( function () {

	/**
 * Depth-of-field shader using mipmaps
 * - from Matt Handley @applmak
 * - requires power-of-2 sized render target with enabled mipmaps
 */
	const DOFMipMapShader = {
		uniforms: {
			'tColor': {
				value: null
			},
			'tDepth': {
				value: null
			},
			'focus': {
				value: 1.0
			},
			'maxblur': {
				value: 1.0
			}
		},
		vertexShader:
  /* glsl */
  `

		varying vec2 vUv;

		void main() {

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

		}`,
		fragmentShader:
  /* glsl */
  `

		uniform float focus;
		uniform float maxblur;

		uniform sampler2D tColor;
		uniform sampler2D tDepth;

		varying vec2 vUv;

		void main() {

			vec4 depth = texture2D( tDepth, vUv );

			float factor = depth.x - focus;

			vec4 col = texture2D( tColor, vUv, 2.0 * maxblur * abs( focus - depth.x ) );

			gl_FragColor = col;
			gl_FragColor.a = 1.0;

		}`
	};

	THREE.DOFMipMapShader = DOFMipMapShader;

} )();