cc: Support texture rect targets for masks

cc/output/shader.cc

Index: cc/output/shader.cc
diff --git a/cc/output/shader.cc b/cc/output/shader.cc
index 8a2521476db9673aea72bd09356700f4214c65df..571438b5b07260eac90c42546c0f9f8d4bdd4ba6 100644
--- a/cc/output/shader.cc
+++ b/cc/output/shader.cc
@@ -1122,13 +1122,13 @@ std::string FragmentShaderRGBATexAlphaMask::GetShaderString(
       // clang-format on
       precision mediump float;
       varying TexCoordPrecision vec2 v_texCoord;
-      uniform SamplerType s_texture;
+      uniform sampler2D s_texture;

[reveman, 2014/10/22 12:40:38]

Is the mask shader always used with a render surface as s_texture input and
that's why this can be hard coded to sampler2D?

[enne (OOO), 2014/10/22 19:20:44]

Yeah, that's exactly it.  Currently, masks only apply to render surfaces and so
they're always sampler2D.

I could generalize this, but I don't really see this changing any time soon.

Is your worry that this assumption about sampler2D isn't correct? Or, is it that
it isn't made clear enough?

[reveman, 2014/10/22 20:36:47]

I just wanted to make sure I understood this change correctly. Pretty sure I'm
the one to blame for the incorrect SamplerType/TextureLookup usage here. Thanks
for fixing it!

It would be nice to explicitly pass sampler and precision parameters to the
FRAGMENT_SHADER macro instead of assuming variables named |precision| and
|sampler| exists. That would allow us to change the name of the "sampler"
parameter above to "mask_sampler" and I think that would be enough to remove any
confusion here. That could be done as a follow up though. Maybe just add a TODO
here for now.

       uniform SamplerType s_mask;
       uniform TexCoordPrecision vec2 maskTexCoordScale;
       uniform TexCoordPrecision vec2 maskTexCoordOffset;
       uniform float alpha;
       void main() {
-        vec4 texColor = TextureLookup(s_texture, v_texCoord);
+        vec4 texColor = texture2D(s_texture, v_texCoord);
         TexCoordPrecision vec2 maskTexCoord =
             vec2(maskTexCoordOffset.x + v_texCoord.x * maskTexCoordScale.x,
                  maskTexCoordOffset.y + v_texCoord.y * maskTexCoordScale.y);
@@ -1176,7 +1176,7 @@ std::string FragmentShaderRGBATexAlphaMaskAA::GetShaderString(
   return FRAGMENT_SHADER(
       // clang-format on
       precision mediump float;
-      uniform SamplerType s_texture;
+      uniform sampler2D s_texture;
       uniform SamplerType s_mask;
       uniform TexCoordPrecision vec2 maskTexCoordScale;
       uniform TexCoordPrecision vec2 maskTexCoordOffset;
@@ -1185,7 +1185,7 @@ std::string FragmentShaderRGBATexAlphaMaskAA::GetShaderString(
       varying TexCoordPrecision vec4 edge_dist[2];  // 8 edge distances.
 
       void main() {
-        vec4 texColor = TextureLookup(s_texture, v_texCoord);
+        vec4 texColor = texture2D(s_texture, v_texCoord);
         TexCoordPrecision vec2 maskTexCoord =
             vec2(maskTexCoordOffset.x + v_texCoord.x * maskTexCoordScale.x,
                  maskTexCoordOffset.y + v_texCoord.y * maskTexCoordScale.y);
@@ -1247,7 +1247,7 @@ std::string FragmentShaderRGBATexAlphaMaskColorMatrixAA::GetShaderString(
   return FRAGMENT_SHADER(
       // clang-format on
       precision mediump float;
-      uniform SamplerType s_texture;
+      uniform sampler2D s_texture;
       uniform SamplerType s_mask;
       uniform vec2 maskTexCoordScale;
       uniform vec2 maskTexCoordOffset;
@@ -1258,7 +1258,7 @@ std::string FragmentShaderRGBATexAlphaMaskColorMatrixAA::GetShaderString(
       varying TexCoordPrecision vec4 edge_dist[2];  // 8 edge distances.
 
       void main() {
-        vec4 texColor = TextureLookup(s_texture, v_texCoord);
+        vec4 texColor = texture2D(s_texture, v_texCoord);
         float nonZeroAlpha = max(texColor.a, 0.00001);
         texColor = vec4(texColor.rgb / nonZeroAlpha, nonZeroAlpha);
         texColor = colorMatrix * texColor + colorOffset;
@@ -1382,7 +1382,7 @@ std::string FragmentShaderRGBATexAlphaMaskColorMatrix::GetShaderString(
       // clang-format on
       precision mediump float;
       varying TexCoordPrecision vec2 v_texCoord;
-      uniform SamplerType s_texture;
+      uniform sampler2D s_texture;
       uniform SamplerType s_mask;
       uniform vec2 maskTexCoordScale;
       uniform vec2 maskTexCoordOffset;
@@ -1390,7 +1390,7 @@ std::string FragmentShaderRGBATexAlphaMaskColorMatrix::GetShaderString(
       uniform vec4 colorOffset;
       uniform float alpha;
       void main() {
-        vec4 texColor = TextureLookup(s_texture, v_texCoord);
+        vec4 texColor = texture2D(s_texture, v_texCoord);
         float nonZeroAlpha = max(texColor.a, 0.00001);
         texColor = vec4(texColor.rgb / nonZeroAlpha, nonZeroAlpha);
         texColor = colorMatrix * texColor + colorOffset;