Update Alligned Rect Shader to match geometry version

src/gpu/GrAARectRenderer.cpp

Index: src/gpu/GrAARectRenderer.cpp
diff --git a/src/gpu/GrAARectRenderer.cpp b/src/gpu/GrAARectRenderer.cpp
index f28d91456308143206a0f77310df60cd8a24f263..4a0be98661053715069c41f0e01d072cb5df4491 100644
--- a/src/gpu/GrAARectRenderer.cpp
+++ b/src/gpu/GrAARectRenderer.cpp
@@ -61,21 +61,22 @@ public:
 

[robertphillips, 2013/06/13 17:45:52]

This comment is now orphaned

[egdaniel, 2013/06/13 19:17:46]

What do you mean by orphaned? Both the TODO and the comment below it are still
valid.

On 2013/06/13 17:45:52, robertphillips wrote:

[robertphillips, 2013/06/13 19:55:24]

It isn't as relevant in this iteration but in an earlier version the computation
of the scales was further away from the comments.

             // TODO: compute these scale factors in the VS
             // These scale factors adjust the coverage for < 1 pixel wide/high rects
-            builder->fsCodeAppendf("\tfloat wScale = max(1.0, 2.0/(0.5+%s.z));\n",
-                                   fsRectName);
-            builder->fsCodeAppendf("\tfloat hScale = max(1.0, 2.0/(0.5+%s.w));\n",
-                                   fsRectName);
+            builder->fsCodeAppendf("\tfloat insetW = min(1.0, %s.z) - 0.5;\n", fsRectName);
+            builder->fsCodeAppendf("\tfloat insetH = min(1.0, %s.w) - 0.5;\n", fsRectName);
+            builder->fsCodeAppend("\tfloat outset = 0.5;\n");

[bsalomon, 2013/06/13 14:27:51]

static const?

I'm not sure, but I think windows may (dumbly) give you a double to float
truncation warning if you don't make this 0.5f.

[egdaniel, 2013/06/13 14:52:18]

On 2013/06/13 14:27:51, bsalomon wrote:
I will make it const, but is there a static in glsl? The variable is mostly
there right now as a place holder for if/when I try different outset widths. Or
do you mean define it within the c++ class?

[bsalomon, 2013/06/13 14:55:45]

I'm a moron... I was reading this as c code. ignore both comments.

+            builder->fsCodeAppend("\tfloat spanW = insetW + outset;\n");
+            builder->fsCodeAppend("\tfloat spanH = insetH + outset;\n");
+            builder->fsCodeAppend("\tfloat scaleW = min(1.0, 2*insetW/(spanW));\n");

[bsalomon, 2013/06/13 14:27:51]

need the parens in the divisor?

+            builder->fsCodeAppend("\tfloat scaleH = min(1.0, 2*insetH/(spanH));\n");
 
             // Compute the coverage for the rect's width
-            builder->fsCodeAppendf("\tfloat coverage = clamp(wScale*(%s.z-abs(%s.x)), 0.0, 1.0);\n",
-                                   fsRectName,
-                                   fsRectName);
-
+            builder->fsCodeAppendf(
+                "\tfloat coverage = scaleW*clamp((%s.z-abs(%s.x))/spanW, 0.0, 1.0);\n", fsRectName, 
+                fsRectName);
             // Compute the coverage for the rect's height and merge with the width
             builder->fsCodeAppendf(
-                    "\tcoverage = min(coverage, clamp(hScale*(%s.w-abs(%s.y)), 0.0, 1.0));\n",
-                    fsRectName,
-                    fsRectName);
+                "\tcoverage = coverage*scaleH*clamp((%s.w-abs(%s.y))/spanH, 0.0, 1.0);\n",fsRectName,
+                fsRectName);
 
             SkString modulate;
             GrGLSLModulatef<4>(&modulate, inputColor, "coverage");