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

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• Author : Zhenyao Mo
  Date : 2013-09-23 14:57:09
  Hash : ac44cd2b
  Message : Add an option in ANGLE shader translator to initialize gl_Position to vec4(0.0, 0.0, 0.0, 1.0). This is to work around driver bugs where shader compile or program link would fail incorrectly if gl_Position is not set in vertex shader. At the moment at least Linux NVIDIA driver has this bug. ANGLEBUG=472 R=alokp@chromium.org, kbr@chromium.org Review URL: https://codereview.appspot.com/13509043

• src/compiler/InitializeGLPosition.cpp

• //
  // Copyright (c) 2002-2013 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/InitializeGLPosition.h"
  #include "compiler/debug.h"
  
  bool InitializeGLPosition::visitAggregate(Visit visit, TIntermAggregate* node)
  {
      bool visitChildren = !mCodeInserted;
      switch (node->getOp())
      {
        case EOpSequence: break;
        case EOpFunction:
        {
          // Function definition.
          ASSERT(visit == PreVisit);
          if (node->getName() == "main(")
          {
              TIntermSequence &sequence = node->getSequence();
              ASSERT((sequence.size() == 1) || (sequence.size() == 2));
              TIntermAggregate *body = NULL;
              if (sequence.size() == 1)
              {
                  body = new TIntermAggregate(EOpSequence);
                  sequence.push_back(body);
              }
              else
              {
                  body = sequence[1]->getAsAggregate();
              }
              ASSERT(body);
              insertCode(body->getSequence());
              mCodeInserted = true;
          }
          break;
        }
        default: visitChildren = false; break;
      }
      return visitChildren;
  }
  
  void InitializeGLPosition::insertCode(TIntermSequence& sequence)
  {
      TIntermBinary *binary = new TIntermBinary(EOpAssign);
      sequence.insert(sequence.begin(), binary);
  
      TIntermSymbol *left = new TIntermSymbol(
          0, "gl_Position", TType(EbtFloat, EbpUndefined, EvqPosition, 4));
      binary->setLeft(left);
  
      ConstantUnion *u = new ConstantUnion[4];
      for (int ii = 0; ii < 3; ++ii)
          u[ii].setFConst(0.0f);
      u[3].setFConst(1.0f);
      TIntermConstantUnion *right = new TIntermConstantUnion(
          u, TType(EbtFloat, EbpUndefined, EvqConst, 4));
      binary->setRight(right);
  }