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// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ui/gl/gl_helper.h"
#include <string>
#include "base/check_op.h"
#include "ui/gl/gl_context.h"
#include "ui/gl/scoped_binders.h"
namespace gl {
// static
GLuint GLHelper::CompileShader(GLenum type, const char* src) {
GLuint shader = glCreateShader(type);
// Load the shader source.
glShaderSource(shader, 1, &src, nullptr);
// Compile the shader.
glCompileShader(shader);
return shader;
}
// static
GLuint GLHelper::LoadShader(GLenum type, const char* src) {
GLuint shader = CompileShader(type, src);
// Check the compile status.
GLint value = 0;
glGetShaderiv(shader, GL_COMPILE_STATUS, &value);
if (!value) {
char buffer[1024];
GLsizei length = 0;
glGetShaderInfoLog(shader, sizeof(buffer), &length, buffer);
std::string log(buffer, length);
DCHECK_EQ(1, value) << "Error compiling shader: " << log;
glDeleteShader(shader);
shader = 0;
}
return shader;
}
// static
GLuint GLHelper::LinkProgram(GLuint vertex_shader, GLuint fragment_shader) {
// Create the program object.
GLuint program = glCreateProgram();
glAttachShader(program, vertex_shader);
glAttachShader(program, fragment_shader);
// Link the program.
glLinkProgram(program);
return program;
}
// static
GLuint GLHelper::SetupProgram(GLuint vertex_shader, GLuint fragment_shader) {
GLuint program = LinkProgram(vertex_shader, fragment_shader);
// Check the link status.
GLint linked = 0;
glGetProgramiv(program, GL_LINK_STATUS, &linked);
if (!linked) {
char buffer[1024];
GLsizei length = 0;
glGetProgramInfoLog(program, sizeof(buffer), &length, buffer);
std::string log(buffer, length);
DCHECK_EQ(1, linked) << "Error linking program: " << log;
glDeleteProgram(program);
program = 0;
}
return program;
}
// static
GLuint GLHelper::SetupQuadVertexBuffer() {
GLuint vertex_buffer = 0;
glGenBuffersARB(1, &vertex_buffer);
ScopedBufferBinder buffer_binder(GL_ARRAY_BUFFER, vertex_buffer);
GLfloat data[] = {-1.f, -1.f, 1.f, -1.f, -1.f, 1.f, 1.f, 1.f};
glBufferData(GL_ARRAY_BUFFER, sizeof(data), data, GL_STATIC_DRAW);
return vertex_buffer;
}
// static
void GLHelper::DrawQuad(GLuint vertex_buffer) {
ScopedBufferBinder buffer_binder(GL_ARRAY_BUFFER, vertex_buffer);
ScopedVertexAttribArray vertex_attrib_array(0, 2, GL_FLOAT, GL_FALSE,
sizeof(GLfloat) * 2, 0);
ScopedCapability disable_blending(GL_BLEND, GL_FALSE);
ScopedCapability disable_culling(GL_CULL_FACE, GL_FALSE);
ScopedCapability disable_dithering(GL_DITHER, GL_FALSE);
ScopedCapability disable_depth_test(GL_DEPTH_TEST, GL_FALSE);
ScopedCapability disable_scissor_test(GL_SCISSOR_TEST, GL_FALSE);
ScopedColorMask color_mask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}
} // namespace gl
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