Fix decl of gl_FragCoord in GLSL versions <= 1.20.

We we're saying "in" instead of "varying".
Review URL: https://codereview.appspot.com/6779043

git-svn-id: http://skia.googlecode.com/svn/trunk@6104 2bbb7eff-a529-9590-31e7-b0007b416f81

2 files changed, 40 insertions, 1 deletions

diff --git a/src/gpu/gl/GrGLShaderBuilder.cpp b/src/gpu/gl/GrGLShaderBuilder.cpp
index 394b42fa09..a915cfa1ac 100644
--- a/src/gpu/gl/GrGLShaderBuilder.cpp
+++ b/src/gpu/gl/GrGLShaderBuilder.cpp
@@ -289,7 +289,11 @@ const char* GrGLShaderBuilder::fragmentPosition() {
     if (fContext.caps().fragCoordConventionsSupport()) {
         if (!fSetupFragPosition) {
             fFSHeader.append("#extension GL_ARB_fragment_coord_conventions: require\n");
-            fFSHeader.append("layout(origin_upper_left) in vec4 gl_FragCoord;\n");
+            fFSInputs.push_back().set(kVec4f_GrSLType,
+                                      GrGLShaderVar::kIn_TypeModifier,
+                                      "gl_FragCoord",
+                                      GrGLShaderVar::kDefault_Precision,
+                                      GrGLShaderVar::kUpperLeft_Origin);
             fSetupFragPosition = true;
         }
         return "gl_FragCoord";
diff --git a/src/gpu/gl/GrGLShaderVar.h b/src/gpu/gl/GrGLShaderVar.h
index e8f491c511..717cfe0b0e 100644
--- a/src/gpu/gl/GrGLShaderVar.h
+++ b/src/gpu/gl/GrGLShaderVar.h
@@ -45,6 +45,14 @@ public:
     };
 
     /**
+     * See GL_ARB_fragment_coord_conventions.
+     */
+    enum Origin {
+        kDefault_Origin,        // when set to kDefault the origin field is ignored.
+        kUpperLeft_Origin,      // only used to declare vec4 in gl_FragCoord.
+    };
+
+    /**
      * Defaults to a float with no precision specifier
      */
     GrGLShaderVar() {
@@ -52,6 +60,7 @@ public:
         fTypeModifier = kNone_TypeModifier;
         fCount = kNonArray;
         fPrecision = kDefault_Precision;
+        fOrigin = kDefault_Origin;
         fUseUniformFloatArrays = USE_UNIFORM_FLOAT_ARRAYS;
     }
 
@@ -61,6 +70,7 @@ public:
         fTypeModifier = kNone_TypeModifier;
         fCount = arrayCount;
         fPrecision = kDefault_Precision;
+        fOrigin = kDefault_Origin;
         fUseUniformFloatArrays = USE_UNIFORM_FLOAT_ARRAYS;
         fName = name;
     }
@@ -71,6 +81,7 @@ public:
         , fName(var.fName)
         , fCount(var.fCount)
         , fPrecision(var.fPrecision)
+        , fOrigin(fOrigin)
         , fUseUniformFloatArrays(var.fUseUniformFloatArrays) {
         GrAssert(kVoid_GrSLType != var.fType);
     }
@@ -90,6 +101,7 @@ public:
              TypeModifier typeModifier,
              const SkString& name,
              Precision precision = kDefault_Precision,
+             Origin origin = kDefault_Origin,
              bool useUniformFloatArrays = USE_UNIFORM_FLOAT_ARRAYS) {
         GrAssert(kVoid_GrSLType != type);
         fType = type;
@@ -97,6 +109,7 @@ public:
         fName = name;
         fCount = kNonArray;
         fPrecision = precision;
+        fOrigin = origin;
         fUseUniformFloatArrays = useUniformFloatArrays;
     }
 
@@ -107,6 +120,7 @@ public:
              TypeModifier typeModifier,
              const char* name,
              Precision precision = kDefault_Precision,
+             Origin origin = kDefault_Origin,
              bool useUniformFloatArrays = USE_UNIFORM_FLOAT_ARRAYS) {
         GrAssert(kVoid_GrSLType != type);
         fType = type;
@@ -114,6 +128,7 @@ public:
         fName = name;
         fCount = kNonArray;
         fPrecision = precision;
+        fOrigin = origin;
         fUseUniformFloatArrays = useUniformFloatArrays;
     }
 
@@ -125,6 +140,7 @@ public:
              const SkString& name,
              int count,
              Precision precision = kDefault_Precision,
+             Origin origin = kDefault_Origin,
              bool useUniformFloatArrays = USE_UNIFORM_FLOAT_ARRAYS) {
         GrAssert(kVoid_GrSLType != type);
         fType = type;
@@ -132,6 +148,7 @@ public:
         fName = name;
         fCount = count;
         fPrecision = precision;
+        fOrigin = origin;
         fUseUniformFloatArrays = useUniformFloatArrays;
     }
 
@@ -143,6 +160,7 @@ public:
              const char* name,
              int count,
              Precision precision = kDefault_Precision,
+             Origin origin = kDefault_Origin,
              bool useUniformFloatArrays = USE_UNIFORM_FLOAT_ARRAYS) {
         GrAssert(kVoid_GrSLType != type);
         fType = type;
@@ -150,6 +168,7 @@ public:
         fName = name;
         fCount = count;
         fPrecision = precision;
+        fOrigin = origin;
         fUseUniformFloatArrays = useUniformFloatArrays;
     }
 
@@ -221,9 +240,24 @@ public:
     void setPrecision(Precision p) { fPrecision = p; }
 
     /**
+     * Get the origin of the var
+     */
+    Origin getOrigin() const { return fOrigin; }
+
+    /**
+     * Set the origin of the var
+     */
+    void setOrigin(Origin origin) { fOrigin = origin; }
+
+    /**
      * Write a declaration of this variable to out.
      */
     void appendDecl(const GrGLContextInfo& gl, SkString* out) const {
+        if (kUpperLeft_Origin == fOrigin) {
+            // this is the only place where we specify a layout modifier. If we use other layout
+            // modifiers in the future then they should be placed in a list.
+            out->append("layout(origin_upper_left) ");
+        }
         if (this->getTypeModifier() != kNone_TypeModifier) {
            out->append(TypeModifierString(this->getTypeModifier(),
                                           gl.glslGeneration()));
@@ -331,6 +365,7 @@ private:
     SkString        fName;
     int             fCount;
     Precision       fPrecision;
+    Origin          fOrigin;
     /// Work around driver bugs on some hardware that don't correctly
     /// support uniform float []
     bool            fUseUniformFloatArrays;