/* ----- my texture loading functions (will eventually be one function)
//texture loading functions
GLuint loadTexture()
    {
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);  
	GLuint texture;
	glGenTextures(1, &texture);
	glActiveTexture(GL_TEXTURE0);
        glEnable(GL_TEXTURE_2D);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT_OES);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_MIRRORED_REPEAT_OES);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
	
    //load texture from web
    NSString *fileNameString = [NSString stringWithFormat:@"%@",textureName];
    NSString *texturePathString = [pathString stringByAppendingString:[NSString stringWithFormat:@"%@", fileNameString]];
    NSData *texData = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:[NSString stringWithFormat:@"%@", texturePathString]]];
        
		UIImage *image = [[UIImage alloc] initWithData:texData];
		if (image == nil)
			return 0;
		
		GLuint width = CGImageGetWidth(image.CGImage);
		GLuint height = CGImageGetHeight(image.CGImage);
		CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
		void *imageData = malloc( height * width * 4 );
		CGContextRef context = CGBitmapContextCreate( imageData, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big );
		CGColorSpaceRelease( colorSpace );
		CGContextClearRect( context, CGRectMake( 0, 0, width, height ) );
		CGContextDrawImage( context, CGRectMake( 0, 0, width, height ), image.CGImage );
		
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData);
		CGContextRelease(context);
		
		free(imageData);
		[image release];
	return texture;
    }
}

//second texture loading code, just a 2d now, will be cube map later
GLuint loadEnvTexture()
{
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);  
	GLuint texture2;
	glGenTextures(1, &texture2);
	glActiveTexture(GL_TEXTURE1);
        glEnable(GL_TEXTURE_2D);
	
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT_OES);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_MIRRORED_REPEAT_OES);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
	
        NSString *fileNameString2 = [NSString stringWithFormat:@"%@",envTextureName];
        NSLog(@"fileNameString:%@", fileNameString2);
        NSString *texturePathString2 = [pathString stringByAppendingString:[NSString stringWithFormat:@"%@", fileNameString2]];
        NSLog(@"texturePathString:%@", texturePathString2);
        NSData *envTexData = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:[NSString stringWithFormat:@"%@", texturePathString2]]];

            UIImage *image2 = [[UIImage alloc] initWithData:envTexData];
            if (image2 == nil)
               return 0;
            
            GLuint width2 = CGImageGetWidth(image2.CGImage);
            GLuint height2 = CGImageGetHeight(image2.CGImage);
            CGColorSpaceRef colorSpace2 = CGColorSpaceCreateDeviceRGB();
            void *imageData2 = malloc( height2 * width2 * 4 );
            CGContextRef context2 = CGBitmapContextCreate( imageData2, width2, height2, 8, 4 * width2, colorSpace2, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big );
            CGColorSpaceRelease( colorSpace2 );
            CGContextClearRect( context2, CGRectMake( 0, 0, width2, height2 ) );
            CGContextDrawImage( context2, CGRectMake( 0, 0, width2, height2 ), image2.CGImage );
            
            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width2, height2, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData2);
            CGContextRelease(context2);
            
            free(imageData2);
            [image2 release];

    return texture2;
}

/* ------ I later call these functions in my UI loading code. (i know, bad place for that)*/
    [self loadShaders];
    loadTexture();
    loadEnvTexture();

/* ------ and also compile, link and load my vertex and fragment shaders before rendering*/
/* ------ here is the load shaders code */
- (BOOL)loadShaders
{
    GLuint vertShader, fragShader;
    NSString *vertShaderPathname, *fragShaderPathname;
    
    // Create shader program.
    program = glCreateProgram();
    
    // Create and compile vertex shader.
    vertShaderPathname = [[NSBundle mainBundle] pathForResource:@"Shader" ofType:@"vsh"];
    if (![self compileShader:&vertShader type:GL_VERTEX_SHADER file:vertShaderPathname])
    {
        NSLog(@"Failed to compile vertex shader");
        return FALSE;
    }
    
    // Create and compile fragment shader.
    fragShaderPathname = [[NSBundle mainBundle] pathForResource:@"Shader" ofType:@"fsh"];
    if (![self compileShader:&fragShader type:GL_FRAGMENT_SHADER file:fragShaderPathname])
    {
        NSLog(@"Failed to compile fragment shader");
        return FALSE;
    }
    
    // Attach vertex shader to program.
    glAttachShader(program, vertShader);
    
    // Attach fragment shader to program.
    glAttachShader(program, fragShader);
    
    // Bind attribute locations.
    // This needs to be done prior to linking.
    glBindAttribLocation(program, ATTRIB_VERTEX, "position");
    glBindAttribLocation(program, ATTRIB_NORMAL, "normal");
    glBindAttribLocation(program, ATTRIB_TEXCOORD, "texcoord");
    
    // Link program.
    if (![self linkProgram:program])
    {
        NSLog(@"Failed to link program: %d", program);
        
        if (vertShader)
        {
            glDeleteShader(vertShader);
            vertShader = 0;
        }
        if (fragShader)
        {
            glDeleteShader(fragShader);
            fragShader = 0;
        }
        if (program)
        {
            glDeleteProgram(program);
            program = 0;
        }
        
        return FALSE;
    }
    
    //tell it to use the shader programs
    glUseProgram(program);

    //Bind to textures
    glUniform1i(uniformTexture, 0);
    glUniform1i(uniformTexture2, 1);
    
    // Get uniform locations.
    uniforms[UNIFORM_MVP] = glGetUniformLocation(program, "mvp");
    uniforms[UNIFORM_COLOR] = glGetUniformLocation(program, "color");
    uniformTexture = glGetUniformLocation(program, "texture");
    uniformTexture2 = glGetUniformLocation(program, "envTexture");
    
    // Release vertex and fragment shaders.
    if (vertShader)
        glDeleteShader(vertShader);
    if (fragShader)
        glDeleteShader(fragShader);
    
    return TRUE;
}

/* ------ lastly, my fragment shader code*/
    varying mediump vec2 v_texcoord;
    uniform sampler2D texture;
    uniform sampler2D envTexture;

    void main()
    {
	gl_FragColor = texture2D(texture, v_texcoord);
        gl_FragColor += texture2D(envTexture, v_texcoord);
    }