Benchmark tool for GPU-accelerated video rendering

media/tools/shader_bench/gpu_painter.cc

+// Copyright (c) 2010 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 "media/tools/shader_bench/gpu_painter.h"
+
+// Vertices for a full screen quad.
+static const float kVertices[8] = {
+  -1.f, 1.f,
+  -1.f, -1.f,
+  1.f, 1.f,
+  1.f, -1.f,
+};
+
+// Texture Coordinates mapping the entire texture.
+static const float kTextureCoords[8] = {
+  0, 0,
+  0, 1,
+  1, 0,
+  1, 1,
+};
+
+// Buffer size for compile errors.
+static const unsigned int kErrorSize = 4096;
+
+void GPUPainter::SetGLContext(gfx::GLContext* context) {
+  context_ = context;
+}
+
+GLuint GPUPainter::LoadShader(gfx::GLContext* context, unsigned type,
+                              const char* shader_source) {
+  GLuint shader = glCreateShader(type);
+  glShaderSource(shader, 1, &shader_source, NULL);
+  glCompileShader(shader);
+  int result = GL_FALSE;
+  glGetShaderiv(shader, GL_COMPILE_STATUS, &result);
+  if (!result) {
+    char log[kErrorSize];
+    int len;
+    glGetShaderInfoLog(shader, kErrorSize - 1, &len, log);
+    log[kErrorSize - 1] = 0;
+    printf("Shader did not compile: %s\n", log);
+  }
+  return shader;
+}
+
+GLuint GPUPainter::CreateShaderProgram(
+    gfx::GLContext* context, const char* vertex_shader_source,
+    const char* fragment_shader_source) {
+
+  // Create vertex and pixel shaders.
+  GLuint vertex_shader =
+      LoadShader(context, GL_VERTEX_SHADER, vertex_shader_source);
+  GLuint fragment_shader =
+      LoadShader(context, GL_FRAGMENT_SHADER, fragment_shader_source);
+
+  // Create program and attach shaders.
+  GLuint program = glCreateProgram();
+  glAttachShader(program, vertex_shader);
+  glAttachShader(program, fragment_shader);
+  glDeleteShader(vertex_shader);
+  glDeleteShader(fragment_shader);
+  glLinkProgram(program);
+  int result = GL_FALSE;
+  glGetProgramiv(program, GL_LINK_STATUS, &result);
+  if (!result) {
+    char log[kErrorSize];
+    int len;
+    glGetProgramInfoLog(program, kErrorSize - 1, &len, log);
+    log[kErrorSize - 1] = 0;
+    printf("Program did not link: %s\n", log);
+  }
+  glUseProgram(program);
+
+  // Set common vertex parameters.
+  int pos_location = glGetAttribLocation(program, "in_pos");
+  glEnableVertexAttribArray(pos_location);
+  glVertexAttribPointer(pos_location, 2, GL_FLOAT, GL_FALSE, 0, kVertices);
+
+  int tc_location = glGetAttribLocation(program, "in_tc");
+  glEnableVertexAttribArray(tc_location);
+  glVertexAttribPointer(tc_location, 2, GL_FLOAT, GL_FALSE, 0,
+                        kTextureCoords);
+  return program;
+}