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//
// 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
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