Move external texture extension logic into SkSL

Automatically enable the extension if any external samplers are used.

Bug: skia:7713
Change-Id: I1de2faddd7c8eda864873941b90d7a4c4606497a
Reviewed-on: https://skia-review.googlesource.com/121797
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

3 files changed, 13 insertions, 0 deletions

diff --git a/src/sksl/SkSLGLSLCodeGenerator.cpp b/src/sksl/SkSLGLSLCodeGenerator.cpp
index 0ee0afa6a6..bcf45ba7be 100644
--- a/src/sksl/SkSLGLSLCodeGenerator.cpp
+++ b/src/sksl/SkSLGLSLCodeGenerator.cpp
@@ -1083,6 +1083,14 @@ void GLSLCodeGenerator::writeVarDeclarations(const VarDeclarations& decl, bool g
             }
             fFoundImageDecl = true;
         }
+        if (!fFoundExternalSamplerDecl && var.fVar->fType == *fContext.fSamplerExternalOES_Type) {
+            if (fProgram.fSettings.fCaps->externalTextureExtensionString()) {
+                fHeader.writeText("#extension ");
+                fHeader.writeText(fProgram.fSettings.fCaps->externalTextureExtensionString());
+                fHeader.writeText(" : require\n");
+            }
+            fFoundExternalSamplerDecl = true;
+        }
     }
     if (wroteType) {
         this->write(";");
diff --git a/src/sksl/SkSLGLSLCodeGenerator.h b/src/sksl/SkSLGLSLCodeGenerator.h
index 2b308e3702..362ae7ca18 100644
--- a/src/sksl/SkSLGLSLCodeGenerator.h
+++ b/src/sksl/SkSLGLSLCodeGenerator.h
@@ -209,6 +209,7 @@ protected:
     // true if we have run into usages of dFdx / dFdy
     bool fFoundDerivatives = false;
     bool fFoundImageDecl = false;
+    bool fFoundExternalSamplerDecl = false;
     bool fFoundGSInvocations = false;
     bool fSetupFragPositionGlobal = false;
     bool fSetupFragPositionLocal = false;
diff --git a/src/sksl/SkSLUtil.h b/src/sksl/SkSLUtil.h
index 78a80736b8..dc87246605 100644
--- a/src/sksl/SkSLUtil.h
+++ b/src/sksl/SkSLUtil.h
@@ -151,6 +151,10 @@ public:
         return nullptr;
     }
 
+    const char* externalTextureExtensionString() const {
+        return nullptr;
+    }
+
     const char* versionDeclString() const {
         return "";
     }