shaderClass.cpp

#include "shaderClass.h"

// Read our Shaders from file
std::string getFileContents(const char* filename) {

	std::ifstream in(filename, std::ios::binary);

	if (in) {
		std::string contents;
		in.seekg(0, std::ios::end);					// Move cursor to end of file
		contents.resize(in.tellg());				// Resize based on cursor position
		in.seekg(0, std::ios::beg);					// Move cursor to start of file
		in.read(&contents[0], contents.size());		// Read the contents, save the file, return string
		in.close();
		return contents;
	}

	throw(errno);
}

// Constructor to build the Shader Program for 2 different Shaders
Shader::Shader(const char* vertexFile, const char* fragmentFile) {

	// Assign the file contents to a string
	std::string vertexCode = getFileContents(vertexFile);
	std::string fragmentCode = getFileContents(fragmentFile);

	// Move those file contents into a char array
	const char* vertexSource = vertexCode.c_str();
	const char* fragmentSource = fragmentCode.c_str();

	// Create vector shader object and get refrence
	GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
	// Attach vertex shader to vector source
	glShaderSource(vertexShader, 1, &vertexSource, NULL);
	// Compile the shader into machine code
	glCompileShader(vertexShader);

	// Create fragment shader object and get refrence
	GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
	// Attach fragment shader to fragment shader source
	glShaderSource(fragmentShader, 1, &fragmentSource, NULL);
	// Compile the fragment shader into machine code
	glCompileShader(fragmentShader);

	// Create a shader program and get its refrence
	ID = glCreateProgram();

	// Attach vertex shader amd fragment shader to the shader program
	glAttachShader(ID, vertexShader);
	glAttachShader(ID, fragmentShader);

	// Wrap/Link shaders into the shader program
	glLinkProgram(ID);

	// Delete the vertex and fragment shaders as they are now in our shader program
	glDeleteShader(vertexShader);
	glDeleteShader(fragmentShader);
}

// Tell OpenGL which Shader Program to use
void Shader::Activate() {
	glUseProgram(ID);
}

// Remove our Shader Program
void Shader::Delete() {
	glDeleteProgram(ID);
}