1 files changed, 54 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/compiler/translator/tree_ops/gl/ClampFragDepth.cpp b/gfx/angle/checkout/src/compiler/translator/tree_ops/gl/ClampFragDepth.cpp
new file mode 100644
index 0000000000..309cb14752
--- /dev/null
+++ b/gfx/angle/checkout/src/compiler/translator/tree_ops/gl/ClampFragDepth.cpp
@@ -0,0 +1,54 @@
+//
+// Copyright 2017 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// ClampFragDepth.cpp: Limit the value that is written to gl_FragDepth to the range [0.0, 1.0].
+// The clamping is run at the very end of shader execution, and is only performed if the shader
+// statically accesses gl_FragDepth.
+//
+
+#include "compiler/translator/tree_ops/gl/ClampFragDepth.h"
+
+#include "compiler/translator/ImmutableString.h"
+#include "compiler/translator/SymbolTable.h"
+#include "compiler/translator/tree_util/BuiltIn.h"
+#include "compiler/translator/tree_util/FindSymbolNode.h"
+#include "compiler/translator/tree_util/IntermNode_util.h"
+#include "compiler/translator/tree_util/RunAtTheEndOfShader.h"
+
+namespace sh
+{
+
+bool ClampFragDepth(TCompiler *compiler, TIntermBlock *root, TSymbolTable *symbolTable)
+{
+    // Only clamp gl_FragDepth if it's used in the shader.
+    if (!FindSymbolNode(root, ImmutableString("gl_FragDepth")))
+    {
+        return true;
+    }
+
+    TIntermSymbol *fragDepthNode = new TIntermSymbol(BuiltInVariable::gl_FragDepth());
+
+    TIntermTyped *minFragDepthNode = CreateZeroNode(TType(EbtFloat, EbpHigh, EvqConst));
+
+    TConstantUnion *maxFragDepthConstant = new TConstantUnion();
+    maxFragDepthConstant->setFConst(1.0);
+    TIntermConstantUnion *maxFragDepthNode =
+        new TIntermConstantUnion(maxFragDepthConstant, TType(EbtFloat, EbpHigh, EvqConst));
+
+    // clamp(gl_FragDepth, 0.0, 1.0)
+    TIntermSequence clampArguments;
+    clampArguments.push_back(fragDepthNode->deepCopy());
+    clampArguments.push_back(minFragDepthNode);
+    clampArguments.push_back(maxFragDepthNode);
+    TIntermTyped *clampedFragDepth =
+        CreateBuiltInFunctionCallNode("clamp", &clampArguments, *symbolTable, 100);
+
+    // gl_FragDepth = clamp(gl_FragDepth, 0.0, 1.0)
+    TIntermBinary *assignFragDepth = new TIntermBinary(EOpAssign, fragDepthNode, clampedFragDepth);
+
+    return RunAtTheEndOfShader(compiler, root, assignFragDepth, symbolTable);
+}
+
+}  // namespace sh