src/mesa/tnl/t_vb_cliptmp.h

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  6.5.2
   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    const GLuint v0_orig = v0;
 129
 130    if (mask & 0x3f) {
 131       LINE_CLIP( CLIP_RIGHT_BIT,  -1,  0,  0, 1 );
 132       LINE_CLIP( CLIP_LEFT_BIT,    1,  0,  0, 1 );
 133       LINE_CLIP( CLIP_TOP_BIT,     0, -1,  0, 1 );
 134       LINE_CLIP( CLIP_BOTTOM_BIT,  0,  1,  0, 1 );
 135       LINE_CLIP( CLIP_FAR_BIT,     0,  0, -1, 1 );
 136       LINE_CLIP( CLIP_NEAR_BIT,    0,  0,  1, 1 );
 137    }
 138
 139    if (mask & CLIP_USER_BIT) {
 140       for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
 141          if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
 142             const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
 143             const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
 144             const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
 145             const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
 146             LINE_CLIP( CLIP_USER_BIT, a, b, c, d );
 147          }
 148       }
 149    }
 150
 151    if (VB->ClipMask[v0]) {
 152       INTERP_4F( t0, coord[newvert], coord[v0], coord[v1] );
 153       interp( ctx, t0, newvert, v0, v1, GL_FALSE );
 154       v0 = newvert;
 155       newvert++;
 156    }
 157    else {
 158       ASSERT(t0 == 0.0);
 159    }
 160
 161    /* Note: we need to use vertex v0_orig when computing the new
 162     * interpolated/clipped vertex position, not the current v0 which
 163     * may have got set when we clipped the other end of the line!
 164     */
 165    if (VB->ClipMask[v1]) {
 166       INTERP_4F( t1, coord[newvert], coord[v1], coord[v0_orig] );
 167       interp( ctx, t1, newvert, v1, v0_orig, GL_FALSE );
 168
 169       if (ctx->Light.ShadeModel == GL_FLAT)
 170          tnl->Driver.Render.CopyPV( ctx, newvert, v1 );
 171
 172       v1 = newvert;
 173
 174       newvert++;
 175    }
 176    else {
 177       ASSERT(t1 == 0.0);
 178    }
 179
 180    tnl->Driver.Render.ClippedLine( ctx, v0, v1 );
 181 }
 182
 183
 184 /* Clip a triangle against the viewport and user clip planes.
 185  */
 186 static INLINE void
 187 TAG(clip_tri)( GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLubyte mask )
 188 {
 189    TNLcontext *tnl = TNL_CONTEXT(ctx);
 190    struct vertex_buffer *VB = &tnl->vb;
 191    tnl_interp_func interp = tnl->Driver.Render.Interp;
 192    GLuint newvert = VB->Count;
 193    GLfloat (*coord)[4] = VB->ClipPtr->data;
 194    GLuint pv = v2;
 195    GLuint vlist[2][MAX_CLIPPED_VERTICES];
 196    GLuint *inlist = vlist[0], *outlist = vlist[1];
 197    GLuint p;
 198    GLuint n = 3;
 199
 200    ASSIGN_3V(inlist, v2, v0, v1 ); /* pv rotated to slot zero */
 201
 202    if (mask & 0x3f) {
 203       POLY_CLIP( CLIP_RIGHT_BIT,  -1,  0,  0, 1 );
 204       POLY_CLIP( CLIP_LEFT_BIT,    1,  0,  0, 1 );
 205       POLY_CLIP( CLIP_TOP_BIT,     0, -1,  0, 1 );
 206       POLY_CLIP( CLIP_BOTTOM_BIT,  0,  1,  0, 1 );
 207       POLY_CLIP( CLIP_FAR_BIT,     0,  0, -1, 1 );
 208       POLY_CLIP( CLIP_NEAR_BIT,    0,  0,  1, 1 );
 209    }
 210
 211    if (mask & CLIP_USER_BIT) {
 212       for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
 213          if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
 214             const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
 215             const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
 216             const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
 217             const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
 218             POLY_CLIP( CLIP_USER_BIT, a, b, c, d );
 219          }
 220       }
 221    }
 222
 223    if (ctx->Light.ShadeModel == GL_FLAT) {
 224       if (pv != inlist[0]) {
 225          ASSERT( inlist[0] >= VB->Count );
 226          tnl->Driver.Render.CopyPV( ctx, inlist[0], pv );
 227       }
 228    }
 229
 230    tnl->Driver.Render.ClippedPolygon( ctx, inlist, n );
 231 }
 232
 233
 234 /* Clip a quad against the viewport and user clip planes.
 235  */
 236 static INLINE void
 237 TAG(clip_quad)( GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint v3,
 238                 GLubyte mask )
 239 {
 240    TNLcontext *tnl = TNL_CONTEXT(ctx);
 241    struct vertex_buffer *VB = &tnl->vb;
 242    tnl_interp_func interp = tnl->Driver.Render.Interp;
 243    GLuint newvert = VB->Count;
 244    GLfloat (*coord)[4] = VB->ClipPtr->data;
 245    GLuint pv = v3;
 246    GLuint vlist[2][MAX_CLIPPED_VERTICES];
 247    GLuint *inlist = vlist[0], *outlist = vlist[1];
 248    GLuint p;
 249    GLuint n = 4;
 250
 251    ASSIGN_4V(inlist, v3, v0, v1, v2 ); /* pv rotated to slot zero */
 252
 253    if (mask & 0x3f) {
 254       POLY_CLIP( CLIP_RIGHT_BIT,  -1,  0,  0, 1 );
 255       POLY_CLIP( CLIP_LEFT_BIT,    1,  0,  0, 1 );
 256       POLY_CLIP( CLIP_TOP_BIT,     0, -1,  0, 1 );
 257       POLY_CLIP( CLIP_BOTTOM_BIT,  0,  1,  0, 1 );
 258       POLY_CLIP( CLIP_FAR_BIT,     0,  0, -1, 1 );
 259       POLY_CLIP( CLIP_NEAR_BIT,    0,  0,  1, 1 );
 260    }
 261
 262    if (mask & CLIP_USER_BIT) {
 263       for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
 264          if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
 265             const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
 266             const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
 267             const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
 268             const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
 269             POLY_CLIP( CLIP_USER_BIT, a, b, c, d );
 270          }
 271       }
 272    }
 273
 274    if (ctx->Light.ShadeModel == GL_FLAT) {
 275       if (pv != inlist[0]) {
 276          ASSERT( inlist[0] >= VB->Count );
 277          tnl->Driver.Render.CopyPV( ctx, inlist[0], pv );
 278       }
 279    }
 280
 281    tnl->Driver.Render.ClippedPolygon( ctx, inlist, n );
 282 }
 283
 284 #undef W
 285 #undef Z
 286 #undef Y
 287 #undef X
 288 #undef SIZE
 289 #undef TAG
 290 #undef POLY_CLIP
 291 #undef LINE_CLIP