mesa/src/gallium/drivers/llvmpipe/lp_rast_tri.c

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 *
 * Copyright 2007-2009 VMware, Inc.
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 *
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 * copy of this software and associated documentation files (the
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 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
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 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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/*
 * Rasterization for binned triangles within a tile
 */

#include "util/u_math.h"
#include "lp_rast_priv.h"
#include "lp_tile_soa.h"


#define BLOCKSIZE 8


/* Convert 8x8 block into four runs of quads and render each in turn.
 */
#if (BLOCKSIZE == 8)
static void block_full( struct lp_rasterizer *rast,
                        const struct lp_rast_triangle *tri,
                        int x, int y )
{
   const unsigned masks[4] = {~0, ~0, ~0, ~0};
   int iy;

   for (iy = 0; iy < 8; iy += 2)
      lp_rast_shade_quads(rast, &tri->inputs, x, y + iy, masks);
}
#else
static void block_full( struct lp_rasterizer *rast,
                        const struct lp_rast_triangle *tri,
                        int x, int y )
{
   const unsigned masks[4] = {~0, ~0, 0, 0}; /* FIXME: Wasting quads!!! */
   int iy;

   for (iy = 0; iy < 4; iy += 2)
      lp_rast_shade_quads(rast, &tri->inputs, x, y + iy, masks);
}
#endif

static INLINE unsigned
do_quad( const struct lp_rast_triangle *tri,
	 int x, int y,
	 float c1, float c2, float c3 )
{
   float xstep1 = -tri->dy12;
   float xstep2 = -tri->dy23;
   float xstep3 = -tri->dy31;

   float ystep1 = tri->dx12;
   float ystep2 = tri->dx23;
   float ystep3 = tri->dx31;

   unsigned mask = 0;

   if (c1 > 0 &&
       c2 > 0 &&
       c3 > 0)
      mask |= 1;
	 
   if (c1 + xstep1 > 0 && 
       c2 + xstep2 > 0 && 
       c3 + xstep3 > 0)
      mask |= 2;

   if (c1 + ystep1 > 0 && 
       c2 + ystep2 > 0 && 
       c3 + ystep3 > 0)
      mask |= 4;

   if (c1 + ystep1 + xstep1 > 0 && 
       c2 + ystep2 + xstep2 > 0 && 
       c3 + ystep3 + xstep3 > 0)
      mask |= 8;

   return mask;
}

/* Evaluate each pixel in a block, generate a mask and possibly render
 * the quad:
 */
static void
do_block( struct lp_rasterizer *rast,
          const struct lp_rast_triangle *tri,
          int x, int y,
          float c1,
          float c2,
          float c3 )
{
   const int step = 2;

   float xstep1 = -step * tri->dy12;
   float xstep2 = -step * tri->dy23;
   float xstep3 = -step * tri->dy31;

   float ystep1 = step * tri->dx12;
   float ystep2 = step * tri->dx23;
   float ystep3 = step * tri->dx31;

   int ix, iy;

   for (iy = 0; iy < BLOCKSIZE; iy += 2) {
      float cx1 = c1;
      float cx2 = c2;
      float cx3 = c3;

      unsigned masks[4] = {0, 0, 0, 0};

      for (ix = 0; ix < BLOCKSIZE; ix += 2) {

	 masks[ix >> 1] = do_quad(tri, x + ix, y + iy, cx1, cx2, cx3);

	 cx1 += xstep1;
	 cx2 += xstep2;
	 cx3 += xstep3;
      }

      lp_rast_shade_quads(rast, &tri->inputs, x, y + iy, masks);

      c1 += ystep1;
      c2 += ystep2;
      c3 += ystep3;
   }

}



/* Scan the tile in chunks and figure out which pixels to rasterize
 * for this triangle:
 */
void lp_rast_triangle( struct lp_rasterizer *rast,
                       const union lp_rast_cmd_arg *arg )
{
   const struct lp_rast_triangle *tri = arg->triangle;
   int minx, maxx, miny, maxy;

   /* Clamp to tile dimensions:
    */
   minx = MAX2(tri->maxx, rast->x);
   miny = MAX2(tri->miny, rast->y);
   maxx = MIN2(tri->maxx, rast->x + TILE_SIZE);
   maxy = MIN2(tri->maxy, rast->y + TILE_SIZE);

   if (miny == maxy ||
       minx == maxx) {
      debug_printf("%s: non-intersecting triangle in bin\n", __FUNCTION__);
      //assert(0);
      return;
   }

   const int step = BLOCKSIZE;

   float ei1 = tri->ei1 * step;
   float ei2 = tri->ei2 * step;
   float ei3 = tri->ei3 * step;

   float eo1 = tri->eo1 * step;
   float eo2 = tri->eo2 * step;
   float eo3 = tri->eo3 * step;

   float xstep1 = -step * tri->dy12;
   float xstep2 = -step * tri->dy23;
   float xstep3 = -step * tri->dy31;

   float ystep1 = step * tri->dx12;
   float ystep2 = step * tri->dx23;
   float ystep3 = step * tri->dx31;
   int x, y;

   minx &= ~(step-1);
   miny &= ~(step-1);

   for (y = miny; y < maxy; y += step)
   {
      float cx1 = c1;
      float cx2 = c2;
      float cx3 = c3;

      for (x = minx; x < maxx; x += step)
      {
         if (cx1 + eo1 < 0 ||
             cx2 + eo2 < 0 ||
             cx3 + eo3 < 0)
         {
         }
         else if (cx1 + ei1 > 0 &&
                  cx2 + ei2 > 0 &&
                  cx3 + ei3 > 0)
         {
            block_full(rast, tri, x, y); /* trivial accept */
         }
         else
         {
            do_block(rast, tri, x, y, cx1, cx2, cx3);
         }

         /* Iterate cx values across the region:
          */
         cx1 += xstep1;
         cx2 += xstep2;
         cx3 += xstep3;
      }

      /* Iterate c values down the region:
       */
      c1 += ystep1;
      c2 += ystep2;
      c3 += ystep3;
   }
}