1// Copyright (c) 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 "base/logging.h"
6#include "media/tools/shader_bench/gpu_painter.h"
7
8// Vertices for a full screen quad.
9static const float kVertices[8] = {
10  -1.f, 1.f,
11  -1.f, -1.f,
12  1.f, 1.f,
13  1.f, -1.f,
14};
15
16// Texture Coordinates mapping the entire texture.
17static const float kTextureCoords[8] = {
18  0, 0,
19  0, 1,
20  1, 0,
21  1, 1,
22};
23
24// Buffer size for compile errors.
25static const unsigned int kErrorSize = 4096;
26
27GPUPainter::GPUPainter()
28    : surface_(NULL),
29      context_(NULL) {
30}
31
32GPUPainter::~GPUPainter() {
33}
34
35void GPUPainter::SetGLContext(gfx::GLSurface* surface,
36                              gfx::GLContext* context) {
37  surface_ = surface;
38  context_ = context;
39}
40
41GLuint GPUPainter::LoadShader(unsigned type, const char* shader_source) {
42  GLuint shader = glCreateShader(type);
43  glShaderSource(shader, 1, &shader_source, NULL);
44  glCompileShader(shader);
45  int result = GL_FALSE;
46  glGetShaderiv(shader, GL_COMPILE_STATUS, &result);
47  if (!result) {
48    char log[kErrorSize];
49    int len;
50    glGetShaderInfoLog(shader, kErrorSize - 1, &len, log);
51    log[kErrorSize - 1] = 0;
52    LOG(FATAL) << "Shader did not compile: " << log;
53  }
54  return shader;
55}
56
57GLuint GPUPainter::CreateShaderProgram(const char* vertex_shader_source,
58                                       const char* fragment_shader_source) {
59
60  // Create vertex and pixel shaders.
61  GLuint vertex_shader = LoadShader(GL_VERTEX_SHADER, vertex_shader_source);
62  GLuint fragment_shader =
63      LoadShader(GL_FRAGMENT_SHADER, fragment_shader_source);
64
65  // Create program and attach shaders.
66  GLuint program = glCreateProgram();
67  glAttachShader(program, vertex_shader);
68  glAttachShader(program, fragment_shader);
69  glDeleteShader(vertex_shader);
70  glDeleteShader(fragment_shader);
71  glLinkProgram(program);
72  int result = GL_FALSE;
73  glGetProgramiv(program, GL_LINK_STATUS, &result);
74  if (!result) {
75    char log[kErrorSize];
76    int len;
77    glGetProgramInfoLog(program, kErrorSize - 1, &len, log);
78    log[kErrorSize - 1] = 0;
79    LOG(FATAL) << "Program did not link: " << log;
80  }
81  glUseProgram(program);
82
83  // Set common vertex parameters.
84  int pos_location = glGetAttribLocation(program, "in_pos");
85  glEnableVertexAttribArray(pos_location);
86  glVertexAttribPointer(pos_location, 2, GL_FLOAT, GL_FALSE, 0, kVertices);
87
88  int tc_location = glGetAttribLocation(program, "in_tc");
89  glEnableVertexAttribArray(tc_location);
90  glVertexAttribPointer(tc_location, 2, GL_FLOAT, GL_FALSE, 0, kTextureCoords);
91  return program;
92}
93