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/* ----------------------------------------------------------------------------
* glslprogram.cpp
*
* Copyright (c) 2017 Yann Herklotz Grave <ymherklotz@gmail.com> -- MIT License
* See file LICENSE for more details
* ----------------------------------------------------------------------------
*/
#include "glslprogram.hpp"
#include <fstream>
#include <stdexcept>
#include <vector>
namespace yage {
GlslProgram::~GlslProgram() {
// cleanup 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(const 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();
// cast source to a c string to get the address of it and input it for
// compilation
const GLchar* vertex_source = (const GLchar*)content.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]);
throw std::runtime_error("Couldn't compile " + file_path + " : " +
error_log_str);
}
}
void GlslProgram::compileShaders(const std::string& vertex_shader_path,
const std::string& fragment_shader_path) {
// 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");
// compile the two shaders
compileShader(vertex_shader_id_, vertex_shader_path);
compileShader(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);
}
} // yage
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