Mesa (floating): softpipe: respect fragment clamping and turn on ARB_color_buffer_float

[Luca Barbieri]

Module: Mesa
Branch: floating
Commit: 6e25b30ca70a2b481bd3232d45b6d854808663e9
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=6e25b30ca70a2b481bd3232d45b6d854808663e9

Author: Luca Barbieri <luca at luca-barbieri.com>
Date:   Thu Aug 26 18:24:30 2010 +0200

softpipe: respect fragment clamping and turn on ARB_color_buffer_float

Apparently, we were never clamping fragment colors, resulting in
broken OpenGL compliance in presence of blending, even without
floating point targets.

---

 src/gallium/drivers/softpipe/sp_quad_fs.c |   21 +++++++++++++++++++++
 src/gallium/drivers/softpipe/sp_screen.c  |    4 ++++
 2 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/src/gallium/drivers/softpipe/sp_quad_fs.c b/src/gallium/drivers/softpipe/sp_quad_fs.c
index 90f4787..fa6c0ef 100644
--- a/src/gallium/drivers/softpipe/sp_quad_fs.c
+++ b/src/gallium/drivers/softpipe/sp_quad_fs.c
@@ -97,6 +97,24 @@ coverage_quad(struct quad_stage *qs, struct quad_header *quad)
    }
 }
 
+static void
+clamp_quad_color(struct quad_stage *qs, struct quad_header *quad)
+{
+   struct softpipe_context *softpipe = qs->softpipe;
+   uint cbuf;
+
+   /* loop over colorbuffer outputs */
+   for (cbuf = 0; cbuf < softpipe->framebuffer.nr_cbufs; cbuf++) {
+      float (*quadColor)[4] = quad->output.color[cbuf];
+      unsigned i;
+      for (i = 0; i < QUAD_SIZE; i++) {
+         unsigned j;
+         for(j = 0; j < 4; ++j)
+            quadColor[i][j] = CLAMP(quadColor[i][j], 0.0f, 1.0f);
+      }
+   }
+}
+
 
 /**
  * Shade/write an array of quads
@@ -121,6 +139,9 @@ shade_quads(struct quad_stage *qs,
       if (!shade_quad(qs, quads[i]))
          continue; /* quad totally culled/killed */
 
+      if(softpipe->rasterizer->clamp_fragment_color)
+         clamp_quad_color(qs, quads[i] );
+
       if (/*do_coverage*/ 0)
          coverage_quad( qs, quads[i] );
 
diff --git a/src/gallium/drivers/softpipe/sp_screen.c b/src/gallium/drivers/softpipe/sp_screen.c
index 9082a96..1206a5a 100644
--- a/src/gallium/drivers/softpipe/sp_screen.c
+++ b/src/gallium/drivers/softpipe/sp_screen.c
@@ -152,6 +152,10 @@ softpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
 
    case PIPE_CAP_GEOMETRY_SHADER4:
       return 1;
+
+   case PIPE_CAP_UNCLAMPED_VERTEX_COLOR:
+   case PIPE_CAP_UNCLAMPED_FRAGMENT_COLOR:
+      return 1;
    default:
       return 0;
    }