src/gallium/drivers/softpipe/sp_quad_stipple.c

   1
   2 /**
   3  * quad polygon stipple stage
   4  */
   5
   6 #include "sp_context.h"
   7 #include "sp_quad.h"
   8 #include "sp_quad_pipe.h"
   9 #include "pipe/p_defines.h"
  10 #include "util/u_memory.h"
  11
  12
  13 /**
  14  * Apply polygon stipple to quads produced by triangle rasterization
  15  */
  16 static void
  17 stipple_quad(struct quad_stage *qs, struct quad_header *quad)
  18 {
  19    static const uint bit31 = 1 << 31;
  20    static const uint bit30 = 1 << 30;
  21
  22    if (quad->input.prim == QUAD_PRIM_TRI) {
  23       struct softpipe_context *softpipe = qs->softpipe;
  24       /* need to invert Y to index into OpenGL's stipple pattern */
  25       int y0, y1;
  26       uint stipple0, stipple1;
  27       const int col0 = quad->input.x0 % 32;
  28
  29       if (softpipe->rasterizer->origin_lower_left) {
  30          y0 = softpipe->framebuffer.height - 1 - quad->input.y0;
  31          y1 = y0 - 1;
  32       }
  33       else {
  34          y0 = quad->input.y0;
  35          y1 = y0 + 1;
  36       }
  37
  38       stipple0 = softpipe->poly_stipple.stipple[y0 % 32];
  39       stipple1 = softpipe->poly_stipple.stipple[y1 % 32];
  40
  41       /* turn off quad mask bits that fail the stipple test */
  42       if ((stipple0 & (bit31 >> col0)) == 0)
  43          quad->inout.mask &= ~MASK_TOP_LEFT;
  44
  45       if ((stipple0 & (bit30 >> col0)) == 0)
  46          quad->inout.mask &= ~MASK_TOP_RIGHT;
  47
  48       if ((stipple1 & (bit31 >> col0)) == 0)
  49          quad->inout.mask &= ~MASK_BOTTOM_LEFT;
  50
  51       if ((stipple1 & (bit30 >> col0)) == 0)
  52          quad->inout.mask &= ~MASK_BOTTOM_RIGHT;
  53
  54       if (!quad->inout.mask) {
  55          /* all fragments failed stipple test, end of quad pipeline */
  56          return;
  57       }
  58    }
  59
  60    qs->next->run(qs->next, quad);
  61 }
  62
  63
  64 static void stipple_begin(struct quad_stage *qs)
  65 {
  66    qs->next->begin(qs->next);
  67 }
  68
  69
  70 static void stipple_destroy(struct quad_stage *qs)
  71 {
  72    FREE( qs );
  73 }
  74
  75
  76 struct quad_stage *
  77 sp_quad_polygon_stipple_stage( struct softpipe_context *softpipe )
  78 {
  79    struct quad_stage *stage = CALLOC_STRUCT(quad_stage);
  80
  81    stage->softpipe = softpipe;
  82    stage->begin = stipple_begin;
  83    stage->run = stipple_quad;
  84    stage->destroy = stipple_destroy;
  85
  86    return stage;
  87 }