cc/output/dynamic_geometry_binding.cc

// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cc/output/dynamic_geometry_binding.h"

#include <stdint.h>

#include "gpu/command_buffer/client/gles2_interface.h"
#include "ui/gfx/geometry/quad_f.h"
#include "ui/gfx/geometry/rect_f.h"

namespace cc {

DynamicGeometryBinding::DynamicGeometryBinding(gpu::gles2::GLES2Interface* gl)
    : gl_(gl), quad_vertices_vbo_(0), quad_elements_vbo_(0) {
  GeometryBindingQuad quads[1];
  GeometryBindingQuadIndex quad_indices[1];

  static_assert(sizeof(GeometryBindingQuad) == 24 * sizeof(float),
                "struct Quad should be densely packed");
  static_assert(sizeof(GeometryBindingQuadIndex) == 6 * sizeof(uint16_t),
                "struct QuadIndex should be densely packed");

  gl_->GenBuffers(1, &quad_vertices_vbo_);
  gl_->GenBuffers(1, &quad_elements_vbo_);

  gl_->BindBuffer(GL_ARRAY_BUFFER, quad_vertices_vbo_);
  gl_->BufferData(GL_ARRAY_BUFFER, sizeof(GeometryBindingQuad) * 1, quads,
                  GL_DYNAMIC_DRAW);

  gl_->BindBuffer(GL_ELEMENT_ARRAY_BUFFER, quad_elements_vbo_);
  gl_->BufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(GeometryBindingQuadIndex) * 1,
                  &quad_indices, GL_DYNAMIC_DRAW);
}

void DynamicGeometryBinding::InitializeCustomQuad(const gfx::QuadF& quad) {
  float uv[] = {0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f};
  InitializeCustomQuadWithUVs(quad, uv);
}

void DynamicGeometryBinding::InitializeCustomQuadWithUVs(const gfx::QuadF& quad,
                                                         const float uv[8]) {
  GeometryBindingVertex v0 = {
      {quad.p1().x(), quad.p1().y(), 0.0f}, {uv[0], uv[1]}, 0.0f};
  GeometryBindingVertex v1 = {
      {quad.p2().x(), quad.p2().y(), 0.0f}, {uv[2], uv[3]}, 1.0f};
  GeometryBindingVertex v2 = {
      {quad.p3().x(), quad.p3().y(), 0.0f}, {uv[4], uv[5]}, 2.0f};
  GeometryBindingVertex v3 = {
      {quad.p4().x(), quad.p4().y(), 0.0f}, {uv[6], uv[7]}, 3.0f};

  GeometryBindingQuad local_quad = {v0, v1, v2, v3};
  GeometryBindingQuadIndex quad_index(
      static_cast<uint16_t>(0), static_cast<uint16_t>(1),
      static_cast<uint16_t>(2), static_cast<uint16_t>(3),
      static_cast<uint16_t>(0), static_cast<uint16_t>(2));

  gl_->BufferSubData(GL_ARRAY_BUFFER, 0, sizeof(GeometryBindingQuad),
                     &local_quad);
  gl_->BufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0,
                     sizeof(GeometryBindingQuadIndex), &quad_index);
}

void DynamicGeometryBinding::PrepareForDraw() {
  SetupGLContext(gl_, quad_elements_vbo_, quad_vertices_vbo_);
}

}  // namespace cc