st/mesa: do vertex and fragment color clamping in shaders

For ARB_color_buffer_float. Most hardware can't do it and st/mesa is
the perfect place for a fallback.
The exceptions are:
- r500 (vertex clamp only)
- nv50 (both)
- nvc0 (both)
- softpipe (both)

We also have to take into account that r300 can do CLAMPED vertex colors only,
while r600 can do UNCLAMPED vertex colors only. The difference can be expressed
with the two new CAPs.

1 files changed, 11 insertions, 0 deletions

diff --git a/src/mesa/state_tracker/st_context.c b/src/mesa/state_tracker/st_context.c
index dc1d33f1dae..a3fd4dbcb7f 100644
--- a/src/mesa/state_tracker/st_context.c
+++ b/src/mesa/state_tracker/st_context.c
@@ -76,6 +76,17 @@ void st_invalidate_state(struct gl_context * ctx, GLuint new_state)
 {
    struct st_context *st = st_context(ctx);
 
+   /* Replace _NEW_FRAG_CLAMP with ST_NEW_FRAGMENT_PROGRAM for the fallback. */
+   if (st->clamp_frag_color_in_shader && (new_state & _NEW_FRAG_CLAMP)) {
+      new_state &= ~_NEW_FRAG_CLAMP;
+      st->dirty.st |= ST_NEW_FRAGMENT_PROGRAM;
+   }
+
+   /* Update the vertex shader if ctx->Light._ClampVertexColor was changed. */
+   if (st->clamp_vert_color_in_shader && (new_state & _NEW_LIGHT)) {
+      st->dirty.st |= ST_NEW_VERTEX_PROGRAM;
+   }
+
    st->dirty.mesa |= new_state;
    st->dirty.st |= ST_NEW_MESA;