/**
 * @author WestLangley / http://github.com/WestLangley
 *
 * ACES Filmic Tone Mapping Shader by Stephen Hill
 * source: https://github.com/selfshadow/ltc_code/blob/master/webgl/shaders/ltc/ltc_blit.fs
 */



var ACESFilmicToneMappingShader = {

	uniforms: {

		'tDiffuse': { value: null },
		'exposure': { value: 1.0 }

	},

	vertexShader: [

		'varying vec2 vUv;',

		'void main() {',

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

		'}'

	].join( '\n' ),

	fragmentShader: [

		'#define saturate(a) clamp( a, 0.0, 1.0 )',

		'uniform sampler2D tDiffuse;',

		'uniform float exposure;',

		'varying vec2 vUv;',

		'vec3 RRTAndODTFit( vec3 v ) {',

		'	vec3 a = v * ( v + 0.0245786 ) - 0.000090537;',
		'	vec3 b = v * ( 0.983729 * v + 0.4329510 ) + 0.238081;',
		'	return a / b;',

		'}',

		'vec3 ACESFilmicToneMapping( vec3 color ) {',

		// sRGB => XYZ => D65_2_D60 => AP1 => RRT_SAT
		'	const mat3 ACESInputMat = mat3(',
		'		vec3( 0.59719, 0.07600, 0.02840 ),', // transposed from source
		'		vec3( 0.35458, 0.90834, 0.13383 ),',
		'		vec3( 0.04823, 0.01566, 0.83777 )',
		'	);',

		// ODT_SAT => XYZ => D60_2_D65 => sRGB
		'	const mat3 ACESOutputMat = mat3(',
		'		vec3(  1.60475, -0.10208, -0.00327 ),', // transposed from source
		'		vec3( -0.53108,  1.10813, -0.07276 ),',
		'		vec3( -0.07367, -0.00605,  1.07602 )',
		'	);',

		'	color = ACESInputMat * color;',

		// Apply RRT and ODT
		'	color = RRTAndODTFit( color );',

		'	color = ACESOutputMat * color;',

		// Clamp to [0, 1]
		'	return saturate( color );',

		'}',

		'void main() {',

		'	vec4 tex = texture2D( tDiffuse, vUv );',

		'	tex.rgb *= exposure;', // pre-exposed, outside of the tone mapping function

		'	gl_FragColor = vec4( ACESFilmicToneMapping( tex.rgb ), tex.a );',

		'}'

	].join( '\n' )

};

export { ACESFilmicToneMappingShader };
