mesa: allow variable indexing into the predefined uniform variable arrays

This allows code such as "vec4 a = gl_LightSource[i].ambient;" to work.

When a built-in uniform array is indexed with a variable index we need to
"unroll" the whole array into the parameter list (aka constant buffer) because
we don't know which elements may be accessed at compile-time.  In the case of
the gl_LightSource array of size [8], we emit 64 state references into the
parameter array (8 elements times 8 vec4s per gl_LightSourceParameters
struct).

Previously, we only allowed constant-indexed references to uniform arrays
(such as gl_LightSource[2].position) which resulted in a single state reference
being added to the parameter array, not 64.  We still optimize this case.

Users should be aware that using "gl_LightSource[i].ambient" in their shaders
is a bit expensive since state validation will involve updating all 64
light source entries in the parameter list.

1 files changed, 9 insertions, 3 deletions

diff --git a/src/mesa/shader/slang/library/slang_common_builtin.gc b/src/mesa/shader/slang/library/slang_common_builtin.gc
index a051c53eea..3e03b101b8 100644
--- a/src/mesa/shader/slang/library/slang_common_builtin.gc
+++ b/src/mesa/shader/slang/library/slang_common_builtin.gc
@@ -1,8 +1,9 @@
 /*
  * Mesa 3-D graphics library
- * Version:  6.5
+ * Version:  7.3
  *
  * Copyright (C) 2006  Brian Paul   All Rights Reserved.
+ * Copyright (C) 2008  VMware, Inc.  All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -98,6 +99,9 @@ struct gl_MaterialParameters {
 uniform gl_MaterialParameters gl_FrontMaterial;
 uniform gl_MaterialParameters gl_BackMaterial;
 
+/* NOTE: the order of these fields is significant!
+ * See the definition of the lighting state vars such as STATE_SPOT_DIRECTION.
+ */
 struct gl_LightSourceParameters {
     vec4 ambient;
     vec4 diffuse;
@@ -105,12 +109,14 @@ struct gl_LightSourceParameters {
     vec4 position;
     vec4 halfVector;
     vec3 spotDirection;
-    float spotExponent;
-    float spotCutoff;
     float spotCosCutoff;
+
     float constantAttenuation;
     float linearAttenuation;
     float quadraticAttenuation;
+    float spotExponent;
+
+    float spotCutoff;
 };
 
 uniform gl_LightSourceParameters gl_LightSource[gl_MaxLights];