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/** ---------------------------------------------------------------------------
* @file: glslprogram.cpp
*
* Copyright (c) 2017 Yann Herklotz Grave <ymherklotz@gmail.com>
* MIT License, see LICENSE file for more details.
* ----------------------------------------------------------------------------
*/
#include "glslprogram.h"
#include <fstream>
#include <stdexcept>
#include <vector>
namespace yage
{
GlslProgram::~GlslProgram()
{
/// cleans up all the shaders and the program
if (fragment_shader_id_ != 0) {
glDeleteShader(fragment_shader_id_);
}
if (vertex_shader_id_ != 0) {
glDeleteShader(vertex_shader_id_);
}
if (program_id_ != 0) {
glDeleteProgram(program_id_);
}
}
void GlslProgram::compileShader(GLuint shader, const std::string &shaderContent)
{
// cast source to a c string to get the address of it and input it for
// compilation
const auto *vertex_source = (const GLchar *)shaderContent.c_str();
glShaderSource(shader, 1, &vertex_source, nullptr);
glCompileShader(shader);
// check if compilation was successful
GLint is_compiled = 0;
glGetShaderiv(shader, GL_COMPILE_STATUS, (int *)&is_compiled);
// if it isn't compiled throw exception to clean up
if (is_compiled == GL_FALSE) {
GLint max_length = 0;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &max_length);
std::vector<GLchar> error_log(max_length);
glGetShaderInfoLog(shader, max_length, &max_length, &error_log[0]);
std::string error_log_str((const char *)&error_log[0]);
std::string shaderName;
if (shader == vertex_shader_id_)
shaderName = "vertex shader";
else
shaderName = "fragment shader";
throw std::runtime_error("Couldn't compile the " + shaderName + " : " +
error_log_str);
}
}
void GlslProgram::compileShaderFromFile(GLuint shader,
const std::string &file_path)
{
// get a string with the input from the shader file
std::ifstream file(file_path);
if (!file.is_open()) {
throw std::runtime_error("Failed to open '" + file_path + "'");
}
std::string content = "";
std::string line;
while (std::getline(file, line)) {
content += line + "\n";
}
file.close();
compileShader(shader, content);
}
void GlslProgram::initShaderId()
{
// create the program that will be run on GPU
program_id_ = glCreateProgram();
// create vertex shader
vertex_shader_id_ = glCreateShader(GL_VERTEX_SHADER);
if (vertex_shader_id_ == 0) {
throw std::runtime_error("Vertex shader failed to be created");
}
// create fragment shader
fragment_shader_id_ = glCreateShader(GL_FRAGMENT_SHADER);
if (fragment_shader_id_ == 0) {
throw std::runtime_error("Fragment shader failed to be created");
}
}
void GlslProgram::compileShaders(const std::string &vertexShader,
const std::string fragmentShader)
{
initShaderId();
compileShader(vertex_shader_id_, vertexShader);
compileShader(fragment_shader_id_, fragmentShader);
}
void GlslProgram::compileShadersFromFile(
const std::string &vertex_shader_path,
const std::string &fragment_shader_path)
{
initShaderId();
// compile the two shaders
compileShaderFromFile(vertex_shader_id_, vertex_shader_path);
compileShaderFromFile(fragment_shader_id_, fragment_shader_path);
}
void GlslProgram::linkShaders()
{
// attach the shaders that we want
glAttachShader(program_id_, vertex_shader_id_);
glAttachShader(program_id_, fragment_shader_id_);
// link our program
glLinkProgram(program_id_);
GLint is_linked = 0;
glGetProgramiv(program_id_, GL_LINK_STATUS, (int *)&is_linked);
if (is_linked == GL_FALSE) {
GLint max_length = 0;
glGetProgramiv(program_id_, GL_INFO_LOG_LENGTH, &max_length);
std::vector<GLchar> error_log(max_length);
glGetProgramInfoLog(program_id_, max_length, &max_length,
&error_log[0]);
std::string error_log_str((const char *)&error_log[0]);
throw std::runtime_error("Could not link program : " + error_log_str);
}
// detach shaders after successful link
glDetachShader(program_id_, fragment_shader_id_);
glDetachShader(program_id_, vertex_shader_id_);
// we can then delete the shaders once we have the program
glDeleteShader(fragment_shader_id_);
glDeleteShader(vertex_shader_id_);
}
void GlslProgram::addAttribute(const std::string &attribute_name)
{
glBindAttribLocation(program_id_, attribute_index_++,
attribute_name.c_str());
}
GLint GlslProgram::getUniformLocation(const std::string &uniform_name)
{
GLint location = glGetUniformLocation(program_id_, uniform_name.c_str());
if ((GLuint)location == GL_INVALID_INDEX) {
throw std::runtime_error("'" + uniform_name + "' not found");
}
return location;
}
void GlslProgram::use()
{
glUseProgram(program_id_);
for (int i = 0; i < attribute_index_; ++i) {
glEnableVertexAttribArray(i);
}
}
void GlslProgram::unuse()
{
for (int i = 0; i < attribute_index_; ++i) {
glDisableVertexAttribArray(i);
}
glUseProgram(0);
}
void GlslProgram::defaultSetup()
{
std::string vertexShader =
"#version 130\n\nin vec2 vertex_position;\nin vec4 vertex_colour;\nin "
"vec2 vertex_uv;\n\nout vec2 fragment_position;\nout vec4 "
"fragment_colour;\nout vec2 fragment_uv;\n\nuniform mat4 P;\n\nvoid "
"main()\n{\n gl_Position.xy = (P*vec4(vertex_position, 0.0, "
"1.0)).xy;\n gl_Position.z = 0.0;\n gl_Position.w = 1.0;\n\n "
"fragment_position = vertex_position;\n fragment_colour = "
"vertex_colour;\n fragment_uv = vec2(vertex_uv.x, "
"1-vertex_uv.y);\n\n}";
std::string fragmentShader =
"#version 130\n\nin vec2 fragment_position;\nin vec4 "
"fragment_colour;\nin vec2 fragment_uv;\n\nout vec4 colour;\n\nuniform "
"sampler2D texture_sampler;\n\nvoid main()\n{\n vec4 texture_color "
"= texture(texture_sampler, fragment_uv);\n\n colour = "
"texture_color;\n}";
compileShaders(vertexShader, fragmentShader);
addAttribute("vertex_position");
addAttribute("vertex_colour");
addAttribute("vertex_uv");
linkShaders();
}
} // namespace yage
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