kc3-lang/angle/src/libANGLE/VertexAttribute.cpp

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• Hash : 553590a5
  Author :
  Date : 2017-07-31T16:40:39
  

  Modify attribute divisor for multiview instanced rendering
  
  If the ANGLE_multiview extension is used in a program, the number
  of geometry instances is the number of instances passed to
  glDraw*Instanced times the number of views in the program. The attribute
  divisor has to be multiplied by the number of views so that the correct
  attributes are gathered in the input assembly stage.
  
  BUG=angleproject:2062
  TEST=angle_end2end_tests
  
  Change-Id: I960d6313c02e3eb83f7a07e72b9bcac072c736f4
  Reviewed-on: https://chromium-review.googlesource.com/593953
  Commit-Queue: Martin Radev <mradev@nvidia.com>
  Reviewed-by: Geoff Lang <geofflang@chromium.org>
  

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• src/libANGLE/VertexAttribute.cpp

• //
  // Copyright 2014 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.
  //
  // Implementation of the state classes for mananging GLES 3.1 Vertex Array Objects.
  //
  
  #include "libANGLE/VertexAttribute.h"
  
  namespace gl
  {
  
  // [OpenGL ES 3.1] (November 3, 2016) Section 20 Page 361
  // Table 20.2: Vertex Array Object State
  VertexBinding::VertexBinding() : mStride(16u), mDivisor(0), mOffset(0)
  {
  }
  
  VertexBinding::VertexBinding(VertexBinding &&binding)
  {
      *this = std::move(binding);
  }
  
  VertexBinding &VertexBinding::operator=(VertexBinding &&binding)
  {
      if (this != &binding)
      {
          mStride  = binding.mStride;
          mDivisor = binding.mDivisor;
          mOffset  = binding.mOffset;
          std::swap(binding.mBuffer, mBuffer);
      }
      return *this;
  }
  
  VertexAttribute::VertexAttribute(GLuint bindingIndex)
      : enabled(false),
        type(GL_FLOAT),
        size(4u),
        normalized(false),
        pureInteger(false),
        pointer(nullptr),
        relativeOffset(0),
        vertexAttribArrayStride(0),
        bindingIndex(bindingIndex)
  {
  }
  
  VertexAttribute::VertexAttribute(VertexAttribute &&attrib)
      : enabled(attrib.enabled),
        type(attrib.type),
        size(attrib.size),
        normalized(attrib.normalized),
        pureInteger(attrib.pureInteger),
        pointer(attrib.pointer),
        relativeOffset(attrib.relativeOffset),
        vertexAttribArrayStride(attrib.vertexAttribArrayStride),
        bindingIndex(attrib.bindingIndex)
  {
  }
  
  VertexAttribute &VertexAttribute::operator=(VertexAttribute &&attrib)
  {
      if (this != &attrib)
      {
          enabled                 = attrib.enabled;
          type                    = attrib.type;
          size                    = attrib.size;
          normalized              = attrib.normalized;
          pureInteger             = attrib.pureInteger;
          pointer                 = attrib.pointer;
          relativeOffset          = attrib.relativeOffset;
          vertexAttribArrayStride = attrib.vertexAttribArrayStride;
          bindingIndex            = attrib.bindingIndex;
      }
      return *this;
  }
  
  size_t ComputeVertexAttributeTypeSize(const VertexAttribute& attrib)
  {
      GLuint size = attrib.size;
      switch (attrib.type)
      {
        case GL_BYTE:                        return size * sizeof(GLbyte);
        case GL_UNSIGNED_BYTE:               return size * sizeof(GLubyte);
        case GL_SHORT:                       return size * sizeof(GLshort);
        case GL_UNSIGNED_SHORT:              return size * sizeof(GLushort);
        case GL_INT:                         return size * sizeof(GLint);
        case GL_UNSIGNED_INT:                return size * sizeof(GLuint);
        case GL_INT_2_10_10_10_REV:          return 4;
        case GL_UNSIGNED_INT_2_10_10_10_REV: return 4;
        case GL_FIXED:                       return size * sizeof(GLfixed);
        case GL_HALF_FLOAT:                  return size * sizeof(GLhalf);
        case GL_FLOAT:                       return size * sizeof(GLfloat);
        default: UNREACHABLE();              return size * sizeof(GLfloat);
      }
  }
  
  size_t ComputeVertexAttributeStride(const VertexAttribute &attrib, const VertexBinding &binding)
  {
      // In ES 3.1, VertexAttribPointer will store the type size in the binding stride.
      // Hence, rendering always uses the binding's stride.
      return attrib.enabled ? binding.getStride() : 16u;
  }
  
  // Warning: you should ensure binding really matches attrib.bindingIndex before using this function.
  GLintptr ComputeVertexAttributeOffset(const VertexAttribute &attrib, const VertexBinding &binding)
  {
      return attrib.relativeOffset + binding.getOffset();
  }
  
  size_t ComputeVertexBindingElementCount(GLuint divisor, size_t drawCount, size_t instanceCount)
  {
      // For instanced rendering, we draw "instanceDrawCount" sets of "vertexDrawCount" vertices.
      //
      // A vertex attribute with a positive divisor loads one instanced vertex for every set of
      // non-instanced vertices, and the instanced vertex index advances once every "mDivisor"
      // instances.
      if (instanceCount > 0 && divisor > 0)
      {
          // When instanceDrawCount is not a multiple attrib.divisor, the division must round up.
          // For instance, with 5 non-instanced vertices and a divisor equal to 3, we need 2 instanced
          // vertices.
          return (instanceCount + divisor - 1u) / divisor;
      }
  
      return drawCount;
  }
  
  GLenum GetVertexAttributeBaseType(const VertexAttribute &attrib)
  {
      if (attrib.pureInteger)
      {
          switch (attrib.type)
          {
              case GL_BYTE:
              case GL_SHORT:
              case GL_INT:
                  return GL_INT;
  
              case GL_UNSIGNED_BYTE:
              case GL_UNSIGNED_SHORT:
              case GL_UNSIGNED_INT:
                  return GL_UNSIGNED_INT;
  
              default:
                  UNREACHABLE();
                  return GL_NONE;
          }
      }
      else
      {
          return GL_FLOAT;
      }
  }
  
  }  // namespace gl
  

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