shader.cpp

#include <cstdio>
#include <string>
#include <vector>
#include <iostream>
#include <fstream>

#include <GL/glew.h>

#include "shader.h"

int CompileShader(const char *ShaderPath, const GLuint ShaderID)
{
	// Read shader code from file
	std::string ShaderCode;
	std::ifstream ShaderStream (ShaderPath, std::ios::in);
	if (ShaderStream.is_open()) {
		std::string Line = "";
		while (getline(ShaderStream, Line)) {
			ShaderCode += "\n" + Line;
        }
		ShaderStream.close();
	}
    else {
        std::cerr << "Cannot open " << ShaderPath << ". Are you in the right directory?" << std::endl;
		return 0;
	}

	// Compile Shader
	char const *SourcePointer = ShaderCode.c_str();
	glShaderSource(ShaderID, 1, &SourcePointer , NULL);
	glCompileShader(ShaderID);

	// Check Shader
	GLint Result = GL_FALSE;
	int InfoLogLength;

	glGetShaderiv(ShaderID, GL_COMPILE_STATUS, &Result);
	glGetShaderiv(ShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
    printf("compiled shader %d %d\n", Result, InfoLogLength);
	if ( InfoLogLength > 1 ) {
        char ShaderErrorMessage[InfoLogLength+1];
		glGetShaderInfoLog( ShaderID,
                            InfoLogLength,
                            NULL,
                            &ShaderErrorMessage[0]);
        std::cerr << &ShaderErrorMessage[0] << std::endl;
        return 0;
	}
    return 1;
}

GLuint LoadShaders(const char * vertex_file_path,
                   const char * fragment_file_path )
{
	// Create the shaders
	GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
	GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
	std::cout << "Created Shaders" << std::endl;
    // Compile both shaders. Exit if compile errors.
    if ( !CompileShader(vertex_file_path, VertexShaderID)
         || !CompileShader(fragment_file_path, FragmentShaderID) ) {
        return 0;
    }

	// Link the program
	GLuint ProgramID = glCreateProgram();
	glAttachShader(ProgramID, VertexShaderID);
	glAttachShader(ProgramID, FragmentShaderID);
	glLinkProgram(ProgramID);

	// Check the program
	GLint Result = GL_FALSE;
	int InfoLogLength;
    
	glGetProgramiv(ProgramID, GL_LINK_STATUS, &Result);
	glGetProgramiv(ProgramID, GL_INFO_LOG_LENGTH, &InfoLogLength);
	if ( InfoLogLength > 0 ) {
		std::vector<char> ProgramErrorMessage(InfoLogLength+1);
		glGetProgramInfoLog(ProgramID, InfoLogLength, NULL, &ProgramErrorMessage[0]);
        std::cerr << &ProgramErrorMessage[0] << std::endl;
	}

	glDeleteShader(VertexShaderID);
	glDeleteShader(FragmentShaderID);

	return ProgramID;
}