function glconstants() {

	var constants = {
		POINTS: 0, ZERO: 0,
		LINES: 1, ONE: 1,
		LINE_LOOP: 2,
		LINE_STRIP: 3,
		TRIANGLES: 4,
		TRIANGLE_STRIP: 5,
		TRIANGLE_FAN: 6,
		DEPTH_BUFFER_BIT: 256,
		LESS: 513,
		NEVER: 512,
		EQUAL: 514,
		LEQUAL: 515,
		GREATER: 516,
		NOTEQUAL: 517,
		GEQUAL: 518,
		ALWAYS: 519,
		SRC_COLOR: 768,
		ONE_MINUS_SRC_COLOR: 769,
		SRC_ALPHA: 770,
		ONE_MINUS_SRC_ALPHA: 771,
		DST_ALPHA: 772,
		ONE_MINUS_DST_ALPHA: 773,
		DST_COLOR: 774,
		ONE_MINUS_DST_COLOR: 775,
		SRC_ALPHA_SATURATE: 776,
		STENCIL_BUFFER_BIT: 1024,
		FRONT: 1028,
		BACK: 1029,
		FRONT_AND_BACK: 1032,
		CW: 2304,
		CCW: 2305,
		CULL_FACE: 2884,
		DEPTH_TEST: 2929,
		STENCIL_TEST: 2960,
		BLEND: 3042,
		SCISSOR_TEST: 3089,
		UNPACK_ALIGNMENT: 3317,
		MAX_TEXTURE_SIZE: 3379,
		DEPTH24_STENCIL8: 35056,
		TEXTURE_2D: 3553,
		BYTE: 5120,
		UNSIGNED_BYTE: 5121,
		SHORT: 5122,
		UNSIGNED_INT: 5125,
		UNSIGNED_SHORT: 5123,
		INT: 5124,
		FLOAT: 5126,
		HALF_FLOAT: 5131,
		DEPTH_COMPONENT: 6402,
		RED: 6403,
		ALPHA: 6406,
		RGB: 6407,
		RGBA: 6408,
		LUMINANCE: 6409,
		LUMINANCE_ALPHA: 6410,
		VERSION: 7938,
		NEAREST: 9728,
		LINEAR: 9729,
		NEAREST_MIPMAP_NEAREST: 9984,
		LINEAR_MIPMAP_NEAREST: 9985,
		NEAREST_MIPMAP_LINEAR: 9986,
		LINEAR_MIPMAP_LINEAR: 9987,
		TEXTURE_MAG_FILTER: 10240,
		TEXTURE_MIN_FILTER: 10241,
		TEXTURE_WRAP_S: 10242,
		TEXTURE_WRAP_T: 10243,
		TEXTURE_WRAP_R: 32882,
		REPEAT: 10497,
		COLOR_BUFFER_BIT: 16384,
		FUNC_ADD: 32774,
		MIN: 32775,
		MAX: 32776,
		FUNC_SUBTRACT: 32778,
		FUNC_REVERSE_SUBTRACT: 32779,
		UNSIGNED_SHORT_4_4_4_4: 32819,
		UNSIGNED_SHORT_5_5_5_1: 32820,
		POLYGON_OFFSET_FILL: 32823,
		RGB8: 32849,
		RGBA4: 32854,
		RGBA8: 32856,
		TEXTURE_3D: 32879,
		CLAMP_TO_EDGE: 33071,
		DEPTH_COMPONENT16: 33189,
		DEPTH_STENCIL_ATTACHMENT: 33306,
		R8: 33321,
		R16F: 33325,
		R32F: 33326,
		UNSIGNED_SHORT_5_6_5: 33635,
		MIRRORED_REPEAT: 33648,
		TEXTURE0: 33984,
		DEPTH_STENCIL: 34041,
		UNSIGNED_INT_24_8: 34042,
		TEXTURE_CUBE_MAP: 34067,
		TEXTURE_CUBE_MAP_POSITIVE_X: 34069,
		MAX_CUBE_MAP_TEXTURE_SIZE: 34076,
		COMPRESSED_TEXTURE_FORMATS: 34467,
		RGBA32F: 34836,
		RGB32F: 34837,
		RGBA16F: 34842,
		RGB16F: 34843,
		MAX_VERTEX_ATTRIBS: 34921,
		MAX_TEXTURE_IMAGE_UNITS: 34930,
		ARRAY_BUFFER: 34962,
		ELEMENT_ARRAY_BUFFER: 34963,
		STATIC_DRAW: 35044,
		DYNAMIC_DRAW: 35048,
		VERTEX_SHADER: 35633,
		FRAGMENT_SHADER: 35632,
		MAX_VERTEX_TEXTURE_IMAGE_UNITS: 35660,
		MAX_COMBINED_TEXTURE_IMAGE_UNITS: 35661,
		COMPILE_STATUS: 35713,
		LINK_STATUS: 35714,
		VALIDATE_STATUS: 35715,
		ACTIVE_UNIFORMS: 35718,
		ACTIVE_ATTRIBUTES: 35721,
		IMPLEMENTATION_COLOR_READ_TYPE: 35738,
		IMPLEMENTATION_COLOR_READ_FORMAT: 35739,
		TEXTURE_2D_ARRAY: 35866,
		DEPTH_COMPONENT32F: 36012,
		COLOR_ATTACHMENT0: 36064,
		FRAMEBUFFER_COMPLETE: 36053,
		DEPTH_ATTACHMENT: 36096,
		FRAMEBUFFER: 36160,
		RENDERBUFFER: 36161,
		LOW_FLOAT: 36336,
		MEDIUM_FLOAT: 36337,
		HIGH_FLOAT: 36338,
		MAX_VERTEX_UNIFORM_VECTORS: 36347,
		MAX_VARYING_VECTORS: 36348,
		MAX_FRAGMENT_UNIFORM_VECTORS: 36349,
		UNPACK_FLIP_Y_WEBGL: 37440,
		UNPACK_PREMULTIPLY_ALPHA_WEBGL: 37441,
		MAX_SAMPLES: 36183,
		READ_FRAMEBUFFER: 36008,
		DRAW_FRAMEBUFFER: 36009
	};

	return {

		transform( code ) {

			code = code.replace( /_?gl\.([A-Z0-9_]+)/g, function ( match, p1 ) {

				if ( p1 in constants ) return constants[ p1 ];
				console.log( '* Unhandled GL Constant:', p1 );
				return match;

			} );

			return {
				code: code,
				map: { mappings: '' }
			};

		}

	};

}

function glsl() {

	return {

		transform( code, id ) {

			if ( /\.glsl.js$/.test( id ) === false ) return;

			code = code.replace( /\/\* glsl \*\/\`((.*|\n|\r\n)*)\`/, function ( match, p1 ) {

				return JSON.stringify(
					p1
						.trim()
						.replace( /\r/g, '' )
						.replace( /[ \t]*\/\/.*\n/g, '' ) // remove //
						.replace( /[ \t]*\/\*[\s\S]*?\*\//g, '' ) // remove /* */
						.replace( /\n{2,}/g, '\n' ) // # \n+ to \n
				);

			} );

			return {
				code: code,
				map: { mappings: '' }
			};

		}

	};

}

export default {
	input: 'src/Three.js',
	plugins: [
		glconstants(),
		glsl()
	],
	output: [
		{
			format: 'umd',
			name: 'THREE',
			file: 'build/three.js',
			indent: '\t'
		},
		{
			format: 'es',
			file: 'build/three.module.js',
			indent: '\t'
		}
	]
};