97 lines
1.5 KiB
JavaScript
97 lines
1.5 KiB
JavaScript
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/**
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* @author zz85 / http://www.lab4games.net/zz85/blog
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*/
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import { Earcut } from './Earcut.js';
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var ShapeUtils = {
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// calculate area of the contour polygon
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area: function ( contour ) {
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var n = contour.length;
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var a = 0.0;
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for ( var p = n - 1, q = 0; q < n; p = q ++ ) {
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a += contour[ p ].x * contour[ q ].y - contour[ q ].x * contour[ p ].y;
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}
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return a * 0.5;
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},
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isClockWise: function ( pts ) {
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return ShapeUtils.area( pts ) < 0;
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},
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triangulateShape: function ( contour, holes ) {
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var vertices = []; // flat array of vertices like [ x0,y0, x1,y1, x2,y2, ... ]
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var holeIndices = []; // array of hole indices
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var faces = []; // final array of vertex indices like [ [ a,b,d ], [ b,c,d ] ]
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removeDupEndPts( contour );
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addContour( vertices, contour );
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//
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var holeIndex = contour.length;
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holes.forEach( removeDupEndPts );
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for ( var i = 0; i < holes.length; i ++ ) {
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holeIndices.push( holeIndex );
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holeIndex += holes[ i ].length;
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addContour( vertices, holes[ i ] );
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}
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//
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var triangles = Earcut.triangulate( vertices, holeIndices );
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//
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for ( var i = 0; i < triangles.length; i += 3 ) {
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faces.push( triangles.slice( i, i + 3 ) );
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}
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return faces;
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}
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};
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function removeDupEndPts( points ) {
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var l = points.length;
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if ( l > 2 && points[ l - 1 ].equals( points[ 0 ] ) ) {
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points.pop();
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}
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}
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function addContour( vertices, contour ) {
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for ( var i = 0; i < contour.length; i ++ ) {
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vertices.push( contour[ i ].x );
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vertices.push( contour[ i ].y );
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}
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}
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export { ShapeUtils };
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