/* Clip a line against the viewport and user clip planes.
 */
static void
do_clip_line( struct draw_stage *stage,
	      struct prim_header *header,
	      unsigned clipmask )
{
   const struct clip_stage *clipper = clip_stage( stage );
   struct vertex_header *v0 = header->v[0];
   struct vertex_header *v1 = header->v[1];
   float t0 = 0.0F;
   float t1 = 0.0F;
   struct prim_header newprim;

   while (clipmask) {
      const unsigned plane_idx = ffs(clipmask)-1;
      const float dp0 = getclipdist(clipper, v0, plane_idx);
      const float dp1 = getclipdist(clipper, v1, plane_idx);

      if (dp1 < 0.0F) {
	 float t = dp1 / (dp1 - dp0);
         t1 = MAX2(t1, t);
      } 

      if (dp0 < 0.0F) {
	 float t = dp0 / (dp0 - dp1);
         t0 = MAX2(t0, t);
      }

      if (t0 + t1 >= 1.0F)
	 return; /* discard */

      clipmask &= ~(1 << plane_idx);  /* turn off this plane's bit */
   }

   if (v0->clipmask) {
      interp( clipper, stage->tmp[0], t0, v0, v1 );
      copy_flat(stage, stage->tmp[0], v0);
      newprim.v[0] = stage->tmp[0];
   }
   else {
      newprim.v[0] = v0;
   }

   if (v1->clipmask) {
      interp( clipper, stage->tmp[1], t1, v1, v0 );
      newprim.v[1] = stage->tmp[1];
   }
   else {
      newprim.v[1] = v1;
   }

   stage->next->line( stage->next, &newprim );
}
Exemple #2
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/* Clip a line against the viewport and user clip planes.
 */
static void
do_clip_line( struct draw_stage *stage,
	      struct prim_header *header,
	      unsigned clipmask )
{
   const struct clip_stage *clipper = clip_stage( stage );
   struct vertex_header *v0 = header->v[0];
   struct vertex_header *v1 = header->v[1];
   float t0 = 0.0F;
   float t1 = 0.0F;
   struct prim_header newprim;
   int viewport_index = draw_viewport_index(clipper->stage.draw, v0);

   while (clipmask) {
      const unsigned plane_idx = ffs(clipmask)-1;
      const float dp0 = getclipdist(clipper, v0, plane_idx);
      const float dp1 = getclipdist(clipper, v1, plane_idx);

      if (util_is_inf_or_nan(dp0) || util_is_inf_or_nan(dp1))
         return; //discard nan

      if (dp1 < 0.0F) {
	 float t = dp1 / (dp1 - dp0);
         t1 = MAX2(t1, t);
      } 

      if (dp0 < 0.0F) {
	 float t = dp0 / (dp0 - dp1);
         t0 = MAX2(t0, t);
      }

      if (t0 + t1 >= 1.0F)
	 return; /* discard */

      clipmask &= ~(1 << plane_idx);  /* turn off this plane's bit */
   }

   if (v0->clipmask) {
      interp( clipper, stage->tmp[0], t0, v0, v1, viewport_index );
      if (stage->draw->rasterizer->flatshade_first) {
         copy_flat(stage, stage->tmp[0], v0);  /* copy v0 color to tmp[0] */
      }
      else {
         copy_flat(stage, stage->tmp[0], v1);  /* copy v1 color to tmp[0] */
      }
      newprim.v[0] = stage->tmp[0];
   }
   else {
      newprim.v[0] = v0;
   }

   if (v1->clipmask) {
      interp( clipper, stage->tmp[1], t1, v1, v0, viewport_index );
      if (stage->draw->rasterizer->flatshade_first) {
         copy_flat(stage, stage->tmp[1], v0);  /* copy v0 color to tmp[1] */
      }
      else {
         copy_flat(stage, stage->tmp[1], v1);  /* copy v1 color to tmp[1] */
      }
      newprim.v[1] = stage->tmp[1];
   }
   else {
      newprim.v[1] = v1;
   }

   stage->next->line( stage->next, &newprim );
}
Exemple #3
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/* Clip a triangle against the viewport and user clip planes.
 */
static void
do_clip_tri( struct draw_stage *stage, 
	     struct prim_header *header,
	     unsigned clipmask )
{
   struct clip_stage *clipper = clip_stage( stage );
   struct vertex_header *a[MAX_CLIPPED_VERTICES];
   struct vertex_header *b[MAX_CLIPPED_VERTICES];
   struct vertex_header **inlist = a;
   struct vertex_header **outlist = b;
   unsigned tmpnr = 0;
   unsigned n = 3;
   unsigned i;
   boolean aEdges[MAX_CLIPPED_VERTICES];
   boolean bEdges[MAX_CLIPPED_VERTICES];
   boolean *inEdges = aEdges;
   boolean *outEdges = bEdges;
   int viewport_index = 0;

   inlist[0] = header->v[0];
   inlist[1] = header->v[1];
   inlist[2] = header->v[2];

   viewport_index = draw_viewport_index(clipper->stage.draw, inlist[0]);

   if (DEBUG_CLIP) {
      const float *v0 = header->v[0]->clip;
      const float *v1 = header->v[1]->clip;
      const float *v2 = header->v[2]->clip;
      debug_printf("Clip triangle:\n");
      debug_printf(" %f, %f, %f, %f\n", v0[0], v0[1], v0[2], v0[3]);
      debug_printf(" %f, %f, %f, %f\n", v1[0], v1[1], v1[2], v1[3]);
      debug_printf(" %f, %f, %f, %f\n", v2[0], v2[1], v2[2], v2[3]);
   }

   /*
    * Note: at this point we can't just use the per-vertex edge flags.
    * We have to observe the edge flag bits set in header->flags which
    * were set during primitive decomposition.  Put those flags into
    * an edge flags array which parallels the vertex array.
    * Later, in the 'unfilled' pipeline stage we'll draw the edge if both
    * the header.flags bit is set AND the per-vertex edgeflag field is set.
    */
   inEdges[0] = !!(header->flags & DRAW_PIPE_EDGE_FLAG_0);
   inEdges[1] = !!(header->flags & DRAW_PIPE_EDGE_FLAG_1);
   inEdges[2] = !!(header->flags & DRAW_PIPE_EDGE_FLAG_2);

   while (clipmask && n >= 3) {
      const unsigned plane_idx = ffs(clipmask)-1;
      const boolean is_user_clip_plane = plane_idx >= 6;
      struct vertex_header *vert_prev = inlist[0];
      boolean *edge_prev = &inEdges[0];
      float dp_prev;
      unsigned outcount = 0;

      dp_prev = getclipdist(clipper, vert_prev, plane_idx);
      clipmask &= ~(1<<plane_idx);

      if (util_is_inf_or_nan(dp_prev))
         return; //discard nan

      assert(n < MAX_CLIPPED_VERTICES);
      if (n >= MAX_CLIPPED_VERTICES)
         return;
      inlist[n] = inlist[0]; /* prevent rotation of vertices */
      inEdges[n] = inEdges[0];

      for (i = 1; i <= n; i++) {
	 struct vertex_header *vert = inlist[i];
         boolean *edge = &inEdges[i];

         float dp = getclipdist(clipper, vert, plane_idx);

         if (util_is_inf_or_nan(dp))
            return; //discard nan

	 if (dp_prev >= 0.0f) {
            assert(outcount < MAX_CLIPPED_VERTICES);
            if (outcount >= MAX_CLIPPED_VERTICES)
               return;
            outEdges[outcount] = *edge_prev;
	    outlist[outcount++] = vert_prev;
	 }

	 if (DIFFERENT_SIGNS(dp, dp_prev)) {
	    struct vertex_header *new_vert;
            boolean *new_edge;

            assert(tmpnr < MAX_CLIPPED_VERTICES + 1);
            if (tmpnr >= MAX_CLIPPED_VERTICES + 1)
               return;
            new_vert = clipper->stage.tmp[tmpnr++];

            assert(outcount < MAX_CLIPPED_VERTICES);
            if (outcount >= MAX_CLIPPED_VERTICES)
               return;

            new_edge = &outEdges[outcount];
	    outlist[outcount++] = new_vert;

	    if (dp < 0.0f) {
	       /* Going out of bounds.  Avoid division by zero as we
		* know dp != dp_prev from DIFFERENT_SIGNS, above.
		*/
	       float t = dp / (dp - dp_prev);
	       interp( clipper, new_vert, t, vert, vert_prev, viewport_index );
	       
	       /* Whether or not to set edge flag for the new vert depends
                * on whether it's a user-defined clipping plane.  We're
                * copying NVIDIA's behaviour here.
		*/
               if (is_user_clip_plane) {
                  /* we want to see an edge along the clip plane */
                  *new_edge = TRUE;
                  new_vert->edgeflag = TRUE;
               }
               else {
                  /* we don't want to see an edge along the frustum clip plane */
                  *new_edge = *edge_prev;
                  new_vert->edgeflag = FALSE;
               }
	    }
            else {
	       /* Coming back in.
		*/
	       float t = dp_prev / (dp_prev - dp);
	       interp( clipper, new_vert, t, vert_prev, vert, viewport_index );

	       /* Copy starting vert's edgeflag:
		*/
	       new_vert->edgeflag = vert_prev->edgeflag;
               *new_edge = *edge_prev;
	    }
	 }

	 vert_prev = vert;
         edge_prev = edge;
	 dp_prev = dp;
      }

      /* swap in/out lists */
      {
	 struct vertex_header **tmp = inlist;
	 inlist = outlist;
	 outlist = tmp;
	 n = outcount;
      }
      {
         boolean *tmp = inEdges;
         inEdges = outEdges;
         outEdges = tmp;
      }

   }

   /* If flat-shading, copy provoking vertex color to polygon vertex[0]
    */
   if (n >= 3) {
      if (clipper->num_flat_attribs) {
         if (stage->draw->rasterizer->flatshade_first) {
            if (inlist[0] != header->v[0]) {
               assert(tmpnr < MAX_CLIPPED_VERTICES + 1);
               if (tmpnr >= MAX_CLIPPED_VERTICES + 1)
                  return;
               inlist[0] = dup_vert(stage, inlist[0], tmpnr++);
               copy_flat(stage, inlist[0], header->v[0]);
            }
         }
         else {
            if (inlist[0] != header->v[2]) {
               assert(tmpnr < MAX_CLIPPED_VERTICES + 1);
               if (tmpnr >= MAX_CLIPPED_VERTICES + 1)
                  return;
               inlist[0] = dup_vert(stage, inlist[0], tmpnr++);
               copy_flat(stage, inlist[0], header->v[2]);
            }
         }
      }
      
      /* Emit the polygon as triangles to the setup stage:
       */
      emit_poly( stage, inlist, inEdges, n, header );
   }
}