private static String loadShader(String fileName) {
        StringBuilder shaderSource = new StringBuilder();
        BufferedReader shaderReader = null;

        try {
            shaderReader = new BufferedReader(new FileReader("./res/shaders/"
                    + fileName));
            String line;

            while ((line = shaderReader.readLine()) != null) {
                shaderSource.append(line).append("\n");
            }

            shaderReader.close();
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(1);
        }

        return shaderSource.toString();
    }