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      1 //
      2 // Copyright (c) 2013-2014 The ANGLE Project Authors. All rights reserved.
      3 // Use of this source code is governed by a BSD-style license that can be
      4 // found in the LICENSE file.
      5 //
      6 // blocklayout.h:
      7 //   Methods and classes related to uniform layout and packing in GLSL and HLSL.
      8 //
      9 
     10 #ifndef COMMON_BLOCKLAYOUT_H_
     11 #define COMMON_BLOCKLAYOUT_H_
     12 
     13 #include <vector>
     14 #include <GLES3/gl3.h>
     15 #include <GLES2/gl2.h>
     16 #include <GLSLANG/ShaderLang.h>
     17 #include <cstddef>
     18 
     19 namespace gl
     20 {
     21 
     22 struct ShaderVariable;
     23 struct InterfaceBlockField;
     24 struct BlockMemberInfo;
     25 struct Uniform;
     26 struct Varying;
     27 
     28 class BlockLayoutEncoder
     29 {
     30   public:
     31     BlockLayoutEncoder(std::vector<BlockMemberInfo> *blockInfoOut);
     32 
     33     void encodeInterfaceBlockFields(const std::vector<InterfaceBlockField> &fields);
     34     void encodeInterfaceBlockField(const InterfaceBlockField &field);
     35     void encodeType(GLenum type, unsigned int arraySize, bool isRowMajorMatrix);
     36     size_t getBlockSize() const { return mCurrentOffset * BytesPerComponent; }
     37 
     38     static const size_t BytesPerComponent = 4u;
     39     static const unsigned int ComponentsPerRegister = 4u;
     40 
     41   protected:
     42     size_t mCurrentOffset;
     43 
     44     void nextRegister();
     45 
     46     virtual void enterAggregateType() = 0;
     47     virtual void exitAggregateType() = 0;
     48     virtual void getBlockLayoutInfo(GLenum type, unsigned int arraySize, bool isRowMajorMatrix, int *arrayStrideOut, int *matrixStrideOut) = 0;
     49     virtual void advanceOffset(GLenum type, unsigned int arraySize, bool isRowMajorMatrix, int arrayStride, int matrixStride) = 0;
     50 
     51   private:
     52     std::vector<BlockMemberInfo> *mBlockInfoOut;
     53 };
     54 
     55 // Block layout according to the std140 block layout
     56 // See "Standard Uniform Block Layout" in Section 2.11.6 of the OpenGL ES 3.0 specification
     57 
     58 class Std140BlockEncoder : public BlockLayoutEncoder
     59 {
     60   public:
     61     Std140BlockEncoder(std::vector<BlockMemberInfo> *blockInfoOut);
     62 
     63   protected:
     64     virtual void enterAggregateType();
     65     virtual void exitAggregateType();
     66     virtual void getBlockLayoutInfo(GLenum type, unsigned int arraySize, bool isRowMajorMatrix, int *arrayStrideOut, int *matrixStrideOut);
     67     virtual void advanceOffset(GLenum type, unsigned int arraySize, bool isRowMajorMatrix, int arrayStride, int matrixStride);
     68 };
     69 
     70 // Block layout packed according to the D3D9 or default D3D10+ register packing rules
     71 // See http://msdn.microsoft.com/en-us/library/windows/desktop/bb509632(v=vs.85).aspx
     72 // The strategy should be ENCODE_LOOSE for D3D9 constnat blocks, and ENCODE_PACKED
     73 // for everything else (D3D10+ constant blocks and all attributes/varyings).
     74 
     75 class HLSLBlockEncoder : public BlockLayoutEncoder
     76 {
     77   public:
     78     enum HLSLBlockEncoderStrategy
     79     {
     80         ENCODE_PACKED,
     81         ENCODE_LOOSE
     82     };
     83 
     84     HLSLBlockEncoder(std::vector<BlockMemberInfo> *blockInfoOut,
     85                      HLSLBlockEncoderStrategy strategy);
     86 
     87     virtual void enterAggregateType();
     88     virtual void exitAggregateType();
     89     void skipRegisters(unsigned int numRegisters);
     90 
     91     bool isPacked() const { return mEncoderStrategy == ENCODE_PACKED; }
     92 
     93   protected:
     94     virtual void getBlockLayoutInfo(GLenum type, unsigned int arraySize, bool isRowMajorMatrix, int *arrayStrideOut, int *matrixStrideOut);
     95     virtual void advanceOffset(GLenum type, unsigned int arraySize, bool isRowMajorMatrix, int arrayStride, int matrixStride);
     96 
     97     HLSLBlockEncoderStrategy mEncoderStrategy;
     98 };
     99 
    100 // This method assigns values to the variable's "registerIndex" and "elementIndex" fields.
    101 // "elementIndex" is only used for structures.
    102 void HLSLVariableGetRegisterInfo(unsigned int baseRegisterIndex, Uniform *variable, ShShaderOutput outputType);
    103 
    104 // This method returns the number of used registers for a ShaderVariable. It is dependent on the HLSLBlockEncoder
    105 // class to count the number of used registers in a struct (which are individually packed according to the same rules).
    106 unsigned int HLSLVariableRegisterCount(const Varying &variable);
    107 unsigned int HLSLVariableRegisterCount(const Uniform &variable, ShShaderOutput outputType);
    108 
    109 }
    110 
    111 #endif // COMMON_BLOCKLAYOUT_H_
    112