src/mesa/state_tracker/st_atom_msaa.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2010 VMware, Inc.
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  16  * of the Software.
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  26  **************************************************************************/
  27
  28
  29 #include "st_context.h"
  30 #include "pipe/p_context.h"
  31 #include "st_atom.h"
  32
  33 #include "cso_cache/cso_context.h"
  34 #include "util/u_framebuffer.h"
  35
  36
  37 /* Second state atom for user clip planes:
  38  */
  39 static void update_sample_mask( struct st_context *st )
  40 {
  41    unsigned sample_mask = 0xffffffff;
  42    struct pipe_framebuffer_state *framebuffer = &st->state.framebuffer;
  43    /* dependency here on bound surface (or rather, sample count) is worrying */
  44    unsigned sample_count = util_framebuffer_get_num_samples(framebuffer);
  45
  46    if (st->ctx->Multisample.Enabled && sample_count > 1) {
  47    /* unlike in gallium/d3d10 the mask is only active if msaa is enabled */
  48       if (st->ctx->Multisample.SampleCoverage) {
  49          unsigned nr_bits;
  50          nr_bits = (unsigned)
  51             (st->ctx->Multisample.SampleCoverageValue * (float)sample_count);
  52          /* there's lot of ways how to do this. We just use first few bits,
  53             since we have no knowledge of sample positions here. When
  54             app-supplied mask though is used too might need to be smarter.
  55             Also, there's a interface restriction here in theory it is
  56             encouraged this mask not be the same at each pixel. */
  57          sample_mask = (1 << nr_bits) - 1;
  58          if (st->ctx->Multisample.SampleCoverageInvert)
  59             sample_mask = ~sample_mask;
  60       }
  61       if (st->ctx->Multisample.SampleMask)
  62          sample_mask &= st->ctx->Multisample.SampleMaskValue;
  63    }
  64
  65    /* mask off unused bits or don't care? */
  66
  67    if (sample_mask != st->state.sample_mask) {
  68       st->state.sample_mask = sample_mask;
  69       cso_set_sample_mask(st->cso_context, sample_mask);
  70    }
  71 }
  72
  73
  74 const struct st_tracked_state st_update_msaa = {
  75    "st_update_msaa",                                    /* name */
  76    {                                                    /* dirty */
  77       (_NEW_MULTISAMPLE | _NEW_BUFFERS),                /* mesa */
  78       ST_NEW_FRAMEBUFFER,                               /* st */
  79    },
  80    update_sample_mask                                   /* update */
  81 };