src/mesa/tnl/t_vb_cliptmp.h

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  6.5.1
   4  *
   5  * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the "Software"),
   9  * to deal in the Software without restriction, including without limitation
  10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  11  * and/or sell copies of the Software, and to permit persons to whom the
  12  * Software is furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included
  15  * in all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  21  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  22  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23  *
  24  * Authors:
  25  *    Keith Whitwell <keith@tungstengraphics.com>
  26  */
  27
  28
  29 #define CLIP_DOTPROD(K, A, B, C, D) X(K)*A + Y(K)*B + Z(K)*C + W(K)*D
  30
  31 #define POLY_CLIP( PLANE_BIT, A, B, C, D )                              \
  32 do {                                                                    \
  33    if (mask & PLANE_BIT) {                                              \
  34       GLuint idxPrev = inlist[0];                                       \
  35       GLfloat dpPrev = CLIP_DOTPROD(idxPrev, A, B, C, D );              \
  36       GLuint outcount = 0;                                              \
  37       GLuint i;                                                         \
  38                                                                         \
  39       inlist[n] = inlist[0]; /* prevent rotation of vertices */         \
  40       for (i = 1; i <= n; i++) {                                        \
  41          GLuint idx = inlist[i];                                        \
  42          GLfloat dp = CLIP_DOTPROD(idx, A, B, C, D );                   \
  43                                                                         \
  44          if (!IS_NEGATIVE(dpPrev)) {                                    \
  45             outlist[outcount++] = idxPrev;                              \
  46          }                                                              \
  47                                                                         \
  48          if (DIFFERENT_SIGNS(dp, dpPrev)) {                             \
  49             if (IS_NEGATIVE(dp)) {                                      \
  50                /* Going out of bounds.  Avoid division by zero as we    \
  51                 * know dp != dpPrev from DIFFERENT_SIGNS, above.        \
  52                 */                                                      \
  53                GLfloat t = dp / (dp - dpPrev);                          \
  54                INTERP_4F( t, coord[newvert], coord[idx], coord[idxPrev]); \
  55                interp( ctx, t, newvert, idx, idxPrev, GL_TRUE );        \
  56             } else {                                                    \
  57                /* Coming back in.                                       \
  58                 */                                                      \
  59                GLfloat t = dpPrev / (dpPrev - dp);                      \
  60                INTERP_4F( t, coord[newvert], coord[idxPrev], coord[idx]); \
  61                interp( ctx, t, newvert, idxPrev, idx, GL_FALSE );       \
  62             }                                                           \
  63             outlist[outcount++] = newvert++;                            \
  64          }                                                              \
  65                                                                         \
  66          idxPrev = idx;                                                 \
  67          dpPrev = dp;                                                   \
  68       }                                                                 \
  69                                                                         \
  70       if (outcount < 3)                                                 \
  71          return;                                                        \
  72                                                                         \
  73       {                                                                 \
  74          GLuint *tmp = inlist;                                          \
  75          inlist = outlist;                                              \
  76          outlist = tmp;                                                 \
  77          n = outcount;                                                  \
  78       }                                                                 \
  79    }                                                                    \
  80 } while (0)
  81
  82
  83 #define LINE_CLIP(PLANE_BIT, A, B, C, D )                               \
  84 do {                                                                    \
  85    if (mask & PLANE_BIT) {                                              \
  86       const GLfloat dp0 = CLIP_DOTPROD( v0, A, B, C, D );               \
  87       const GLfloat dp1 = CLIP_DOTPROD( v1, A, B, C, D );               \
  88       const GLboolean neg_dp0 = IS_NEGATIVE(dp0);                       \
  89       const GLboolean neg_dp1 = IS_NEGATIVE(dp1);                       \
  90                                                                         \
  91       /* For regular clipping, we know from the clipmask that one       \
  92        * (or both) of these must be negative (otherwise we wouldn't     \
  93        * be here).                                                      \
  94        * For userclip, there is only a single bit for all active        \
  95        * planes, so we can end up here when there is nothing to do,     \
  96        * hence the second IS_NEGATIVE() test:                           \
  97        */                                                               \
  98       if (neg_dp0 && neg_dp1)                                           \
  99          return; /* both vertices outside clip plane: discard */        \
 100                                                                         \
 101       if (neg_dp1) {                                                    \
 102          GLfloat t = dp1 / (dp1 - dp0);                                 \
 103          if (t > t1) t1 = t;                                            \
 104       } else if (neg_dp0) {                                             \
 105          GLfloat t = dp0 / (dp0 - dp1);                                 \
 106          if (t > t0) t0 = t;                                            \
 107       }                                                                 \
 108       if (t0 + t1 >= 1.0)                                               \
 109          return; /* discard */                                          \
 110    }                                                                    \
 111 } while (0)
 112
 113
 114
 115 /* Clip a line against the viewport and user clip planes.
 116  */
 117 static INLINE void
 118 TAG(clip_line)( GLcontext *ctx, GLuint v0, GLuint v1, GLubyte mask )
 119 {
 120    TNLcontext *tnl = TNL_CONTEXT(ctx);
 121    struct vertex_buffer *VB = &tnl->vb;
 122    tnl_interp_func interp = tnl->Driver.Render.Interp;
 123    GLfloat (*coord)[4] = VB->ClipPtr->data;
 124    GLuint newvert = VB->Count;
 125    GLfloat t0 = 0;
 126    GLfloat t1 = 0;
 127    GLuint p;
 128
 129    if (mask & 0x3f) {
 130       LINE_CLIP( CLIP_RIGHT_BIT,  -1,  0,  0, 1 );
 131       LINE_CLIP( CLIP_LEFT_BIT,    1,  0,  0, 1 );
 132       LINE_CLIP( CLIP_TOP_BIT,     0, -1,  0, 1 );
 133       LINE_CLIP( CLIP_BOTTOM_BIT,  0,  1,  0, 1 );
 134       LINE_CLIP( CLIP_FAR_BIT,     0,  0, -1, 1 );
 135       LINE_CLIP( CLIP_NEAR_BIT,    0,  0,  1, 1 );
 136    }
 137
 138    if (mask & CLIP_USER_BIT) {
 139       for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
 140          if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
 141             const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
 142             const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
 143             const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
 144             const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
 145             LINE_CLIP( CLIP_USER_BIT, a, b, c, d );
 146          }
 147       }
 148    }
 149
 150    if (VB->ClipMask[v0]) {
 151       INTERP_4F( t0, coord[newvert], coord[v0], coord[v1] );
 152       interp( ctx, t0, newvert, v0, v1, GL_FALSE );
 153       v0 = newvert;
 154       newvert++;
 155    }
 156    else {
 157       ASSERT(t0 == 0.0);
 158    }
 159
 160    if (VB->ClipMask[v1]) {
 161       INTERP_4F( t1, coord[newvert], coord[v1], coord[v0] );
 162       interp( ctx, t1, newvert, v1, v0, GL_FALSE );
 163
 164       if (ctx->Light.ShadeModel == GL_FLAT)
 165          tnl->Driver.Render.CopyPV( ctx, newvert, v1 );
 166
 167       v1 = newvert;
 168
 169       newvert++;
 170    }
 171    else {
 172       ASSERT(t1 == 0.0);
 173    }
 174
 175    tnl->Driver.Render.ClippedLine( ctx, v0, v1 );
 176 }
 177
 178
 179 /* Clip a triangle against the viewport and user clip planes.
 180  */
 181 static INLINE void
 182 TAG(clip_tri)( GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLubyte mask )
 183 {
 184    TNLcontext *tnl = TNL_CONTEXT(ctx);
 185    struct vertex_buffer *VB = &tnl->vb;
 186    tnl_interp_func interp = tnl->Driver.Render.Interp;
 187    GLuint newvert = VB->Count;
 188    GLfloat (*coord)[4] = VB->ClipPtr->data;
 189    GLuint pv = v2;
 190    GLuint vlist[2][MAX_CLIPPED_VERTICES];
 191    GLuint *inlist = vlist[0], *outlist = vlist[1];
 192    GLuint p;
 193    GLuint n = 3;
 194
 195    ASSIGN_3V(inlist, v2, v0, v1 ); /* pv rotated to slot zero */
 196
 197    if (mask & 0x3f) {
 198       POLY_CLIP( CLIP_RIGHT_BIT,  -1,  0,  0, 1 );
 199       POLY_CLIP( CLIP_LEFT_BIT,    1,  0,  0, 1 );
 200       POLY_CLIP( CLIP_TOP_BIT,     0, -1,  0, 1 );
 201       POLY_CLIP( CLIP_BOTTOM_BIT,  0,  1,  0, 1 );
 202       POLY_CLIP( CLIP_FAR_BIT,     0,  0, -1, 1 );
 203       POLY_CLIP( CLIP_NEAR_BIT,    0,  0,  1, 1 );
 204    }
 205
 206    if (mask & CLIP_USER_BIT) {
 207       for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
 208          if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
 209             const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
 210             const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
 211             const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
 212             const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
 213             POLY_CLIP( CLIP_USER_BIT, a, b, c, d );
 214          }
 215       }
 216    }
 217
 218    if (ctx->Light.ShadeModel == GL_FLAT) {
 219       if (pv != inlist[0]) {
 220          ASSERT( inlist[0] >= VB->Count );
 221          tnl->Driver.Render.CopyPV( ctx, inlist[0], pv );
 222       }
 223    }
 224
 225    tnl->Driver.Render.ClippedPolygon( ctx, inlist, n );
 226 }
 227
 228
 229 /* Clip a quad against the viewport and user clip planes.
 230  */
 231 static INLINE void
 232 TAG(clip_quad)( GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint v3,
 233                 GLubyte mask )
 234 {
 235    TNLcontext *tnl = TNL_CONTEXT(ctx);
 236    struct vertex_buffer *VB = &tnl->vb;
 237    tnl_interp_func interp = tnl->Driver.Render.Interp;
 238    GLuint newvert = VB->Count;
 239    GLfloat (*coord)[4] = VB->ClipPtr->data;
 240    GLuint pv = v3;
 241    GLuint vlist[2][MAX_CLIPPED_VERTICES];
 242    GLuint *inlist = vlist[0], *outlist = vlist[1];
 243    GLuint p;
 244    GLuint n = 4;
 245
 246    ASSIGN_4V(inlist, v3, v0, v1, v2 ); /* pv rotated to slot zero */
 247
 248    if (mask & 0x3f) {
 249       POLY_CLIP( CLIP_RIGHT_BIT,  -1,  0,  0, 1 );
 250       POLY_CLIP( CLIP_LEFT_BIT,    1,  0,  0, 1 );
 251       POLY_CLIP( CLIP_TOP_BIT,     0, -1,  0, 1 );
 252       POLY_CLIP( CLIP_BOTTOM_BIT,  0,  1,  0, 1 );
 253       POLY_CLIP( CLIP_FAR_BIT,     0,  0, -1, 1 );
 254       POLY_CLIP( CLIP_NEAR_BIT,    0,  0,  1, 1 );
 255    }
 256
 257    if (mask & CLIP_USER_BIT) {
 258       for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
 259          if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
 260             const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
 261             const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
 262             const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
 263             const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
 264             POLY_CLIP( CLIP_USER_BIT, a, b, c, d );
 265          }
 266       }
 267    }
 268
 269    if (ctx->Light.ShadeModel == GL_FLAT) {
 270       if (pv != inlist[0]) {
 271          ASSERT( inlist[0] >= VB->Count );
 272          tnl->Driver.Render.CopyPV( ctx, inlist[0], pv );
 273       }
 274    }
 275
 276    tnl->Driver.Render.ClippedPolygon( ctx, inlist, n );
 277 }
 278
 279 #undef W
 280 #undef Z
 281 #undef Y
 282 #undef X
 283 #undef SIZE
 284 #undef TAG
 285 #undef POLY_CLIP
 286 #undef LINE_CLIP