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      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.
      9 static 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.
     17 static const float kTextureCoords[8] = {
     18   0, 0,
     19   0, 1,
     20   1, 0,
     21   1, 1,
     22 };
     23 
     24 // Buffer size for compile errors.
     25 static const unsigned int kErrorSize = 4096;
     26 
     27 GPUPainter::GPUPainter()
     28     : surface_(NULL),
     29       context_(NULL) {
     30 }
     31 
     32 GPUPainter::~GPUPainter() {
     33 }
     34 
     35 void GPUPainter::SetGLContext(gfx::GLSurface* surface,
     36                               gfx::GLContext* context) {
     37   surface_ = surface;
     38   context_ = context;
     39 }
     40 
     41 GLuint 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 
     57 GLuint 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