cc/output/geometry_binding.cc

   1 // Copyright 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/output/geometry_binding.h"
   6
   7 #include "cc/output/gl_renderer.h"  // For the GLC() macro.
   8 #include "gpu/command_buffer/client/gles2_interface.h"
   9 #include "ui/gfx/geometry/rect_f.h"
  10
  11 namespace cc {
  12
  13 GeometryBinding::GeometryBinding(gpu::gles2::GLES2Interface* gl,
  14                                  const gfx::RectF& quad_vertex_rect)
  15     : gl_(gl), quad_vertices_vbo_(0), quad_elements_vbo_(0) {
  16   struct Vertex {
  17     float a_position[3];
  18     float a_texCoord[2];
  19     // Index of the vertex, divide by 4 to have the matrix for this quad.
  20     float a_index;
  21   };
  22   struct Quad {
  23     Vertex v0, v1, v2, v3;
  24   };
  25   struct QuadIndex {
  26     uint16 data[6];
  27   };
  28
  29   static_assert(sizeof(Quad) == 24 * sizeof(float),
  30                 "struct Quad should be densely packed");
  31   static_assert(sizeof(QuadIndex) == 6 * sizeof(uint16_t),
  32                 "struct QuadIndex should be densely packed");
  33
  34   Quad quad_list[8];
  35   QuadIndex quad_index_list[8];
  36   for (int i = 0; i < 8; i++) {
  37     Vertex v0 = {{quad_vertex_rect.x(), quad_vertex_rect.bottom(), 0.0f, },
  38                  {0.0f, 1.0f, }, i * 4.0f + 0.0f};
  39     Vertex v1 = {{quad_vertex_rect.x(), quad_vertex_rect.y(), 0.0f, },
  40                  {0.0f, 0.0f, }, i * 4.0f + 1.0f};
  41     Vertex v2 = {{quad_vertex_rect.right(), quad_vertex_rect.y(), 0.0f, },
  42                  {1.0f, .0f, }, i * 4.0f + 2.0f};
  43     Vertex v3 = {{quad_vertex_rect.right(), quad_vertex_rect.bottom(), 0.0f, },
  44                  {1.0f, 1.0f, }, i * 4.0f + 3.0f};
  45     Quad x = {v0, v1, v2, v3};
  46     quad_list[i] = x;
  47     QuadIndex y = {
  48         {static_cast<uint16>(0 + 4 * i), static_cast<uint16>(1 + 4 * i),
  49          static_cast<uint16>(2 + 4 * i), static_cast<uint16>(3 + 4 * i),
  50          static_cast<uint16>(0 + 4 * i), static_cast<uint16>(2 + 4 * i)}};
  51     quad_index_list[i] = y;
  52   }
  53
  54   gl_->GenBuffers(1, &quad_vertices_vbo_);
  55   gl_->GenBuffers(1, &quad_elements_vbo_);
  56   GLC(gl_, gl_->BindBuffer(GL_ARRAY_BUFFER, quad_vertices_vbo_));
  57   GLC(gl_,
  58       gl_->BufferData(
  59           GL_ARRAY_BUFFER, sizeof(quad_list), quad_list, GL_STATIC_DRAW));
  60   GLC(gl_, gl_->BindBuffer(GL_ELEMENT_ARRAY_BUFFER, quad_elements_vbo_));
  61   GLC(gl_,
  62       gl_->BufferData(GL_ELEMENT_ARRAY_BUFFER,
  63                       sizeof(quad_index_list),
  64                       quad_index_list,
  65                       GL_STATIC_DRAW));
  66 }
  67
  68 GeometryBinding::~GeometryBinding() {
  69   gl_->DeleteBuffers(1, &quad_vertices_vbo_);
  70   gl_->DeleteBuffers(1, &quad_elements_vbo_);
  71 }
  72
  73 void GeometryBinding::PrepareForDraw() {
  74   GLC(gl_, gl_->BindBuffer(GL_ELEMENT_ARRAY_BUFFER, quad_elements_vbo_));
  75
  76   GLC(gl_, gl_->BindBuffer(GL_ARRAY_BUFFER, quad_vertices_vbo_));
  77   // OpenGL defines the last parameter to VertexAttribPointer as type
  78   // "const GLvoid*" even though it is actually an offset into the buffer
  79   // object's data store and not a pointer to the client's address space.
  80   const void* offsets[3] = {
  81       0,
  82       reinterpret_cast<const void*>(3 * sizeof(float)),
  83       reinterpret_cast<const void*>(5 * sizeof(float)),
  84   };
  85
  86   GLC(gl_, gl_->VertexAttribPointer(PositionAttribLocation(), 3, GL_FLOAT,
  87                                     false, 6 * sizeof(float), offsets[0]));
  88   GLC(gl_, gl_->VertexAttribPointer(TexCoordAttribLocation(), 2, GL_FLOAT,
  89                                     false, 6 * sizeof(float), offsets[1]));
  90   GLC(gl_, gl_->VertexAttribPointer(TriangleIndexAttribLocation(), 1, GL_FLOAT,
  91                                     false, 6 * sizeof(float), offsets[2]));
  92   GLC(gl_, gl_->EnableVertexAttribArray(PositionAttribLocation()));
  93   GLC(gl_, gl_->EnableVertexAttribArray(TexCoordAttribLocation()));
  94   GLC(gl_, gl_->EnableVertexAttribArray(TriangleIndexAttribLocation()));
  95 }
  96
  97 }  // namespace cc