src/mesa/state_tracker/st_atom_stipple.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2007 VMware, Inc.
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  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
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  27
  28  /*
  29   * \brief polygon stipple state
  30   *
  31   * Authors:
  32   *   Brian Paul
  33   */
  34
  35
  36 #include <assert.h>
  37
  38 #include "st_context.h"
  39 #include "st_atom.h"
  40 #include "pipe/p_context.h"
  41 #include "pipe/p_defines.h"
  42
  43
  44 /**
  45  * OpenGL's polygon stipple is indexed with window coordinates in which
  46  * the origin (0,0) is the lower-left corner of the window.
  47  * With Gallium, the origin is the upper-left corner of the window.
  48  * To convert GL's polygon stipple to what gallium expects we need to
  49  * invert the pattern vertically and rotate the stipple rows according
  50  * to the window height.
  51  */
  52 static void
  53 invert_stipple(GLuint dest[32], const GLuint src[32], GLuint winHeight)
  54 {
  55    GLuint i;
  56
  57    for (i = 0; i < 32; i++) {
  58       dest[i] = src[(winHeight - 1 - i) & 0x1f];
  59    }
  60 }
  61
  62
  63 /** Update the stipple when the pattern or window height changes */
  64 void
  65 st_update_polygon_stipple( struct st_context *st )
  66 {
  67    const struct gl_context *ctx = st->ctx;
  68    const GLuint sz = sizeof(st->state.poly_stipple);
  69    assert(sz == sizeof(ctx->PolygonStipple));
  70
  71    if (memcmp(st->state.poly_stipple, ctx->PolygonStipple, sz)) {
  72       /* state has changed */
  73       struct pipe_poly_stipple newStipple;
  74
  75       memcpy(st->state.poly_stipple, ctx->PolygonStipple, sz);
  76
  77       if (!ctx->DrawBuffer->FlipY) {
  78          memcpy(newStipple.stipple, ctx->PolygonStipple, sizeof(newStipple.stipple));
  79       } else {
  80          invert_stipple(newStipple.stipple, ctx->PolygonStipple,
  81                         ctx->DrawBuffer->Height);
  82       }
  83
  84       st->pipe->set_polygon_stipple(st->pipe, &newStipple);
  85    }
  86 }