/**
 * @author miibond
 *
 * Full-screen tone-mapping shader based on http://www.graphics.cornell.edu/~jaf/publications/sig02_paper.pdf
 */

THREE.ToneMapShader = {

	uniforms: {

		"tDiffuse": { type: "t", value: null },
		"averageLuminance":  { type: "f", value: 1.0 },
		"luminanceMap":  { type: "t", value: null },
		"maxLuminance":  { type: "f", value: 16.0 },
		"middleGrey":  { type: "f", value: 0.6 }
	},

	vertexShader: [

		"varying vec2 vUv;",

		"void main() {",

			"vUv = uv;",
			"gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",

		"}"

	].join( "\n" ),

	fragmentShader: [

		"uniform sampler2D tDiffuse;",

		"varying vec2 vUv;",

		"uniform float middleGrey;",
		"uniform float maxLuminance;",
		"#ifdef ADAPTED_LUMINANCE",
			"uniform sampler2D luminanceMap;",
		"#else",
			"uniform float averageLuminance;",
		"#endif",
		
		"const vec3 LUM_CONVERT = vec3(0.299, 0.587, 0.114);",

		"vec3 ToneMap( vec3 vColor ) {",
			"#ifdef ADAPTED_LUMINANCE",
				// Get the calculated average luminance 
				"float fLumAvg = texture2D(luminanceMap, vec2(0.5, 0.5)).r;",
			"#else",
				"float fLumAvg = averageLuminance;",
			"#endif",
			
			// Calculate the luminance of the current pixel
			"float fLumPixel = dot(vColor, LUM_CONVERT);",

			// Apply the modified operator (Eq. 4)
			"float fLumScaled = (fLumPixel * middleGrey) / fLumAvg;",

			"float fLumCompressed = (fLumScaled * (1.0 + (fLumScaled / (maxLuminance * maxLuminance)))) / (1.0 + fLumScaled);",
			"return fLumCompressed * vColor;",
		"}",

		"void main() {",

			"vec4 texel = texture2D( tDiffuse, vUv );",
			
			"gl_FragColor = vec4( ToneMap( texel.xyz ), texel.w );",

		"}"

	].join( "\n" )

};
