205 lines
3.7 KiB
JavaScript
205 lines
3.7 KiB
JavaScript
import {
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Color,
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LinearSRGBColorSpace,
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MathUtils
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} from 'three';
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class Lut {
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constructor( colormap, count = 32 ) {
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this.isLut = true;
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this.lut = [];
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this.map = [];
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this.n = 0;
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this.minV = 0;
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this.maxV = 1;
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this.setColorMap( colormap, count );
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}
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set( value ) {
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if ( value.isLut === true ) {
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this.copy( value );
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}
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return this;
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}
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setMin( min ) {
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this.minV = min;
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return this;
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}
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setMax( max ) {
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this.maxV = max;
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return this;
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}
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setColorMap( colormap, count = 32 ) {
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this.map = ColorMapKeywords[ colormap ] || ColorMapKeywords.rainbow;
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this.n = count;
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const step = 1.0 / this.n;
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const minColor = new Color();
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const maxColor = new Color();
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this.lut.length = 0;
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// sample at 0
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this.lut.push( new Color( this.map[ 0 ][ 1 ] ) );
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// sample at 1/n, ..., (n-1)/n
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for ( let i = 1; i < count; i ++ ) {
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const alpha = i * step;
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for ( let j = 0; j < this.map.length - 1; j ++ ) {
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if ( alpha > this.map[ j ][ 0 ] && alpha <= this.map[ j + 1 ][ 0 ] ) {
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const min = this.map[ j ][ 0 ];
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const max = this.map[ j + 1 ][ 0 ];
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minColor.setHex( this.map[ j ][ 1 ], LinearSRGBColorSpace );
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maxColor.setHex( this.map[ j + 1 ][ 1 ], LinearSRGBColorSpace );
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const color = new Color().lerpColors( minColor, maxColor, ( alpha - min ) / ( max - min ) );
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this.lut.push( color );
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}
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}
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}
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// sample at 1
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this.lut.push( new Color( this.map[ this.map.length - 1 ][ 1 ] ) );
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return this;
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}
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copy( lut ) {
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this.lut = lut.lut;
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this.map = lut.map;
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this.n = lut.n;
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this.minV = lut.minV;
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this.maxV = lut.maxV;
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return this;
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}
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getColor( alpha ) {
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alpha = MathUtils.clamp( alpha, this.minV, this.maxV );
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alpha = ( alpha - this.minV ) / ( this.maxV - this.minV );
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const colorPosition = Math.round( alpha * this.n );
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return this.lut[ colorPosition ];
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}
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addColorMap( name, arrayOfColors ) {
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ColorMapKeywords[ name ] = arrayOfColors;
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return this;
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}
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createCanvas() {
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const canvas = document.createElement( 'canvas' );
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canvas.width = 1;
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canvas.height = this.n;
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this.updateCanvas( canvas );
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return canvas;
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}
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updateCanvas( canvas ) {
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const ctx = canvas.getContext( '2d', { alpha: false } );
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const imageData = ctx.getImageData( 0, 0, 1, this.n );
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const data = imageData.data;
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let k = 0;
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const step = 1.0 / this.n;
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const minColor = new Color();
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const maxColor = new Color();
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const finalColor = new Color();
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for ( let i = 1; i >= 0; i -= step ) {
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for ( let j = this.map.length - 1; j >= 0; j -- ) {
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if ( i < this.map[ j ][ 0 ] && i >= this.map[ j - 1 ][ 0 ] ) {
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const min = this.map[ j - 1 ][ 0 ];
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const max = this.map[ j ][ 0 ];
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minColor.setHex( this.map[ j - 1 ][ 1 ], LinearSRGBColorSpace );
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maxColor.setHex( this.map[ j ][ 1 ], LinearSRGBColorSpace );
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finalColor.lerpColors( minColor, maxColor, ( i - min ) / ( max - min ) );
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data[ k * 4 ] = Math.round( finalColor.r * 255 );
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data[ k * 4 + 1 ] = Math.round( finalColor.g * 255 );
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data[ k * 4 + 2 ] = Math.round( finalColor.b * 255 );
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data[ k * 4 + 3 ] = 255;
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k += 1;
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}
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}
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}
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ctx.putImageData( imageData, 0, 0 );
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return canvas;
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}
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}
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const ColorMapKeywords = {
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'rainbow': [[ 0.0, 0x0000FF ], [ 0.2, 0x00FFFF ], [ 0.5, 0x00FF00 ], [ 0.8, 0xFFFF00 ], [ 1.0, 0xFF0000 ]],
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'cooltowarm': [[ 0.0, 0x3C4EC2 ], [ 0.2, 0x9BBCFF ], [ 0.5, 0xDCDCDC ], [ 0.8, 0xF6A385 ], [ 1.0, 0xB40426 ]],
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'blackbody': [[ 0.0, 0x000000 ], [ 0.2, 0x780000 ], [ 0.5, 0xE63200 ], [ 0.8, 0xFFFF00 ], [ 1.0, 0xFFFFFF ]],
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'grayscale': [[ 0.0, 0x000000 ], [ 0.2, 0x404040 ], [ 0.5, 0x7F7F80 ], [ 0.8, 0xBFBFBF ], [ 1.0, 0xFFFFFF ]]
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};
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export { Lut, ColorMapKeywords };
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