kc3-lang/angle/src/compiler/VersionGLSL.cpp

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• Author : alokp@chromium.org
  Date : 2010-10-13 19:28:25
  Hash : 9ecf3950
  Message : GLSL backend now emits "#version 120" to legally access invariant keyword and gl_PointCoord built-in variable. BUG=35 Review URL: http://codereview.appspot.com/2341043 git-svn-id: https://angleproject.googlecode.com/svn/trunk@448 736b8ea6-26fd-11df-bfd4-992fa37f6226

• src/compiler/VersionGLSL.cpp

• //
  // Copyright (c) 2002-2010 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.
  //
  
  #include "compiler/VersionGLSL.h"
  
  static const int GLSL_VERSION_110 = 110;
  static const int GLSL_VERSION_120 = 120;
  
  // We need to scan for two things:
  // 1. "invariant" keyword: This can occur in both - vertex and fragment shaders
  //    but only at the global scope.
  // 2. "gl_PointCoord" built-in variable: This can only occur in fragment shader
  //    but inside any scope.
  // So we need to scan the entire fragment shader but only the global scope
  // of vertex shader.
  //
  // TODO(alokp): The following two cases of invariant decalaration get lost
  // during parsing - they do not get carried over to the intermediate tree.
  // Handle these cases:
  // 1. When a pragma is used to force all output variables to be invariant:
  //    - #pragma STDGL invariant(all)
  // 2. When a previously decalared or built-in variable is marked invariant:
  //    - invariant gl_Position;
  //    - varying vec3 color; invariant color;
  //
  TVersionGLSL::TVersionGLSL(ShShaderType type)
      : mShaderType(type),
        mVersion(GLSL_VERSION_110)
  {
  }
  
  void TVersionGLSL::visitSymbol(TIntermSymbol* node)
  {
      ASSERT(mShaderType == SH_FRAGMENT_SHADER);
  
      if (node->getSymbol() == "gl_PointCoord")
          updateVersion(GLSL_VERSION_120);
  }
  
  void TVersionGLSL::visitConstantUnion(TIntermConstantUnion*)
  {
      ASSERT(mShaderType == SH_FRAGMENT_SHADER);
  }
  
  bool TVersionGLSL::visitBinary(Visit, TIntermBinary*)
  {
      ASSERT(mShaderType == SH_FRAGMENT_SHADER);
      return true;
  }
  
  bool TVersionGLSL::visitUnary(Visit, TIntermUnary*)
  {
      ASSERT(mShaderType == SH_FRAGMENT_SHADER);
      return true;
  }
  
  bool TVersionGLSL::visitSelection(Visit, TIntermSelection*)
  {
      ASSERT(mShaderType == SH_FRAGMENT_SHADER);
      return true;
  }
  
  bool TVersionGLSL::visitAggregate(Visit, TIntermAggregate* node)
  {
      // We need to scan the entire fragment shader but only the global scope
      // of vertex shader.
      bool visitChildren = mShaderType == SH_FRAGMENT_SHADER ? true : false;
  
      switch (node->getOp()) {
        case EOpSequence:
          // We need to visit sequence children to get to global or inner scope.
          visitChildren = true;
          break;
        case EOpDeclaration: {
          const TIntermSequence& sequence = node->getSequence();
          TQualifier qualifier = sequence.front()->getAsTyped()->getQualifier();
          if ((qualifier == EvqInvariantVaryingIn) ||
              (qualifier == EvqInvariantVaryingOut)) {
              updateVersion(GLSL_VERSION_120);
          }
          break;
        }
        default: break;
      }
  
      return visitChildren;
  }
  
  bool TVersionGLSL::visitLoop(Visit, TIntermLoop*)
  {
      ASSERT(mShaderType == SH_FRAGMENT_SHADER);
      return true;
  }
  
  bool TVersionGLSL::visitBranch(Visit, TIntermBranch*)
  {
      ASSERT(mShaderType == SH_FRAGMENT_SHADER);
      return true;
  }
  
  void TVersionGLSL::updateVersion(int version)
  {
      mVersion = std::max(version, mVersion);
  }