import THREE from 'three'
/**
 * @author alteredq / http://alteredqualia.com/
 *
 * Vignette shader
 * based on PaintEffect postprocess from ro.me
 * http://code.google.com/p/3-dreams-of-black/source/browse/deploy/js/effects/PaintEffect.js
 */

THREE.VignetteShader = {

  uniforms: {

    "tDiffuse": { type: "t", value: null },
    "offset":   { type: "f", value: 1.0 },
    "darkness": { type: "f", value: 1.0 }

  },

  vertexShader: [

    "varying vec2 vUv;",

    "void main() {",

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

    "}"

  ].join("\n"),

  fragmentShader: [

    "uniform float offset;",
    "uniform float darkness;",

    "uniform sampler2D tDiffuse;",

    "varying vec2 vUv;",

    "void main() {",

      // Eskil's vignette

      "vec4 texel = texture2D( tDiffuse, vUv );",
      "vec2 uv = ( vUv - vec2( 0.5 ) ) * vec2( offset );",
      "gl_FragColor = vec4( mix( texel.rgb, vec3( 1.0 - darkness ), dot( uv, uv ) ), texel.a );",

      /*
      // alternative version from glfx.js
      // this one makes more "dusty" look (as opposed to "burned")

      "vec4 color = texture2D( tDiffuse, vUv );",
      "float dist = distance( vUv, vec2( 0.5 ) );",
      "color.rgb *= smoothstep( 0.8, offset * 0.799, dist *( darkness + offset ) );",
      "gl_FragColor = color;",
      */

    "}"

  ].join("\n")

};

export default THREE.VignetteShader;