Flip the switch to turn on GrCustomStage implementation of gradients;
remove old implementation, including enums & state on various structs.

http://codereview.appspot.com/6245078/



git-svn-id: http://skia.googlecode.com/svn/trunk@4129 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/effects/GrGradientEffects.cpp b/src/gpu/effects/GrGradientEffects.cpp
index b1bf82f..000e0e5 100644
--- a/src/gpu/effects/GrGradientEffects.cpp
+++ b/src/gpu/effects/GrGradientEffects.cpp
@@ -212,7 +212,7 @@
 
     // If we aren't degenerate, emit some extra code, and accept a slightly
     // more complex coord.
-    if (fIsDegenerate) {
+    if (!fIsDegenerate) {
 
         // ac4 = 4.0 * params[0] * c
         code->appendf("\tfloat %s = %s * 4.0 * %s;\n",
diff --git a/src/gpu/effects/GrGradientEffects.h b/src/gpu/effects/GrGradientEffects.h
index 8d67c25..9bcf9dd 100644
--- a/src/gpu/effects/GrGradientEffects.h
+++ b/src/gpu/effects/GrGradientEffects.h
@@ -12,6 +12,29 @@
 #include "GrTypes.h"
 #include "GrScalar.h"
 
+/*
+ * The intepretation of the texture matrix depends on the sample mode. The
+ * texture matrix is applied both when the texture coordinates are explicit
+ * and  when vertex positions are used as texture  coordinates. In the latter
+ * case the texture matrix is applied to the pre-view-matrix position 
+ * values.
+ *
+ * Normal SampleMode
+ *  The post-matrix texture coordinates are in normalize space with (0,0) at
+ *  the top-left and (1,1) at the bottom right.
+ * RadialGradient
+ *  The matrix specifies the radial gradient parameters.
+ *  (0,0) in the post-matrix space is center of the radial gradient.
+ * Radial2Gradient
+ *   Matrix transforms to space where first circle is centered at the
+ *   origin. The second circle will be centered (x, 0) where x may be 
+ *   0 and is provided by setRadial2Params. The post-matrix space is 
+ *   normalized such that 1 is the second radius - first radius.
+ * SweepGradient
+ *  The angle from the origin of texture coordinates in post-matrix space
+ *  determines the gradient value.
+ */
+
 class GrGLRadialGradient;
 
 class GrRadialGradient : public GrCustomStage {