s_tritemp.h

mesa-6.5-minigui源码

       * cracks and overlaps.  A pixel is considered inside a
       * subtriangle if it meets all of four conditions: it is on or
       * to the right of the left edge, strictly to the left of the
       * right edge, on or below the top edge, and strictly above
       * the bottom edge.  (Some edges may be degenerate.)
       *
       * The following discussion assumes left-to-right scanning
       * (that is, the major edge is on the left); the right-to-left
       * case is a straightforward variation.
       *
       * We start by finding the half-integral y coordinate that is
       * at or below the top of the triangle.  This gives us the
       * first scan line that could possibly contain pixels that are
       * inside the triangle.
       *
       * Next we creep down the major edge until we reach that y,
       * and compute the corresponding x coordinate on the edge.
       * Then we find the half-integral x that lies on or just
       * inside the edge.  This is the first pixel that might lie in
       * the interior of the triangle.  (We won't know for sure
       * until we check the other edges.)
       *
       * As we rasterize the triangle, we'll step down the major
       * edge.  For each step in y, we'll move an integer number
       * of steps in x.  There are two possible x step sizes, which
       * we'll call the ``inner'' step (guaranteed to land on the
       * edge or inside it) and the ``outer'' step (guaranteed to
       * land on the edge or outside it).  The inner and outer steps
       * differ by one.  During rasterization we maintain an error
       * term that indicates our distance from the true edge, and
       * select either the inner step or the outer step, whichever
       * gets us to the first pixel that falls inside the triangle.
       *
       * All parameters (z, red, etc.) as well as the buffer
       * addresses for color and z have inner and outer step values,
       * so that we can increment them appropriately.  This method
       * eliminates the need to adjust parameters by creeping a
       * sub-pixel amount into the triangle at each scanline.
       */

      {
         GLint subTriangle;
         GLinterp fxLeftEdge = 0, fxRightEdge = 0;
         GLinterp fdxLeftEdge = 0, fdxRightEdge = 0;
         GLinterp fError = 0, fdError = 0;
#ifdef PIXEL_ADDRESS
         PIXEL_TYPE *pRow = NULL;
         GLint dPRowOuter = 0, dPRowInner;  /* offset in bytes */
#endif
#ifdef INTERP_Z
#  ifdef DEPTH_TYPE
         struct gl_renderbuffer *zrb
            = ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
         DEPTH_TYPE *zRow = NULL;
         GLint dZRowOuter = 0, dZRowInner;  /* offset in bytes */
#  endif
         GLuint zLeft = 0;
         GLfixed 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
         ColorTemp rLeft = 0, fdrOuter = 0, fdrInner;
         ColorTemp gLeft = 0, fdgOuter = 0, fdgInner;
         ColorTemp bLeft = 0, fdbOuter = 0, fdbInner;
#endif
#ifdef INTERP_ALPHA
         ColorTemp aLeft = 0, fdaOuter = 0, fdaInner;
#endif
#ifdef INTERP_SPEC
         ColorTemp srLeft=0, dsrOuter=0, dsrInner;
         ColorTemp sgLeft=0, dsgOuter=0, dsgInner;
         ColorTemp sbLeft=0, dsbOuter=0, dsbInner;
#endif
#ifdef INTERP_INDEX
         GLfixed iLeft=0, diOuter=0, diInner;
#endif
#ifdef INTERP_INT_TEX
         GLfixed sLeft=0, dsOuter=0, dsInner;
         GLfixed tLeft=0, dtOuter=0, dtInner;
#endif
#ifdef INTERP_TEX
         GLfloat sLeft[MAX_TEXTURE_COORD_UNITS];
         GLfloat tLeft[MAX_TEXTURE_COORD_UNITS];
         GLfloat uLeft[MAX_TEXTURE_COORD_UNITS];
         GLfloat vLeft[MAX_TEXTURE_COORD_UNITS];
         GLfloat dsOuter[MAX_TEXTURE_COORD_UNITS], dsInner[MAX_TEXTURE_COORD_UNITS];
         GLfloat dtOuter[MAX_TEXTURE_COORD_UNITS], dtInner[MAX_TEXTURE_COORD_UNITS];
         GLfloat duOuter[MAX_TEXTURE_COORD_UNITS], duInner[MAX_TEXTURE_COORD_UNITS];
         GLfloat dvOuter[MAX_TEXTURE_COORD_UNITS], dvInner[MAX_TEXTURE_COORD_UNITS];
#endif

         for (subTriangle=0; subTriangle<=1; subTriangle++) {
            EdgeT *eLeft, *eRight;
            int setupLeft, setupRight;
            int lines;

            if (subTriangle==0) {
               /* bottom half */
               if (scan_from_left_to_right) {
                  eLeft = &eMaj;
                  eRight = &eBot;
                  lines = eRight->lines;
                  setupLeft = 1;
                  setupRight = 1;
               }
               else {
                  eLeft = &eBot;
                  eRight = &eMaj;
                  lines = eLeft->lines;
                  setupLeft = 1;
                  setupRight = 1;
               }
            }
            else {
               /* top half */
               if (scan_from_left_to_right) {
                  eLeft = &eMaj;
                  eRight = &eTop;
                  lines = eRight->lines;
                  setupLeft = 0;
                  setupRight = 1;
               }
               else {
                  eLeft = &eTop;
                  eRight = &eMaj;
                  lines = eLeft->lines;
                  setupLeft = 1;
                  setupRight = 0;
               }
               if (lines == 0)
                  return;
            }

            if (setupLeft && eLeft->lines > 0) {
               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 = (GLfloat) idxOuter;
               span.y = FixedToInt(fsy);
#endif

               /* silence warnings on some compilers */
               (void) dxOuter;
               (void) adjx;
               (void) adjy;
               (void) vLower;

#ifdef PIXEL_ADDRESS
               {
                  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, 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
                * the triangle, we shouldn't overflow or underflow for any
                * pixel that's actually inside the triangle.
                */

#ifdef INTERP_Z
               {
                  GLfloat z0 = vLower->win[2];
                  if (depthBits <= 16) {
                     /* interpolate fixed-pt values */
                     GLfloat tmp = (z0 * FIXED_SCALE + span.dzdx * adjx
                                    + span.dzdy * adjy) + FIXED_HALF;
                     if (tmp < MAX_GLUINT / 2)
                        zLeft = (GLfixed) tmp;
                     else
                        zLeft = MAX_GLUINT / 2;
                     fdzOuter = SignedFloatToFixed(span.dzdy + dxOuter * span.dzdx);
                  }
                  else {
                     /* interpolate depth values w/out scaling */
                     zLeft = (GLuint) (z0 + span.dzdx * FixedToFloat(adjx)
                                       + span.dzdy * FixedToFloat(adjy));
                     fdzOuter = (GLint) (span.dzdy + dxOuter * span.dzdx);
                  }
#  ifdef DEPTH_TYPE
                  zRow = (DEPTH_TYPE *)
                    zrb->GetPointer(ctx, zrb, 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
#  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) {
#  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
#    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);
#  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
#    if CHAN_TYPE == GL_FLOAT
                  aLeft = v2->color[ACOMP];
                  fdaOuter = 0.0F;
#    else
                  aLeft = ChanToFixed(v2->color[ACOMP]);
                  fdaOuter = 0;
#    endif
#  endif
               }
#endif /* INTERP_RGB */


#ifdef INTERP_SPEC
               if (ctx->Light.ShadeModel == GL_SMOOTH) {
#  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 {
                  ASSERT(ctx->Light.ShadeModel == GL_FLAT);
#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) {
                  iLeft = (GLfixed)(vLower->index * FIXED_SCALE
                                 + didx * adjx + didy * adjy) + FIXED_HALF;