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

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• Author : Geoff Lang
  Date : 2015-08-27 14:40:48
  Hash : 3cf12ce6
  Message : Implement the instanced draw calls in RendererGL. BUG=angleproject:1136 Change-Id: I1167365618bdc3ca37ac0f4c60809de32c7a9d78 Reviewed-on: https://chromium-review.googlesource.com/295733 Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>

• 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 class for mananging GLES 3 Vertex Array Objects.
  //
  
  #include "libANGLE/VertexAttribute.h"
  
  namespace gl
  {
  
  VertexAttribute::VertexAttribute()
      : enabled(false),
        type(GL_FLOAT),
        size(4),
        normalized(false),
        pureInteger(false),
        stride(0),
        pointer(NULL),
        divisor(0)
  {
  }
  
  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)
  {
      if (!attrib.enabled)
      {
          return 16;
      }
      return attrib.stride ? attrib.stride : ComputeVertexAttributeTypeSize(attrib);
  }
  
  size_t ComputeVertexAttributeElementCount(const VertexAttribute &attrib,
                                            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 && attrib.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 + attrib.divisor - 1u) / attrib.divisor;
      }
  
      return drawCount;
  }
  }