i965/gen6+: Add support for noperspective interpolation.

This required the following changes:

- WM setup now makes the appropriate set of barycentric coordinates
  (perspective vs. noperspective) available to the fragment shader,
  based on whether the shader requires perspective interpolation,
  noperspective interpolation, both, or neither.

- The fragment shader backend now uses the appropriate set of
  barycentric coordiantes when interpolating, based on the
  interpolation mode returned by
  ir_variable::determine_interpolation_mode().

- SF setup now uses gl_fragment_program::InterpQualifier to determine
  which attributes are to be flat shaded (as opposed to the old logic,
  which only flat shaded colors).

- CLIP setup now ensures that the clipper outputs non-perspective
  barycentric coordinates when they are needed by the fragment shader.

Fixes the remaining piglit tests of interpolation qualifiers that were
failing:
- interpolation-flat-*-smooth-none
- interpolation-flat-other-flat-none
- interpolation-noperspective-*
- interpolation-smooth-gl_*Color-flat-*

Reviewed-by: Eric Anholt <[email protected]>

1 files changed, 31 insertions, 1 deletions

diff --git a/src/mesa/drivers/dri/i965/gen6_clip_state.c b/src/mesa/drivers/dri/i965/gen6_clip_state.c
index 9b36af47dde..b3bb8aee3ec 100644
--- a/src/mesa/drivers/dri/i965/gen6_clip_state.c
+++ b/src/mesa/drivers/dri/i965/gen6_clip_state.c
@@ -31,6 +31,26 @@
 #include "brw_util.h"
 #include "intel_batchbuffer.h"
 
+/**
+ * Return true if at least one of the inputs used by the given fragment
+ * program has the GLSL "noperspective" interpolation qualifier.
+ */
+bool
+brw_fprog_uses_noperspective(const struct gl_fragment_program *fprog)
+{
+   int attr;
+   for (attr = 0; attr < FRAG_ATTRIB_MAX; ++attr) {
+      /* Ignore unused inputs. */
+      if (!(fprog->Base.InputsRead & BITFIELD64_BIT(attr)))
+         continue;
+
+      if (fprog->InterpQualifier[attr] == INTERP_QUALIFIER_NOPERSPECTIVE)
+         return true;
+   }
+   return false;
+}
+
+
 static void
 upload_clip_state(struct brw_context *brw)
 {
@@ -38,6 +58,14 @@ upload_clip_state(struct brw_context *brw)
    struct gl_context *ctx = &intel->ctx;
    uint32_t depth_clamp = 0;
    uint32_t provoking, userclip;
+   uint32_t nonperspective_barycentric_enable_flag = 0;
+   /* BRW_NEW_FRAGMENT_PROGRAM */
+   const struct gl_fragment_program *fprog = brw->fragment_program;
+
+   if (brw_fprog_uses_noperspective(fprog)) {
+      nonperspective_barycentric_enable_flag =
+         GEN6_CLIP_NON_PERSPECTIVE_BARYCENTRIC_ENABLE;
+   }
 
    if (!ctx->Transform.DepthClamp)
       depth_clamp = GEN6_CLIP_Z_TEST;
@@ -64,6 +92,7 @@ upload_clip_state(struct brw_context *brw)
    OUT_BATCH(GEN6_CLIP_ENABLE |
 	     GEN6_CLIP_API_OGL |
 	     GEN6_CLIP_MODE_NORMAL |
+             nonperspective_barycentric_enable_flag |
 	     GEN6_CLIP_XY_TEST |
 	     userclip << GEN6_USER_CLIP_CLIP_DISTANCES_SHIFT |
 	     depth_clamp |
@@ -77,7 +106,8 @@ upload_clip_state(struct brw_context *brw)
 const struct brw_tracked_state gen6_clip_state = {
    .dirty = {
       .mesa  = _NEW_TRANSFORM | _NEW_LIGHT,
-      .brw   = BRW_NEW_CONTEXT,
+      .brw   = (BRW_NEW_CONTEXT |
+                BRW_NEW_FRAGMENT_PROGRAM),
       .cache = 0
    },
    .emit = upload_clip_state,