLeft = 0, fdzOuter = 0, fdzInner;
+#endif
+#ifdef INTERP_W
+         GLfloat wLeft = 0, dwOuter = 0, dwInner;
 #endif
 #ifdef INTERP_FOG
          GLfloat fogLeft = 0, dfogOuter = 0, dfogInner;
 #endif
 #ifdef INTERP_RGB
-         GLfixed fr = 0, fdrOuter = 0, fdrInner;
-         GLfixed fg = 0, fdgOuter = 0, fdgInner;
-         GLfixed fb = 0, fdbOuter = 0, fdbInner;
+         ColorTemp rLeft = 0, fdrOuter = 0, fdrInner;
+         ColorTemp gLeft = 0, fdgOuter = 0, fdgInner;
+         ColorTemp bLeft = 0, fdbOuter = 0, fdbInner;
 #endif
 #ifdef INTERP_ALPHA
-         GLfixed fa = 0, fdaOuter = 0, fdaInner;
-#endif
-#ifdef INTERP_FLOAT_RGBA
-         GLfloat fr, fdrOuter, fdrInner;
-         GLfloat fg, fdgOuter, fdgInner;
-         GLfloat fb, fdbOuter, fdbInner;
-         GLfloat fa, fdaOuter, fdaInner;
+         ColorTemp aLeft = 0, fdaOuter = 0, fdaInner;
 #endif
 #ifdef INTERP_SPEC
-         GLfixed fsr=0, fdsrOuter=0, fdsrInner;
-         GLfixed fsg=0, fdsgOuter=0, fdsgInner;
-         GLfixed fsb=0, fdsbOuter=0, fdsbInner;
-#endif
-#ifdef INTERP_FLOAT_SPEC
-         GLfloat fsr=0, fdsrOuter=0, fdsrInner;
-         GLfloat fsg=0, fdsgOuter=0, fdsgInner;
-         GLfloat fsb=0, fdsbOuter=0, fdsbInner;
+         ColorTemp srLeft=0, dsrOuter=0, dsrInner;
+         ColorTemp sgLeft=0, dsgOuter=0, dsgInner;
+         ColorTemp sbLeft=0, dsbOuter=0, dsbInner;
 #endif
 #ifdef INTERP_INDEX
-         GLfixed fi=0, fdiOuter=0, fdiInner;
+         GLfixed iLeft=0, diOuter=0, diInner;
 #endif
 #ifdef INTERP_INT_TEX
-         GLfixed fs=0, fdsOuter=0, fdsInner;
-         GLfixed ft=0, fdtOuter=0, fdtInner;
+         GLfixed sLeft=0, dsOuter=0, dsInner;
+         GLfixed tLeft=0, dtOuter=0, dtInner;
 #endif
 #ifdef INTERP_TEX
-         GLfloat sLeft=0, dsOuter=0, dsInner;
-         GLfloat tLeft=0, dtOuter=0, dtInner;
-         GLfloat uLeft=0, duOuter=0, duInner;
-         GLfloat vLeft=0, dvOuter=0, dvInner;
-#endif
-#ifdef INTERP_MULTITEX
          GLfloat sLeft[MAX_TEXTURE_COORD_UNITS];
          GLfloat tLeft[MAX_TEXTURE_COORD_UNITS];
          GLfloat uLeft[MAX_TEXTURE_COORD_UNITS];
@@ -819,39 +773,60 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
             }
 
             if (setupLeft && eLeft->lines > 0) {
-               const SWvertex *vLower;
-               GLfixed fsx = eLeft->fsx;
-               fx = FixedCeil(fsx);
+               const SWvertex *vLower = eLeft->v0;
+#if TRIANGLE_WALK_DOUBLE
+               const GLdouble fsy = eLeft->fsy;
+               const GLdouble fsx = eLeft->fsx;
+               const GLdouble fx = CEILF(fsx);
+               const GLdouble adjx = (fx - eLeft->fx0) * FIXED_SCALE;  /* SCALED! */
+#else
+               const GLfixed fsy = eLeft->fsy;
+               const GLfixed fsx = eLeft->fsx;  /* no fractional part */
+               const GLfixed fx = FixedCeil(fsx);  /* no fractional part */
+               const GLfixed adjx = (GLinterp) (fx - eLeft->fx0); /* SCALED! */
+#endif
+               const GLinterp adjy = (GLinterp) eLeft->adjy;      /* SCALED! */
+               GLint idxOuter;
+#if TRIANGLE_WALK_DOUBLE
+               GLdouble dxOuter;
+
+               fError = fx - fsx - 1.0;
+               fxLeftEdge = fsx;
+               fdxLeftEdge = eLeft->dxdy;
+               dxOuter = FLOORF(fdxLeftEdge);
+               fdError = dxOuter - fdxLeftEdge + 1.0;
+               idxOuter = (GLint) dxOuter;
+               span.y = (GLint) fsy;
+#else
+               GLfloat dxOuter;
+               GLfixed fdxOuter;
+
                fError = fx - fsx - FIXED_ONE;
                fxLeftEdge = fsx - FIXED_EPSILON;
                fdxLeftEdge = eLeft->fdxdy;
                fdxOuter = FixedFloor(fdxLeftEdge - FIXED_EPSILON);
                fdError = fdxOuter - fdxLeftEdge + FIXED_ONE;
                idxOuter = FixedToInt(fdxOuter);
-               dxOuter = (float) idxOuter;
-               (void) dxOuter;
-
-               fy = eLeft->fsy;
-               span.y = FixedToInt(fy);
-
-               adjx = (float)(fx - eLeft->fx0);  /* SCALED! */
-               adjy = eLeft->adjy;              /* SCALED! */
-               (void) adjx;  /* silence compiler warnings */
-               (void) adjy;  /* silence compiler warnings */
+               dxOuter = (GLfloat) idxOuter;
+               span.y = FixedToInt(fsy);
+#endif
 
-               vLower = eLeft->v0;
-               (void) vLower;  /* silence compiler warnings */
+               /* silence warnings on some compilers */
+               (void) dxOuter;
+               (void) adjx;
+               (void) adjy;
+               (void) vLower;
 
 #ifdef PIXEL_ADDRESS
                {
-                  pRow = (PIXEL_TYPE *) PIXEL_ADDRESS(FixedToInt(fxLeftEdge), span.y);
+                  pRow = (PIXEL_TYPE *) PIXEL_ADDRESS(InterpToInt(fxLeftEdge), span.y);
                   dPRowOuter = -((int)BYTES_PER_ROW) + idxOuter * sizeof(PIXEL_TYPE);
                   /* negative because Y=0 at bottom and increases upward */
                }
 #endif
                /*
                 * Now we need the set of parameter (z, color, etc.) values at
-                * the point (fx, fy).  This gives us properly-sampled parameter
+                * the point (fx, fsy).  This gives us properly-sampled parameter
                 * values that we can step from pixel to pixel.  Furthermore,
                 * although we might have intermediate results that overflow
                 * the normal parameter range when we step temporarily outside
@@ -864,203 +839,175 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
                   GLfloat z0 = vLower->win[2];
                   if (depthBits <= 16) {
                      /* interpolate fixed-pt values */
-                     GLfloat tmp = (z0 * FIXED_SCALE +
-                                    dzdx * adjx + dzdy * adjy) + FIXED_HALF;
+                     GLfloat tmp = (z0 * FIXED_SCALE + span.dzdx * adjx + span.dzdy * adjy) + FIXED_HALF;
                      if (tmp < MAX_GLUINT / 2)
-                        fz = (GLfixed) tmp;
+                        zLeft = (GLfixed) tmp;
                      else
-                        fz = MAX_GLUINT / 2;
-                     fdzOuter = SignedFloatToFixed(dzdy + dxOuter * dzdx);
+                        zLeft = MAX_GLUINT / 2;
+                     fdzOuter = SignedFloatToFixed(span.dzdy + dxOuter * span.dzdx);
                   }
                   else {
                      /* interpolate depth values exactly */
-                     fz = (GLint) (z0 + dzdx * FixedToFloat(adjx)
-                                   + dzdy * FixedToFloat(adjy));
-                     fdzOuter = (GLint) (dzdy + dxOuter * dzdx);
+                     zLeft = (GLint) (z0 + span.dzdx * FixedToFloat(adjx) + span.dzdy * FixedToFloat(adjy));
+                     fdzOuter = (GLint) (span.dzdy + dxOuter * span.dzdx);
                   }
 #  ifdef DEPTH_TYPE
                   zRow = (DEPTH_TYPE *)
-                    _mesa_zbuffer_address(ctx, FixedToInt(fxLeftEdge), span.y);
+                    _swrast_zbuffer_address(ctx, InterpToInt(fxLeftEdge), span.y);
                   dZRowOuter = (ctx->DrawBuffer->Width + idxOuter) * sizeof(DEPTH_TYPE);
 #  endif
                }
 #endif
+#ifdef INTERP_W
+               wLeft = vLower->win[3] + (span.dwdx * adjx + span.dwdy * adjy) * (1.0F/FIXED_SCALE);
+               dwOuter = span.dwdy + dxOuter * span.dwdx;
+#endif
 #ifdef INTERP_FOG
-               fogLeft = vLower->fog + (span.fogStep * adjx + dfogdy * adjy)
-                                       * (1.0F/FIXED_SCALE);
-               dfogOuter = dfogdy + dxOuter * span.fogStep;
+#  ifdef INTERP_W
+               fogLeft = vLower->fog * vLower->win[3] + (span.dfogdx * adjx + span.dfogdy * adjy) * (1.0F/FIXED_SCALE);
+#  else
+               fogLeft = vLower->fog + (span.dfogdx * adjx + span.dfogdy * adjy) * (1.0F/FIXED_SCALE);
+#  endif
+               dfogOuter = span.dfogdy + dxOuter * span.dfogdx;
 #endif
 #ifdef INTERP_RGB
                if (ctx->Light.ShadeModel == GL_SMOOTH) {
-                  fr = (GLfixed) (ChanToFixed(vLower->color[RCOMP])
-                                   + drdx * adjx + drdy * adjy) + FIXED_HALF;
-                  fdrOuter = SignedFloatToFixed(drdy + dxOuter * drdx);
-                  fg = (GLfixed) (ChanToFixed(vLower->color[GCOMP])
-                                   + dgdx * adjx + dgdy * adjy) + FIXED_HALF;
-                  fdgOuter = SignedFloatToFixed(dgdy + dxOuter * dgdx);
-                  fb = (GLfixed) (ChanToFixed(vLower->color[BCOMP])
-                                    + dbdx * adjx + dbdy * adjy) + FIXED_HALF;
-                  fdbOuter = SignedFloatToFixed(dbdy + dxOuter * dbdx);
+#  if CHAN_TYPE == GL_FLOAT
+                  rLeft = vLower->color[RCOMP] + (span.drdx * adjx + span.drdy * adjy) * (1.0F / FIXED_SCALE);
+                  gLeft = vLower->color[GCOMP] + (span.dgdx * adjx + span.dgdy * adjy) * (1.0F / FIXED_SCALE);
+                  bLeft = vLower->color[BCOMP] + (span.dbdx * adjx + span.dbdy * adjy) * (1.0F / FIXED_SCALE);
+                  fdrOuter = span.drdy + dxOuter * span.drdx;
+                  fdgOuter = span.dgdy + dxOuter * span.dgdx;
+                  fdbOuter = span.dbdy + dxOuter * span.dbdx;
+#  else
+                  rLeft = (GLint)(ChanToFixed(vLower->color[RCOMP]) + span.drdx * adjx + span.drdy * adjy) + FIXED_HALF;
+                  gLeft = (GLint)(ChanToFixed(vLower->color[GCOMP]) + span.dgdx * adjx + span.dgdy * adjy) + FIXED_HALF;
+                  bLeft = (GLint)(ChanToFixed(vLower->color[BCOMP]) + span.dbdx * adjx + span.dbdy * adjy) + FIXED_HALF;
+                  fdrOuter = SignedFloatToFixed(span.drdy + dxOuter * span.drdx);
+                  fdgOuter = SignedFloatToFixed(span.dgdy + dxOuter * span.dgdx);
+                  fdbOuter = SignedFloatToFixed(span.dbdy + dxOuter * span.dbdx);
+#  endif
 #  ifdef INTERP_ALPHA
-                  fa = (GLfixed) (ChanToFixed(vLower->color[ACOMP])
-                                   + dadx * adjx + dady * adjy) + FIXED_HALF;
-                  fdaOuter = SignedFloatToFixed(dady + dxOuter * dadx);
+#    if CHAN_TYPE == GL_FLOAT
+                  aLeft = vLower->color[ACOMP] + (span.dadx * adjx + span.dady * adjy) * (1.0F / FIXED_SCALE);
+                  fdaOuter = span.dady + dxOuter * span.dadx;
+#    else
+                  aLeft = (GLint)(ChanToFixed(vLower->color[ACOMP]) + span.dadx * adjx + span.dady * adjy) + FIXED_HALF;
+                  fdaOuter = SignedFloatToFixed(span.dady + dxOuter * span.dadx);
+#    endif
 #  endif
                }
                else {
                   ASSERT (ctx->Light.ShadeModel == GL_FLAT);
-                  fr = ChanToFixed(v2->color[RCOMP]);
-                  fg = ChanToFixed(v2->color[GCOMP]);
-                  fb = ChanToFixed(v2->color[BCOMP]);
+#  if CHAN_TYPE == GL_FLOAT
+                  rLeft = v2->color[RCOMP];
+                  gLeft = v2->color[GCOMP];
+                  bLeft = v2->color[BCOMP];
+                  fdrOuter = fdgOuter = fdbOuter = 0.0F;
+#  else
+                  rLeft = ChanToFixed(v2->color[RCOMP]);
+                  gLeft = ChanToFixed(v2->color[GCOMP]);
+                  bLeft = ChanToFixed(v2->color[BCOMP]);
                   fdrOuter = fdgOuter = fdbOuter = 0;
+#  endif
 #  ifdef INTERP_ALPHA
-                  fa =  ChanToFixed(v2->color[ACOMP]);
+#    if CHAN_TYPE == GL_FLOAT
+                  aLeft = v2->color[ACOMP];
+                  fdaOuter = 0.0F;
+#    else
+                  aLeft = ChanToFixed(v2->color[ACOMP]);
                   fdaOuter = 0;
+#    endif
 #  endif
                }
 #endif
-#ifdef INTERP_FLOAT_RGBA
-               if (ctx->Light.ShadeModel == GL_SMOOTH) {
-                  fr = vLower->color[RCOMP]
-                     + (drdx * adjx + drdy * adjy) * (1.0F / FIXED_SCALE);
-                  fdrOuter = drdy + dxOuter * drdx;
-                  fg = vLower->color[GCOMP]
-                     + (dgdx * adjx + dgdy * adjy) * (1.0F / FIXED_SCALE);
-                  fdgOuter = dgdy + dxOuter * dgdx;
-                  fb = vLower->color[BCOMP]
-                     + (dbdx * adjx + dbdy * adjy) * (1.0F / FIXED_SCALE);
-                  fdbOuter = dbdy + dxOuter * dbdx;
-                  fa = vLower->color[ACOMP]
-                     + (dadx * adjx + dady * adjy) * (1.0F / FIXED_SCALE);
-                  fdaOuter = dady + dxOuter * dadx;
-               }
-               else {
-                  fr = v2->color[RCOMP];
-                  fg = v2->color[GCOMP];
-                  fb = v2->color[BCOMP];
-                  fa = v2->color[ACOMP];
-                  fdrOuter = fdgOuter = fdbOuter = fdaOuter = 0.0F;
-               }
-#endif
+
 #ifdef INTERP_SPEC
                if (ctx->Light.ShadeModel == GL_SMOOTH) {
-                  fsr = (GLfixed) (ChanToFixed(vLower->specular[RCOMP])
-                                   + dsrdx * adjx + dsrdy * adjy) + FIXED_HALF;
-                  fdsrOuter = SignedFloatToFixed(dsrdy + dxOuter * dsrdx);
-                  fsg = (GLfixed) (ChanToFixed(vLower->specular[GCOMP])
-                                   + dsgdx * adjx + dsgdy * adjy) + FIXED_HALF;
-                  fdsgOuter = SignedFloatToFixed(dsgdy + dxOuter * dsgdx);
-                  fsb = (GLfixed) (ChanToFixed(vLower->specular[BCOMP])
-                                   + dsbdx * adjx + dsbdy * adjy) + FIXED_HALF;
-                  fdsbOuter = SignedFloatToFixed(dsbdy + dxOuter * dsbdx);
-               }
-               else {
-                  fsr = ChanToFixed(v2->specular[RCOMP]);
-                  fsg = ChanToFixed(v2->specular[GCOMP]);
-                  fsb = ChanToFixed(v2->specular[BCOMP]);
-                  fdsrOuter = fdsgOuter = fdsbOuter = 0;
-               }
-#endif
-#ifdef INTERP_FLOAT_SPEC
-               if (ctx->Light.ShadeModel == GL_SMOOTH) {
-                  fsr = vLower->specular[RCOMP]
-                     + (dsrdx * adjx + dsrdy * adjy) * (1.0F / FIXED_SCALE);
-                  fdsrOuter = dsrdy + dxOuter * dsrdx;
-                  fsg = vLower->specular[GCOMP]
-                     + (dsgdx * adjx + dsgdy * adjy) * (1.0F / FIXED_SCALE);
-                  fdsgOuter = dsgdy + dxOuter * dsgdx;
-                  fsb = vLower->specular[BCOMP]
-                     + (dsbdx * adjx + dsbdy * adjy) * (1.0F / FIXED_SCALE);
-                  fdsbOuter = dsbdy + dxOuter * dsbdx;
+#  if CHAN_TYPE == GL_FLOAT
+                  srLeft = vLower->specular[RCOMP] + (span.dsrdx * adjx + span.dsrdy * adjy) * (1.0F / FIXED_SCALE);
+                  sgLeft = vLower->specular[GCOMP] + (span.dsgdx * adjx + span.dsgdy * adjy) * (1.0F / FIXED_SCALE);
+                  sbLeft = vLower->specular[BCOMP] + (span.dsbdx * adjx + span.dsbdy * adjy) * (1.0F / FIXED_SCALE);
+                  dsrOuter = span.dsrdy + dxOuter * span.dsrdx;
+                  dsgOuter = span.dsgdy + dxOuter * span.dsgdx;
+                  dsbOuter = span.dsbdy + dxOuter * span.dsbdx;
+#  else
+                  srLeft = (GLfixed) (ChanToFixed(vLower->specular[RCOMP]) + span.dsrdx * adjx + span.dsrdy * adjy) + FIXED_HALF;
+                  sgLeft = (GLfixed) (ChanToFixed(vLower->specular[GCOMP]) + span.dsgdx * adjx + span.dsgdy * adjy) + FIXED_HALF;
+                  sbLeft = (GLfixed) (ChanToFixed(vLower->specular[BCOMP]) + span.dsbdx * adjx + span.dsbdy * adjy) + FIXED_HALF;
+                  dsrOuter = SignedFloatToFixed(span.dsrdy + dxOuter * span.dsrdx);
+                  dsgOuter = SignedFloatToFixed(span.dsgdy + dxOuter * span.dsgdx);
+                  dsbOuter = SignedFloatToFixed(span.dsbdy + dxOuter * span.dsbdx);
+#  endif
                }
                else {
-                  fsr = v2->specular[RCOMP];
-                  fsg = v2->specular[GCOMP];
-                  fsb = v2->specular[BCOMP];
-                  fdsrOuter = fdsgOuter = fdsbOuter = 0.0F;
+#if  CHAN_TYPE == GL_FLOAT
+                  srLeft = v2->specular[RCOMP];
+                  sgLeft = v2->specular[GCOMP];
+                  sbLeft = v2->specular[BCOMP];
+                  dsrOuter = dsgOuter = dsbOuter = 0.0F;
+#  else
+                  srLeft = ChanToFixed(v2->specular[RCOMP]);
+                  sgLeft = ChanToFixed(v2->specular[GCOMP]);
+                  sbLeft = ChanToFixed(v2->specular[BCOMP]);
+                  dsrOuter = dsgOuter = dsbOuter = 0;
+#  endif
                }
 #endif
+
 #ifdef INTERP_INDEX
                if (ctx->Light.ShadeModel == GL_SMOOTH) {
-                  fi = (GLfixed)(vLower->index * FIXED_SCALE
+                  iLeft = (GLfixed)(vLower->index * FIXED_SCALE
                                  + didx * adjx + didy * adjy) + FIXED_HALF;
-                  fdiOuter = SignedFloatToFixed(didy + dxOuter * didx);
+                  diOuter = SignedFloatToFixed(didy + dxOuter * didx);
                }
                else {
-                  fi = (GLfixed) (v2->index * FIXED_SCALE);
-                  fdiOuter = 0;
+                  iLeft = FloatToFixed(v2->index);
+                  diOuter = 0;
                }
 #endif
 #ifdef INTERP_INT_TEX
                {
                   GLfloat s0, t0;
                   s0 = vLower->texcoord[0][0] * S_SCALE;
-                  fs = (GLfixed)(s0 * FIXED_SCALE + dsdx * adjx
-                                 + dsdy * adjy) + FIXED_HALF;
-                  fdsOuter = SignedFloatToFixed(dsdy + dxOuter * dsdx);
+                  sLeft = (GLfixed)(s0 * FIXED_SCALE + span.texStepX[0][0] * adjx
+                                 + span.texStepY[0][0] * adjy) + FIXED_HALF;
+                  dsOuter = SignedFloatToFixed(span.texStepY[0][0] + dxOuter * span.texStepX[0][0]);
 
                   t0 = vLower->texcoord[0][1] * T_SCALE;
-                  ft = (GLfixed)(t0 * FIXED_SCALE + dtdx * adjx
-                                 + dtdy * adjy) + FIXED_HALF;
-                  fdtOuter = SignedFloatToFixed(dtdy + dxOuter * dtdx);
+                  tLeft = (GLfixed)(t0 * FIXED_SCALE + span.texStepX[0][1] * adjx
+                                 + span.texStepY[0][1] * adjy) + FIXED_HALF;
+                  dtOuter = SignedFloatToFixed(span.texStepY[0][1] + dxOuter * span.texStepX[0][1]);
                }
 #endif
 #ifdef INTERP_TEX
-               {
-                  GLfloat invW = vLower->win[3];
-                  GLfloat s0, t0, u0, v0;
-                  s0 = vLower->texcoord[0][0] * invW;
-                  sLeft = s0 + (span.texStepX[0][0] * adjx + dsdy * adjy)
-                     * (1.0F/FIXED_SCALE);
-                  dsOuter = dsdy + dxOuter * span.texStepX[0][0];
-                  t0 = vLower->texcoord[0][1] * invW;
-                  tLeft = t0 + (span.texStepX[0][1] * adjx + dtdy * adjy)
-                     * (1.0F/FIXED_SCALE);
-                  dtOuter = dtdy + dxOuter * span.texStepX[0][1];
-                  u0 = vLower->texcoord[0][2] * invW;
-                  uLeft = u0 + (span.texStepX[0][2] * adjx + dudy * adjy)
-                     * (1.0F/FIXED_SCALE);
-                  duOuter = dudy + dxOuter * span.texStepX[0][2];
-                  v0 = vLower->texcoord[0][3] * invW;
-                  vLeft = v0 + (span.texStepX[0][3] * adjx + dvdy * adjy)
-                     * (1.0F/FIXED_SCALE);
-                  dvOuter = dvdy + dxOuter * span.texStepX[0][3];
-               }
-#endif
-#ifdef INTERP_MULTITEX
-               {
-                  GLuint u;
-                  for (u = 0; u < ctx->Const.MaxTextureUnits; u++) {
-                     if (ctx->Texture.Unit[u]._ReallyEnabled) {
-                        GLfloat invW = vLower->win[3];
-                        GLfloat s0, t0, u0, v0;
-                        s0 = vLower->texcoord[u][0] * invW;
-                        sLeft[u] = s0 + (span.texStepX[u][0] * adjx + dsdy[u]
-                                         * adjy) * (1.0F/FIXED_SCALE);
-                        dsOuter[u] = dsdy[u] + dxOuter * span.texStepX[u][0];
-                        t0 = vLower->texcoord[u][1] * invW;
-                        tLeft[u] = t0 + (span.texStepX[u][1] * adjx + dtdy[u]
-                                         * adjy) * (1.0F/FIXED_SCALE);
-                        dtOuter[u] = dtdy[u] + dxOuter * span.texStepX[u][1];
-                        u0 = vLower->texcoord[u][2] * invW;
-                        uLeft[u] = u0 + (span.texStepX[u][2] * adjx + dudy[u]
-                                         * adjy) * (1.0F/FIXED_SCALE);
-                        duOuter[u] = dudy[u] + dxOuter * span.texStepX[u][2];
-                        v0 = vLower->texcoord[u][3] * invW;
-                        vLeft[u] = v0 + (span.texStepX[u][3] * adjx + dvdy[u]
-                                         * adjy) * (1.0F/FIXED_SCALE);
-                        dvOuter[u] = dvdy[u] + dxOuter * span.texStepX[u][3];
-                     }
-                  }
-               }
+               TEX_UNIT_LOOP(
+                  const GLfloat invW = vLower->win[3];
+                  const GLfloat s0 = vLower->texcoord[u][0] * invW;
+                  const GLfloat t0 = vLower->texcoord[u][1] * invW;
+                  const GLfloat u0 = vLower->texcoord[u][2] * invW;
+                  const GLfloat v0 = vLower->texcoord[u][3] * invW;
+                  sLeft[u] = s0 + (span.texStepX[u][0] * adjx + span.texStepY[u][0] * adjy) * (1.0F/FIXED_SCALE);
+                  tLeft[u] = t0 + (span.texStepX[u][1] * adjx + span.texStepY[u][1] * adjy) * (1.0F/FIXED_SCALE);
+                  uLeft[u] = u0 + (span.texStepX[u][2] * adjx + span.texStepY[u][2] * adjy) * (1.0F/FIXED_SCALE);
+                  vLeft[u] = v0 + (span.texStepX[u][3] * adjx + span.texStepY[u][3] * adjy) * (1.0F/FIXED_SCALE);
+                  dsOuter[u] = span.texStepY[u][0] + dxOuter * span.texStepX[u][0];
+                  dtOuter[u] = span.texStepY[u][1] + dxOuter * span.texStepX[u][1];
+                  duOuter[u] = span.texStepY[u][2] + dxOuter * span.texStepX[u][2];
+                  dvOuter[u] = span.texStepY[u][3] + dxOuter * span.texStepX[u][3];
+               )
 #endif
-
             } /*if setupLeft*/
 
 
             if (setupRight && eRight->lines>0) {
+#if TRIANGLE_WALK_DOUBLE
+               fxRightEdge = eRight->fsx;
+               fdxRightEdge = eRight->dxdy;
+#else
                fxRightEdge = eRight->fsx - FIXED_EPSILON;
                fdxRightEdge = eRight->fdxdy;
+#endif
             }
 
             if (lines==0) {
@@ -1078,55 +1025,46 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #  endif
             fdzInner = fdzOuter + span.zStep;
 #endif
+#ifdef INTERP_W
+            dwInner = dwOuter + span.dwdx;
+#endif
 #ifdef INTERP_FOG
-            dfogInner = dfogOuter + span.fogStep;
+            dfogInner = dfogOuter + span.dfogdx;
 #endif
-#if defined(INTERP_RGB) || defined(INTERP_FLOAT_RGBA)
+#ifdef INTERP_RGB
             fdrInner = fdrOuter + span.redStep;
             fdgInner = fdgOuter + span.greenStep;
             fdbInner = fdbOuter + span.blueStep;
 #endif
-#if defined(INTERP_ALPHA) || defined(INTERP_FLOAT_RGBA)
+#ifdef INTERP_ALPHA
             fdaInner = fdaOuter + span.alphaStep;
 #endif
-#if defined(INTERP_SPEC) || defined(INTERP_FLOAT_SPEC)
-            fdsrInner = fdsrOuter + span.specRedStep;
-            fdsgInner = fdsgOuter + span.specGreenStep;
-            fdsbInner = fdsbOuter + span.specBlueStep;
+#ifdef INTERP_SPEC
+            dsrInner = dsrOuter + span.specRedStep;
+            dsgInner = dsgOuter + span.specGreenStep;
+            dsbInner = dsbOuter + span.specBlueStep;
 #endif
 #ifdef INTERP_INDEX
-            fdiInner = fdiOuter + span.indexStep;
+            diInner = diOuter + span.indexStep;
 #endif
 #ifdef INTERP_INT_TEX
-            fdsInner = fdsOuter + span.intTexStep[0];
-            fdtInner = fdtOuter + span.intTexStep[1];
+            dsInner = dsOuter + span.intTexStep[0];
+            dtInner = dtOuter + span.intTexStep[1];
 #endif
 #ifdef INTERP_TEX
-            dsInner = dsOuter + span.texStepX[0][0];
-            dtInner = dtOuter + span.texStepX[0][1];
-            duInner = duOuter + span.texStepX[0][2];
-            dvInner = dvOuter + span.texStepX[0][3];
-#endif
-#ifdef INTERP_MULTITEX
-            {
-               GLuint u;
-               for (u = 0; u < ctx->Const.MaxTextureUnits; u++) {
-                  if (ctx->Texture.Unit[u]._ReallyEnabled) {
-                     dsInner[u] = dsOuter[u] + span.texStepX[u][0];
-                     dtInner[u] = dtOuter[u] + span.texStepX[u][1];
-                     duInner[u] = duOuter[u] + span.texStepX[u][2];
-                     dvInner[u] = dvOuter[u] + span.texStepX[u][3];
-                  }
-               }
-            }
+            TEX_UNIT_LOOP(
+               dsInner[u] = dsOuter[u] + span.texStepX[u][0];
+               dtInner[u] = dtOuter[u] + span.texStepX[u][1];
+               duInner[u] = duOuter[u] + span.texStepX[u][2];
+               dvInner[u] = dvOuter[u] + span.texStepX[u][3];
+            )
 #endif
 
             while (lines > 0) {
                /* initialize the span interpolants to the leftmost value */
                /* ff = fixed-pt fragment */
-               const GLint right = FixedToInt(fxRightEdge);
-
-               span.x = FixedToInt(fxLeftEdge);
+               const GLint right = InterpToInt(fxRightEdge);
+               span.x = InterpToInt(fxLeftEdge);
 
                if (right <= span.x)
                   span.end = 0;
@@ -1134,115 +1072,109 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
                   span.end = right - span.x;
 
 #ifdef INTERP_Z
-               span.z = fz;
+               span.z = zLeft;
+#endif
+#ifdef INTERP_W
+               span.w = wLeft;
 #endif
 #ifdef INTERP_FOG
                span.fog = fogLeft;
 #endif
-#if defined(INTERP_RGB) || defined(INTERP_FLOAT_RGBA)
-               span.red = fr;
-               span.green = fg;
-               span.blue = fb;
+#ifdef INTERP_RGB
+               span.red = rLeft;
+               span.green = gLeft;
+               span.blue = bLeft;
 #endif
-#if defined(INTERP_ALPHA) || defined(INTERP_FLOAT_RGBA)
-               span.alpha = fa;
+#ifdef INTERP_ALPHA
+               span.alpha = aLeft;
 #endif
-#if defined(INTERP_SPEC) || defined(INTERP_FLOAT_SPEC)
-               span.specRed = fsr;
-               span.specGreen = fsg;
-               span.specBlue = fsb;
+#ifdef INTERP_SPEC
+               span.specRed = srLeft;
+               span.specGreen = sgLeft;
+               span.specBlue = sbLeft;
 #endif
 #ifdef INTERP_INDEX
-               span.index = fi;
+               span.index = iLeft;
 #endif
 #ifdef INTERP_INT_TEX
-               span.intTex[0] = fs;
-               span.intTex[1] = ft;
+               span.intTex[0] = sLeft;
+               span.intTex[1] = tLeft;
 #endif
 
 #ifdef INTERP_TEX
-               span.tex[0][0] = sLeft;
-               span.tex[0][1] = tLeft;
-               span.tex[0][2] = uLeft;
-               span.tex[0][3] = vLeft;
-#endif
-
-#ifdef INTERP_MULTITEX
-               {
-                  GLuint u;
-                  for (u = 0; u < ctx->Const.MaxTextureUnits; u++) {
-                     if (ctx->Texture.Unit[u]._ReallyEnabled) {
-                        span.tex[u][0] = sLeft[u];
-                        span.tex[u][1] = tLeft[u];
-                        span.tex[u][2] = uLeft[u];
-                        span.tex[u][3] = vLeft[u];
-                     }
-                  }
-               }
-#endif
-
+               TEX_UNIT_LOOP(
+                  span.tex[u][0] = sLeft[u];
+                  span.tex[u][1] = tLeft[u];
+                  span.tex[u][2] = uLeft[u];
+                  span.tex[u][3] = vLeft[u];
+               )
+#endif
+
+               if (span.end > 1) {
+                  /* Under rare circumstances, we might have to fudge the
+                   * colors. XXX does this really happen anymore???
+                   */
+                  const GLint len = span.end - 1;
+                  (void) len;
 #ifdef INTERP_RGB
-               {
-                  /* need this to accomodate round-off errors */
-                  const GLint len = right - span.x - 1;
-                  GLfixed ffrend = span.red + len * span.redStep;
-                  GLfixed ffgend = span.green + len * span.greenStep;
-                  GLfixed ffbend = span.blue + len * span.blueStep;
-                  if (ffrend < 0) {
-                     span.red -= ffrend;
-                     if (span.red < 0)
-                        span.red = 0;
-                  }
-                  if (ffgend < 0) {
-                     span.green -= ffgend;
-                     if (span.green < 0)
-                        span.green = 0;
-                  }
-                  if (ffbend < 0) {
-                     span.blue -= ffbend;
-                     if (span.blue < 0)
-                        span.blue = 0;
+                  {
+                     GLfixed ffrend = span.red + len * span.redStep;
+                     GLfixed ffgend = span.green + len * span.greenStep;
+                     GLfixed ffbend = span.blue + len * span.blueStep;
+                     if (ffrend < 0) {
+                        span.red -= ffrend;
+                        if (span.red < 0)
+                           span.red = 0;
+                     }
+                     if (ffgend < 0) {
+                        span.green -= ffgend;
+                        if (span.green < 0)
+                           span.green = 0;
+                     }
+                     if (ffbend < 0) {
+                        span.blue -= ffbend;
+                        if (span.blue < 0)
+                           span.blue = 0;
+                     }
                   }
-               }
 #endif
 #ifdef INTERP_ALPHA
-               {
-                  const GLint len = right - span.x - 1;
-                  GLfixed ffaend = span.alpha + len * span.alphaStep;
-                  if (ffaend < 0) {
-                     span.alpha -= ffaend;
-                     if (span.alpha < 0)
-                        span.alpha = 0;
+                  {
+                     GLfixed ffaend = span.alpha + len * span.alphaStep;
+                     if (ffaend < 0) {
+                        span.alpha -= ffaend;
+                        if (span.alpha < 0)
+                           span.alpha = 0;
+                     }
                   }
-               }
 #endif
 #ifdef INTERP_SPEC
-               {
-                  /* need this to accomodate round-off errors */
-                  const GLint len = right - span.x - 1;
-                  GLfixed ffsrend = span.specRed + len * span.specRedStep;
-                  GLfixed ffsgend = span.specGreen + len * span.specGreenStep;
-                  GLfixed ffsbend = span.specBlue + len * span.specBlueStep;
-                  if (ffsrend < 0) {
-                     span.specRed -= ffsrend;
-                     if (span.specRed < 0)
-                        span.specRed = 0;
-                  }
-                  if (ffsgend < 0) {
-                     span.specGreen -= ffsgend;
-                     if (span.specGreen < 0)
-                        span.specGreen = 0;
-                  }
-                  if (ffsbend < 0) {
-                     span.specBlue -= ffsbend;
-                     if (span.specBlue < 0)
-                        span.specBlue = 0;
+                  {
+                     GLfixed ffsrend = span.specRed + len * span.specRedStep;
+                     GLfixed ffsgend = span.specGreen + len * span.specGreenStep;
+                     GLfixed ffsbend = span.specBlue + len * span.specBlueStep;
+                     if (ffsrend < 0) {
+                        span.specRed -= ffsrend;
+                        if (span.specRed < 0)
+                           span.specRed = 0;
+                     }
+                     if (ffsgend < 0) {
+                        span.specGreen -= ffsgend;
+                        if (span.specGreen < 0)
+                           span.specGreen = 0;
+                     }
+                     if (ffsbend < 0) {
+                        span.specBlue -= ffsbend;
+                        if (span.specBlue < 0)
+                           span.specBlue = 0;
+                     }
                   }
-               }
 #endif
 #ifdef INTERP_INDEX
-               if (span.index < 0)  span.index = 0;
+                  if (span.index < 0)
+                     span.index = 0;
 #endif
+               } /* span.end > 1 */
 
                /* This is where we actually generate fragments */
                if (span.end > 0) {
@@ -1255,16 +1187,16 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
                 * pixel-center x coordinate so that it stays
                 * on or inside the major edge.
                 */
-               (span.y)++;
+               span.y++;
                lines--;
 
                fxLeftEdge += fdxLeftEdge;
                fxRightEdge += fdxRightEdge;
 
-
                fError += fdError;
                if (fError >= 0) {
-                  fError -= FIXED_ONE;
+                  fError -= INTERP_ONE;
+
 #ifdef PIXEL_ADDRESS
                   pRow = (PIXEL_TYPE *) ((GLubyte *) pRow + dPRowOuter);
 #endif
@@ -1272,49 +1204,41 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #  ifdef DEPTH_TYPE
                   zRow = (DEPTH_TYPE *) ((GLubyte *) zRow + dZRowOuter);
 #  endif
-                  fz += fdzOuter;
+                  zLeft += fdzOuter;
+#endif
+#ifdef INTERP_W
+                  wLeft += dwOuter;
 #endif
 #ifdef INTERP_FOG
                   fogLeft += dfogOuter;
 #endif
-#if defined(INTERP_RGB) || defined(INTERP_FLOAT_RGBA)
-                  fr += fdrOuter;
-                  fg += fdgOuter;
-                  fb += fdbOuter;
+#ifdef INTERP_RGB
+                  rLeft += fdrOuter;
+                  gLeft += fdgOuter;
+                  bLeft += fdbOuter;
 #endif
-#if defined(INTERP_ALPHA) || defined(INTERP_FLOAT_RGBA)
-                  fa += fdaOuter;
+#ifdef INTERP_ALPHA
+                  aLeft += fdaOuter;
 #endif
-#if defined(INTERP_SPEC) || defined(INTERP_FLOAT_SPEC)
-                  fsr += fdsrOuter;
-                  fsg += fdsgOuter;
-                  fsb += fdsbOuter;
+#ifdef INTERP_SPEC
+                  srLeft += dsrOuter;
+                  sgLeft += dsgOuter;
+                  sbLeft += dsbOuter;
 #endif
 #ifdef INTERP_INDEX
-                  fi += fdiOuter;
+                  iLeft += diOuter;
 #endif
 #ifdef INTERP_INT_TEX
-                  fs += fdsOuter;
-                  ft += fdtOuter;
-#endif
-#ifdef INTERP_TEX
                   sLeft += dsOuter;
                   tLeft += dtOuter;
-                  uLeft += duOuter;
-                  vLeft += dvOuter;
 #endif
-#ifdef INTERP_MULTITEX
-                  {
-                     GLuint u;
-                     for (u = 0; u < ctx->Const.MaxTextureUnits; u++) {
-                        if (ctx->Texture.Unit[u]._ReallyEnabled) {
-                           sLeft[u] += dsOuter[u];
-                           tLeft[u] += dtOuter[u];
-                           uLeft[u] += duOuter[u];
-                           vLeft[u] += dvOuter[u];
-                        }
-                     }
-                  }
+#ifdef INTERP_TEX
+                  TEX_UNIT_LOOP(
+                     sLeft[u] += dsOuter[u];
+                     tLeft[u] += dtOuter[u];
+                     uLeft[u] += duOuter[u];
+                     vLeft[u] += dvOuter[u];
+                  )
 #endif
                }
                else {
@@ -1325,49 +1249,41 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #  ifdef DEPTH_TYPE
                   zRow = (DEPTH_TYPE *) ((GLubyte *) zRow + dZRowInner);
 #  endif
-                  fz += fdzInner;
+                  zLeft += fdzInner;
+#endif
+#ifdef INTERP_W
+                  wLeft += dwInner;
 #endif
 #ifdef INTERP_FOG
                   fogLeft += dfogInner;
 #endif
-#if defined(INTERP_RGB) || defined(INTERP_FLOAT_RGBA)
-                  fr += fdrInner;
-                  fg += fdgInner;
-                  fb += fdbInner;
+#ifdef INTERP_RGB
+                  rLeft += fdrInner;
+                  gLeft += fdgInner;
+                  bLeft += fdbInner;
 #endif
-#if defined(INTERP_ALPHA) || defined(INTERP_FLOAT_RGBA)
-                  fa += fdaInner;
+#ifdef INTERP_ALPHA
+                  aLeft += fdaInner;
 #endif
-#if defined(INTERP_SPEC) || defined(INTERP_FLOAT_SPEC)
-                  fsr += fdsrInner;
-                  fsg += fdsgInner;
-                  fsb += fdsbInner;
+#ifdef INTERP_SPEC
+                  srLeft += dsrInner;
+                  sgLeft += dsgInner;
+                  sbLeft += dsbInner;
 #endif
 #ifdef INTERP_INDEX
-                  fi += fdiInner;
+                  iLeft += diInner;
 #endif
 #ifdef INTERP_INT_TEX
-                  fs += fdsInner;
-                  ft += fdtInner;
-#endif
-#ifdef INTERP_TEX
                   sLeft += dsInner;
                   tLeft += dtInner;
-                  uLeft += duInner;
-                  vLeft += dvInner;
 #endif
-#ifdef INTERP_MULTITEX
-                  {
-                     GLuint u;
-                     for (u = 0; u < ctx->Const.MaxTextureUnits; u++) {
-                        if (ctx->Texture.Unit[u]._ReallyEnabled) {
-                           sLeft[u] += dsInner[u];
-                           tLeft[u] += dtInner[u];
-                           uLeft[u] += duInner[u];
-                           vLeft[u] += dvInner[u];
-                        }
-                     }
-                  }
+#ifdef INTERP_TEX
+                  TEX_UNIT_LOOP(
+                     sLeft[u] += dsInner[u];
+                     tLeft[u] += dtInner[u];
+                     uLeft[u] += duInner[u];
+                     vLeft[u] += dvInner[u];
+                  )
 #endif
                }
             } /*while lines>0*/
@@ -1390,6 +1306,7 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #undef PIXEL_ADDRESS
 
 #undef INTERP_Z
+#undef INTERP_W
 #undef INTERP_FOG
 #undef INTERP_RGB
 #undef INTERP_ALPHA
@@ -1398,13 +1315,15 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #undef INTERP_INT_TEX
 #undef INTERP_TEX
 #undef INTERP_MULTITEX
-#undef INTERP_FLOAT_RGBA
-#undef INTERP_FLOAT_SPEC
+#undef TEX_UNIT_LOOP
 
 #undef S_SCALE
 #undef T_SCALE
 
 #undef FixedToDepth
+#undef ColorTemp
+#undef GLinterp
+#undef InterpToInt
+#undef INTERP_ONE
 
-#undef DO_OCCLUSION_TEST
 #undef NAME