fix for FB fetch on nexus 10 ES3.0

BUG=skia:3304

Review URL: https://codereview.chromium.org/807143006

3 files changed, 11 insertions, 4 deletions

diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index b729820ca5..376bfd432a 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -50,6 +50,7 @@ void GrGLCaps::reset() {
     fFullClearIsFree = false;
     fDropsTileOnZeroDivide = false;
     fFBFetchSupport = false;
+    fFBFetchNeedsCustomOutput = false;
     fFBFetchColorName = NULL;
     fFBFetchExtensionString = NULL;
 
@@ -93,6 +94,7 @@ GrGLCaps& GrGLCaps::operator= (const GrGLCaps& caps) {
     fFullClearIsFree = caps.fFullClearIsFree;
     fDropsTileOnZeroDivide = caps.fDropsTileOnZeroDivide;
     fFBFetchSupport = caps.fFBFetchSupport;
+    fFBFetchNeedsCustomOutput = caps.fFBFetchNeedsCustomOutput;
     fFBFetchColorName = caps.fFBFetchColorName;
     fFBFetchExtensionString = caps.fFBFetchExtensionString;
 
@@ -250,16 +252,19 @@ bool GrGLCaps::init(const GrGLContextInfo& ctxInfo, const GrGLInterface* gli) {
 
     if (kGLES_GrGLStandard == standard) {
         if (ctxInfo.hasExtension("GL_EXT_shader_framebuffer_fetch")) {
+            fFBFetchNeedsCustomOutput = (version >= GR_GL_VER(3, 0));
             fFBFetchSupport = true;
             fFBFetchColorName = "gl_LastFragData[0]";
             fFBFetchExtensionString = "GL_EXT_shader_framebuffer_fetch";
         } else if (ctxInfo.hasExtension("GL_NV_shader_framebuffer_fetch")) {
+            // Actually, we haven't seen an ES3.0 device with this extension yet, so we don't know
+            fFBFetchNeedsCustomOutput = false;
             fFBFetchSupport = true;
             fFBFetchColorName = "gl_LastFragData[0]";
             fFBFetchExtensionString = "GL_NV_shader_framebuffer_fetch";
         } else if (ctxInfo.hasExtension("GL_ARM_shader_framebuffer_fetch")) {
             // The arm extension also requires an additional flag which we will set onResetContext
-            // This is all temporary.
+            fFBFetchNeedsCustomOutput = false;
             fFBFetchSupport = true;
             fFBFetchColorName = "gl_LastFragColorARM";
             fFBFetchExtensionString = "GL_ARM_shader_framebuffer_fetch";
diff --git a/src/gpu/gl/GrGLCaps.h b/src/gpu/gl/GrGLCaps.h
index 7ccb1d9f5d..77baf38a96 100644
--- a/src/gpu/gl/GrGLCaps.h
+++ b/src/gpu/gl/GrGLCaps.h
@@ -172,6 +172,8 @@ public:
      */
     bool fbFetchSupport() const { return fFBFetchSupport; }
 
+    bool fbFetchNeedsCustomOutput() const { return fFBFetchNeedsCustomOutput; }
+
     const char* fbFetchColorName() const { return fFBFetchColorName; }
 
     const char* fbFetchExtensionString() const { return fFBFetchExtensionString; }
@@ -372,8 +374,8 @@ private:
     bool fIsCoreProfile : 1;
     bool fFullClearIsFree : 1;
     bool fDropsTileOnZeroDivide : 1;
-    // TODO(joshualitt) encapsulate the FB Fetch logic in a feature object
     bool fFBFetchSupport : 1;
+    bool fFBFetchNeedsCustomOutput : 1;
 
     const char* fFBFetchColorName;
     const char* fFBFetchExtensionString;
diff --git a/src/gpu/gl/builders/GrGLFragmentShaderBuilder.cpp b/src/gpu/gl/builders/GrGLFragmentShaderBuilder.cpp
index b59df57512..46433f01c2 100644
--- a/src/gpu/gl/builders/GrGLFragmentShaderBuilder.cpp
+++ b/src/gpu/gl/builders/GrGLFragmentShaderBuilder.cpp
@@ -171,9 +171,9 @@ const char* GrGLFragmentShaderBuilder::dstColor() {
         this->addFeature(1 << (GrGLFragmentShaderBuilder::kLastGLSLPrivateFeature + 1),
                          gpu->glCaps().fbFetchExtensionString());
 
-        // On ES 3.0 we have to declare this, and use the custom color output name
+        // Some versions of this extension string require declaring custom color output on ES 3.0+
         const char* fbFetchColorName = gpu->glCaps().fbFetchColorName();
-        if (gpu->glslGeneration() >= k330_GrGLSLGeneration) {
+        if (gpu->glCaps().fbFetchNeedsCustomOutput()) {
             this->enableCustomOutput();
             fOutputs[fCustomColorOutputIndex].setTypeModifier(GrShaderVar::kInOut_TypeModifier);
             fbFetchColorName = declared_color_output_name();