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      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 "third_party/khronos/GLES2/gl2.h"
     10 #include "ui/gfx/rect_f.h"
     11 
     12 namespace cc {
     13 
     14 GeometryBinding::GeometryBinding(gpu::gles2::GLES2Interface* gl,
     15                                  const gfx::RectF& quad_vertex_rect)
     16     : gl_(gl), quad_vertices_vbo_(0), quad_elements_vbo_(0) {
     17   struct Vertex {
     18     float a_position[3];
     19     float a_texCoord[2];
     20     // Index of the vertex, divide by 4 to have the matrix for this quad.
     21     float a_index;
     22   };
     23   struct Quad {
     24     Vertex v0, v1, v2, v3;
     25   };
     26   struct QuadIndex {
     27     uint16 data[6];
     28   };
     29 
     30   COMPILE_ASSERT(sizeof(Quad) == 24 * sizeof(float),  // NOLINT(runtime/sizeof)
     31                  struct_is_densely_packed);
     32   COMPILE_ASSERT(
     33       sizeof(QuadIndex) == 6 * sizeof(uint16_t),  // NOLINT(runtime/sizeof)
     34       struct_is_densely_packed);
     35 
     36   Quad quad_list[8];
     37   QuadIndex quad_index_list[8];
     38   for (int i = 0; i < 8; i++) {
     39     Vertex v0 = {{quad_vertex_rect.x(), quad_vertex_rect.bottom(), 0.0f, },
     40                  {0.0f, 1.0f, }, i * 4.0f + 0.0f};
     41     Vertex v1 = {{quad_vertex_rect.x(), quad_vertex_rect.y(), 0.0f, },
     42                  {0.0f, 0.0f, }, i * 4.0f + 1.0f};
     43     Vertex v2 = {{quad_vertex_rect.right(), quad_vertex_rect.y(), 0.0f, },
     44                  {1.0f, .0f, }, i * 4.0f + 2.0f};
     45     Vertex v3 = {{quad_vertex_rect.right(), quad_vertex_rect.bottom(), 0.0f, },
     46                  {1.0f, 1.0f, }, i * 4.0f + 3.0f};
     47     Quad x = {v0, v1, v2, v3};
     48     quad_list[i] = x;
     49     QuadIndex y = {
     50         {static_cast<uint16>(0 + 4 * i), static_cast<uint16>(1 + 4 * i),
     51          static_cast<uint16>(2 + 4 * i), static_cast<uint16>(3 + 4 * i),
     52          static_cast<uint16>(0 + 4 * i), static_cast<uint16>(2 + 4 * i)}};
     53     quad_index_list[i] = y;
     54   }
     55 
     56   gl_->GenBuffers(1, &quad_vertices_vbo_);
     57   gl_->GenBuffers(1, &quad_elements_vbo_);
     58   GLC(gl_, gl_->BindBuffer(GL_ARRAY_BUFFER, quad_vertices_vbo_));
     59   GLC(gl_,
     60       gl_->BufferData(
     61           GL_ARRAY_BUFFER, sizeof(quad_list), quad_list, GL_STATIC_DRAW));
     62   GLC(gl_, gl_->BindBuffer(GL_ELEMENT_ARRAY_BUFFER, quad_elements_vbo_));
     63   GLC(gl_,
     64       gl_->BufferData(GL_ELEMENT_ARRAY_BUFFER,
     65                       sizeof(quad_index_list),
     66                       quad_index_list,
     67                       GL_STATIC_DRAW));
     68 }
     69 
     70 GeometryBinding::~GeometryBinding() {
     71   gl_->DeleteBuffers(1, &quad_vertices_vbo_);
     72   gl_->DeleteBuffers(1, &quad_elements_vbo_);
     73 }
     74 
     75 void GeometryBinding::PrepareForDraw() {
     76   GLC(gl_, gl_->BindBuffer(GL_ELEMENT_ARRAY_BUFFER, quad_elements_vbo_));
     77 
     78   GLC(gl_, gl_->BindBuffer(GL_ARRAY_BUFFER, quad_vertices_vbo_));
     79   // OpenGL defines the last parameter to VertexAttribPointer as type
     80   // "const GLvoid*" even though it is actually an offset into the buffer
     81   // object's data store and not a pointer to the client's address space.
     82   const void* offsets[3] = {
     83       0, reinterpret_cast<const void*>(
     84              3 * sizeof(float)),  // NOLINT(runtime/sizeof)
     85       reinterpret_cast<const void*>(5 *
     86                                     sizeof(float)),  // NOLINT(runtime/sizeof)
     87   };
     88 
     89   GLC(gl_,
     90       gl_->VertexAttribPointer(PositionAttribLocation(),
     91                                3,
     92                                GL_FLOAT,
     93                                false,
     94                                6 * sizeof(float),  // NOLINT(runtime/sizeof)
     95                                offsets[0]));
     96   GLC(gl_,
     97       gl_->VertexAttribPointer(TexCoordAttribLocation(),
     98                                2,
     99                                GL_FLOAT,
    100                                false,
    101                                6 * sizeof(float),  // NOLINT(runtime/sizeof)
    102                                offsets[1]));
    103   GLC(gl_,
    104       gl_->VertexAttribPointer(TriangleIndexAttribLocation(),
    105                                1,
    106                                GL_FLOAT,
    107                                false,
    108                                6 * sizeof(float),  // NOLINT(runtime/sizeof)
    109                                offsets[2]));
    110   GLC(gl_, gl_->EnableVertexAttribArray(PositionAttribLocation()));
    111   GLC(gl_, gl_->EnableVertexAttribArray(TexCoordAttribLocation()));
    112   GLC(gl_, gl_->EnableVertexAttribArray(TriangleIndexAttribLocation()));
    113 }
    114 
    115 }  // namespace cc
    116