sp_quad_stipple.c

/**
 * quad polygon stipple stage
 */

#include "sp_context.h"
#include "sp_quad.h"
#include "sp_quad_pipe.h"
#include "pipe/p_defines.h"
#include "util/u_memory.h"


/**
 * Apply polygon stipple to quads produced by triangle rasterization
 */
static void
stipple_quad(struct quad_stage *qs, struct quad_header *quads[], unsigned nr)
{
   static const uint bit31 = 1u << 31;
   static const uint bit30 = 1u << 30;
   unsigned pass = nr;

   struct softpipe_context *softpipe = qs->softpipe;
   unsigned q;

   pass = 0;

   for (q = 0; q < nr; q++)  {
      struct quad_header *quad = quads[q];

      const int col0 = quad->input.x0 % 32;
      const int y0 = quad->input.y0;
      const int y1 = y0 + 1;
      const uint stipple0 = softpipe->poly_stipple.stipple[y0 % 32];
      const uint stipple1 = softpipe->poly_stipple.stipple[y1 % 32];

      /* turn off quad mask bits that fail the stipple test */
      if ((stipple0 & (bit31 >> col0)) == 0)
         quad->inout.mask &= ~MASK_TOP_LEFT;

      if ((stipple0 & (bit30 >> col0)) == 0)
         quad->inout.mask &= ~MASK_TOP_RIGHT;

      if ((stipple1 & (bit31 >> col0)) == 0)
         quad->inout.mask &= ~MASK_BOTTOM_LEFT;

      if ((stipple1 & (bit30 >> col0)) == 0)
         quad->inout.mask &= ~MASK_BOTTOM_RIGHT;

      if (quad->inout.mask)
         quads[pass++] = quad;
   }

   qs->next->run(qs->next, quads, pass);
}


static void stipple_begin(struct quad_stage *qs)
{
   qs->next->begin(qs->next);
}


static void stipple_destroy(struct quad_stage *qs)
{
   FREE( qs );
}


struct quad_stage *
sp_quad_polygon_stipple_stage( struct softpipe_context *softpipe )
{
   struct quad_stage *stage = CALLOC_STRUCT(quad_stage);

   stage->softpipe = softpipe;
   stage->begin = stipple_begin;
   stage->run = stipple_quad;
   stage->destroy = stipple_destroy;

   return stage;
}