shaderClass.cpp

#include "shaderClass.h"

// Reads a text file and outputs a string with everything in the text file
std::string get_file_contents(const char* filename){
	std::ifstream file(filename);
	std::string str;
	std::string file_contents;
	while (std::getline(file, str))
	{
		file_contents += str;
		file_contents.push_back('\n');
	}
	return file_contents;
}

// Constructor that build the Shader Program from 2 different shaders
Shader::Shader(const char* vertexFile, const char* fragmentFile){
	std::string vertexCode = get_file_contents(vertexFile);
	std::string fragmentCode = get_file_contents(fragmentFile);

	// Convert the shader source strings into character arrays
	const char* vertexSource = vertexCode.c_str();
	const char* fragmentSource = fragmentCode.c_str();

	GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
	glShaderSource(vertexShader, 1, &vertexSource, NULL);
	glCompileShader(vertexShader);
	compileErrors(vertexShader, "VERTEX");

	GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(fragmentShader, 1, &fragmentSource, NULL);
	glCompileShader(fragmentShader);
	compileErrors(vertexShader, "FRAGMENT");

	ID = glCreateProgram();
	glAttachShader(ID, vertexShader);
	glAttachShader(ID, fragmentShader);
	glLinkProgram(ID);

	// Delete the now useless Vertex and Fragment Shader objects
	glDeleteShader(vertexShader);
	glDeleteShader(fragmentShader);

}

void Shader::Activate(){
	glUseProgram(ID);
}

void Shader::Delete(){
	glDeleteProgram(ID);
}

void Shader::compileErrors(unsigned int shader, const char* type){
	// Stores status of compilation
	GLint hasCompiled;
	// Character array to store error message in
	char infoLog[1024];
	if (type != "PROGRAM")
	{
		glGetShaderiv(shader, GL_COMPILE_STATUS, &hasCompiled);
		if (hasCompiled == GL_FALSE)
		{
			glGetShaderInfoLog(shader, 1024, NULL, infoLog);
			std::cout << "SHADER_COMPILATION_ERROR for:" << type << "\n" << infoLog << std::endl;
		}
	}
	else
	{
		glGetProgramiv(shader, GL_LINK_STATUS, &hasCompiled);
		if (hasCompiled == GL_FALSE)
		{
			glGetProgramInfoLog(shader, 1024, NULL, infoLog);
			std::cout << "SHADER_LINKING_ERROR for:" << type << "\n" << infoLog << std::endl;
		}
	}
}