Automatically handle converting gl_FragCoord to Skia's y-down device coords.

NOTE: THIS WILL LIKELY REQUIRE GM REBASELINING.

R=robertphillips@google.com,senorblanco@chromium.org
Review URL: https://codereview.appspot.com/6744061

git-svn-id: http://skia.googlecode.com/svn/trunk@6030 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/gl/GrGLProgram.cpp b/src/gpu/gl/GrGLProgram.cpp
index 066da35..8824114 100644
--- a/src/gpu/gl/GrGLProgram.cpp
+++ b/src/gpu/gl/GrGLProgram.cpp
@@ -77,6 +77,7 @@
     fViewportSize.set(-1, -1);
     fColor = GrColor_ILLEGAL;
     fColorFilterColor = GrColor_ILLEGAL;
+    fRTHeight = -1;
 
     for (int s = 0; s < GrDrawState::kNumStages; ++s) {
         fProgramStage[s] = NULL;
@@ -234,56 +235,57 @@
 }
 
 bool GrGLProgram::genEdgeCoverage(SkString* coverageVar,
-                                  GrGLShaderBuilder* segments) const {
+                                  GrGLShaderBuilder* builder) const {
     if (fDesc.fVertexLayout & GrDrawTarget::kEdge_VertexLayoutBit) {
         const char *vsName, *fsName;
-        segments->addVarying(kVec4f_GrSLType, "Edge", &vsName, &fsName);
-        segments->fVSAttrs.push_back().set(kVec4f_GrSLType,
-            GrGLShaderVar::kAttribute_TypeModifier, EDGE_ATTR_NAME);
-        segments->fVSCode.appendf("\t%s = " EDGE_ATTR_NAME ";\n", vsName);
+        builder->addVarying(kVec4f_GrSLType, "Edge", &vsName, &fsName);
+        builder->fVSAttrs.push_back().set(kVec4f_GrSLType,
+                                          GrGLShaderVar::kAttribute_TypeModifier,
+                                          EDGE_ATTR_NAME);
+        builder->fVSCode.appendf("\t%s = " EDGE_ATTR_NAME ";\n", vsName);
         switch (fDesc.fVertexEdgeType) {
         case GrDrawState::kHairLine_EdgeType:
-            segments->fFSCode.appendf("\tfloat edgeAlpha = abs(dot(vec3(gl_FragCoord.xy,1), %s.xyz));\n", fsName);
-            segments->fFSCode.append("\tedgeAlpha = max(1.0 - edgeAlpha, 0.0);\n");
+            builder->fFSCode.appendf("\tfloat edgeAlpha = abs(dot(vec3(%s.xy,1), %s.xyz));\n", builder->fragmentPosition(), fsName);
+            builder->fFSCode.append("\tedgeAlpha = max(1.0 - edgeAlpha, 0.0);\n");
             break;
         case GrDrawState::kQuad_EdgeType:
-            segments->fFSCode.append("\tfloat edgeAlpha;\n");
+            builder->fFSCode.append("\tfloat edgeAlpha;\n");
             // keep the derivative instructions outside the conditional
-            segments->fFSCode.appendf("\tvec2 duvdx = dFdx(%s.xy);\n", fsName);
-            segments->fFSCode.appendf("\tvec2 duvdy = dFdy(%s.xy);\n", fsName);
-            segments->fFSCode.appendf("\tif (%s.z > 0.0 && %s.w > 0.0) {\n", fsName, fsName);
+            builder->fFSCode.appendf("\tvec2 duvdx = dFdx(%s.xy);\n", fsName);
+            builder->fFSCode.appendf("\tvec2 duvdy = dFdy(%s.xy);\n", fsName);
+            builder->fFSCode.appendf("\tif (%s.z > 0.0 && %s.w > 0.0) {\n", fsName, fsName);
             // today we know z and w are in device space. We could use derivatives
-            segments->fFSCode.appendf("\t\tedgeAlpha = min(min(%s.z, %s.w) + 0.5, 1.0);\n", fsName, fsName);
-            segments->fFSCode.append ("\t} else {\n");
-            segments->fFSCode.appendf("\t\tvec2 gF = vec2(2.0*%s.x*duvdx.x - duvdx.y,\n"
-                                      "\t\t               2.0*%s.x*duvdy.x - duvdy.y);\n",
-                                      fsName, fsName);
-            segments->fFSCode.appendf("\t\tedgeAlpha = (%s.x*%s.x - %s.y);\n", fsName, fsName, fsName);
-            segments->fFSCode.append("\t\tedgeAlpha = clamp(0.5 - edgeAlpha / length(gF), 0.0, 1.0);\n"
-                                      "\t}\n");
+            builder->fFSCode.appendf("\t\tedgeAlpha = min(min(%s.z, %s.w) + 0.5, 1.0);\n", fsName, fsName);
+            builder->fFSCode.append ("\t} else {\n");
+            builder->fFSCode.appendf("\t\tvec2 gF = vec2(2.0*%s.x*duvdx.x - duvdx.y,\n"
+                                     "\t\t               2.0*%s.x*duvdy.x - duvdy.y);\n",
+                                     fsName, fsName);
+            builder->fFSCode.appendf("\t\tedgeAlpha = (%s.x*%s.x - %s.y);\n", fsName, fsName, fsName);
+            builder->fFSCode.append("\t\tedgeAlpha = clamp(0.5 - edgeAlpha / length(gF), 0.0, 1.0);\n"
+                                    "\t}\n");
             if (kES2_GrGLBinding == fContextInfo.binding()) {
-                segments->fHeader.printf("#extension GL_OES_standard_derivatives: enable\n");
+                builder->fHeader.printf("#extension GL_OES_standard_derivatives: enable\n");
             }
             break;
         case GrDrawState::kHairQuad_EdgeType:
-            segments->fFSCode.appendf("\tvec2 duvdx = dFdx(%s.xy);\n", fsName);
-            segments->fFSCode.appendf("\tvec2 duvdy = dFdy(%s.xy);\n", fsName);
-            segments->fFSCode.appendf("\tvec2 gF = vec2(2.0*%s.x*duvdx.x - duvdx.y,\n"
-                                      "\t               2.0*%s.x*duvdy.x - duvdy.y);\n",
-                                      fsName, fsName);
-            segments->fFSCode.appendf("\tfloat edgeAlpha = (%s.x*%s.x - %s.y);\n", fsName, fsName, fsName);
-            segments->fFSCode.append("\tedgeAlpha = sqrt(edgeAlpha*edgeAlpha / dot(gF, gF));\n");
-            segments->fFSCode.append("\tedgeAlpha = max(1.0 - edgeAlpha, 0.0);\n");
+            builder->fFSCode.appendf("\tvec2 duvdx = dFdx(%s.xy);\n", fsName);
+            builder->fFSCode.appendf("\tvec2 duvdy = dFdy(%s.xy);\n", fsName);
+            builder->fFSCode.appendf("\tvec2 gF = vec2(2.0*%s.x*duvdx.x - duvdx.y,\n"
+                                     "\t               2.0*%s.x*duvdy.x - duvdy.y);\n",
+                                     fsName, fsName);
+            builder->fFSCode.appendf("\tfloat edgeAlpha = (%s.x*%s.x - %s.y);\n", fsName, fsName, fsName);
+            builder->fFSCode.append("\tedgeAlpha = sqrt(edgeAlpha*edgeAlpha / dot(gF, gF));\n");
+            builder->fFSCode.append("\tedgeAlpha = max(1.0 - edgeAlpha, 0.0);\n");
             if (kES2_GrGLBinding == fContextInfo.binding()) {
-                segments->fHeader.printf("#extension GL_OES_standard_derivatives: enable\n");
+                builder->fHeader.printf("#extension GL_OES_standard_derivatives: enable\n");
             }
             break;
         case GrDrawState::kCircle_EdgeType:
-            segments->fFSCode.append("\tfloat edgeAlpha;\n");
-            segments->fFSCode.appendf("\tfloat d = distance(gl_FragCoord.xy, %s.xy);\n", fsName);
-            segments->fFSCode.appendf("\tfloat outerAlpha = smoothstep(d - 0.5, d + 0.5, %s.z);\n", fsName);
-            segments->fFSCode.appendf("\tfloat innerAlpha = %s.w == 0.0 ? 1.0 : smoothstep(%s.w - 0.5, %s.w + 0.5, d);\n", fsName, fsName, fsName);
-            segments->fFSCode.append("\tedgeAlpha = outerAlpha * innerAlpha;\n");
+            builder->fFSCode.append("\tfloat edgeAlpha;\n");
+            builder->fFSCode.appendf("\tfloat d = distance(%s.xy, %s.xy);\n", builder->fragmentPosition(), fsName);
+            builder->fFSCode.appendf("\tfloat outerAlpha = smoothstep(d - 0.5, d + 0.5, %s.z);\n", fsName);
+            builder->fFSCode.appendf("\tfloat innerAlpha = %s.w == 0.0 ? 1.0 : smoothstep(%s.w - 0.5, %s.w + 0.5, d);\n", fsName, fsName, fsName);
+            builder->fFSCode.append("\tedgeAlpha = outerAlpha * innerAlpha;\n");
             break;
         default:
             GrCrash("Unknown Edge Type!");
@@ -807,6 +809,7 @@
 
     builder.finished(fProgramID);
     this->initSamplerUniforms();
+    fUniforms.fRTHeight = builder.getRTHeightUniform();
 
     return true;
 }
@@ -964,7 +967,13 @@
     return glStage;
 }
 
-void GrGLProgram::setData(const GrDrawState& drawState) const {
+void GrGLProgram::setData(const GrDrawState& drawState) {
+    int rtHeight = drawState.getRenderTarget()->height();
+    if (GrGLUniformManager::kInvalidUniformHandle != fUniforms.fRTHeight &&
+        rtHeight != fRTHeight) {
+        fUniformManager.set1f(fUniforms.fRTHeight, GrIntToScalar(rtHeight));
+        fRTHeight = rtHeight;
+    }
     for (int s = 0; s < GrDrawState::kNumStages; ++s) {
         if (NULL != fProgramStage[s]) {
             const GrSamplerState& sampler = drawState.getSampler(s);