src/mesa/pipe/softpipe/sp_quad_stipple.c

   1
   2 /**
   3  * quad polygon stipple stage
   4  */
   5
   6 #include "sp_context.h"
   7 #include "sp_headers.h"
   8 #include "sp_quad.h"
   9 #include "pipe/p_defines.h"
  10 #include "pipe/p_util.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->prim == 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       if (softpipe->rasterizer->origin_lower_left) {
  28          y0 = softpipe->framebuffer.cbufs[0]->height - 1 - quad->y0;
  29          y1 = y0 - 1;
  30       }
  31       else {
  32          y0 = quad->y0;
  33          y1 = y0 + 1;
  34       }
  35       stipple0 = softpipe->poly_stipple.stipple[y0 % 32];
  36       stipple1 = softpipe->poly_stipple.stipple[y1 % 32];
  37
  38 #if 1
  39       const int col0 = quad->x0 % 32;
  40       if ((stipple0 & (bit31 >> col0)) == 0)
  41          quad->mask &= ~MASK_TOP_LEFT;
  42
  43       if ((stipple0 & (bit30 >> col0)) == 0)
  44          quad->mask &= ~MASK_TOP_RIGHT;
  45
  46       if ((stipple1 & (bit31 >> col0)) == 0)
  47          quad->mask &= ~MASK_BOTTOM_LEFT;
  48
  49       if ((stipple1 & (bit30 >> col0)) == 0)
  50          quad->mask &= ~MASK_BOTTOM_RIGHT;
  51 #else
  52       /* We'd like to use this code, but we'd need to redefine
  53        * MASK_TOP_LEFT to be (1 << 1) and MASK_TOP_RIGHT to be (1 << 0),
  54        * and similarly for the BOTTOM bits.  But that may have undesirable
  55        * side effects elsewhere.
  56        */
  57       const int col0 = 30 - (quad->x0 % 32);
  58       quad->mask &= (((stipple0 >> col0) & 0x3) |
  59                      (((stipple1 >> col0) & 0x3) << 2));
  60 #endif
  61       if (!quad->mask)
  62          return;
  63    }
  64
  65    qs->next->run(qs->next, quad);
  66 }
  67
  68
  69 static void stipple_begin(struct quad_stage *qs)
  70 {
  71    qs->next->begin(qs->next);
  72 }
  73
  74
  75 static void stipple_destroy(struct quad_stage *qs)
  76 {
  77    FREE( qs );
  78 }
  79
  80
  81 struct quad_stage *
  82 sp_quad_polygon_stipple_stage( struct softpipe_context *softpipe )
  83 {
  84    struct quad_stage *stage = CALLOC_STRUCT(quad_stage);
  85
  86    stage->softpipe = softpipe;
  87    stage->begin = stipple_begin;
  88    stage->run = stipple_quad;
  89    stage->destroy = stipple_destroy;
  90
  91    return stage;
  92 }