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161 lines
4.5 KiB
161 lines
4.5 KiB
import EdgeBase from './EdgeBase'
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/**
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* The Base Class for all Bezier edges. Bezier curves are used to model smooth
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* gradual curves in paths between nodes.
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*
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* @extends EdgeBase
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*/
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class BezierEdgeBase extends EdgeBase {
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/**
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* @param {Object} options
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* @param {Object} body
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* @param {Label} labelModule
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*/
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constructor(options, body, labelModule) {
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super(options, body, labelModule);
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}
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/**
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* This function uses binary search to look for the point where the bezier curve crosses the border of the node.
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*
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* @param {Node} nearNode
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* @param {CanvasRenderingContext2D} ctx
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* @param {Node} viaNode
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* @returns {*}
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* @private
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*/
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_findBorderPositionBezier(nearNode, ctx, viaNode = this._getViaCoordinates()) {
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var maxIterations = 10;
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var iteration = 0;
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var low = 0;
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var high = 1;
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var pos, angle, distanceToBorder, distanceToPoint, difference;
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var threshold = 0.2;
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var node = this.to;
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var from = false;
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if (nearNode.id === this.from.id) {
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node = this.from;
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from = true;
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}
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while (low <= high && iteration < maxIterations) {
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var middle = (low + high) * 0.5;
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pos = this.getPoint(middle, viaNode);
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angle = Math.atan2((node.y - pos.y), (node.x - pos.x));
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distanceToBorder = node.distanceToBorder(ctx, angle);
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distanceToPoint = Math.sqrt(Math.pow(pos.x - node.x, 2) + Math.pow(pos.y - node.y, 2));
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difference = distanceToBorder - distanceToPoint;
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if (Math.abs(difference) < threshold) {
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break; // found
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}
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else if (difference < 0) { // distance to nodes is larger than distance to border --> t needs to be bigger if we're looking at the to node.
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if (from === false) {
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low = middle;
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}
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else {
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high = middle;
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}
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}
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else {
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if (from === false) {
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high = middle;
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}
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else {
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low = middle;
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}
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}
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iteration++;
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}
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pos.t = middle;
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return pos;
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}
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/**
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* Calculate the distance between a point (x3,y3) and a line segment from
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* (x1,y1) to (x2,y2).
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* http://stackoverflow.com/questions/849211/shortest-distancae-between-a-point-and-a-line-segment
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* @param {number} x1 from x
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* @param {number} y1 from y
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* @param {number} x2 to x
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* @param {number} y2 to y
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* @param {number} x3 point to check x
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* @param {number} y3 point to check y
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* @param {Node} via
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* @returns {number}
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* @private
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*/
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_getDistanceToBezierEdge(x1, y1, x2, y2, x3, y3, via) { // x3,y3 is the point
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let minDistance = 1e9;
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let distance;
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let i, t, x, y;
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let lastX = x1;
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let lastY = y1;
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for (i = 1; i < 10; i++) {
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t = 0.1 * i;
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x = Math.pow(1 - t, 2) * x1 + (2 * t * (1 - t)) * via.x + Math.pow(t, 2) * x2;
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y = Math.pow(1 - t, 2) * y1 + (2 * t * (1 - t)) * via.y + Math.pow(t, 2) * y2;
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if (i > 0) {
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distance = this._getDistanceToLine(lastX, lastY, x, y, x3, y3);
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minDistance = distance < minDistance ? distance : minDistance;
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}
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lastX = x;
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lastY = y;
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}
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return minDistance;
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}
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/**
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* Draw a bezier curve between two nodes
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*
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* The method accepts zero, one or two control points.
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* Passing zero control points just draws a straight line
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*
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* @param {CanvasRenderingContext2D} ctx
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* @param {Object} values | options for shadow drawing
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* @param {Object|undefined} viaNode1 | first control point for curve drawing
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* @param {Object|undefined} viaNode2 | second control point for curve drawing
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*
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* @protected
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*/
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_bezierCurve(ctx, values, viaNode1, viaNode2) {
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var hasNode1 = (viaNode1 !== undefined && viaNode1.x !== undefined);
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var hasNode2 = (viaNode2 !== undefined && viaNode2.x !== undefined);
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ctx.beginPath();
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ctx.moveTo(this.fromPoint.x, this.fromPoint.y);
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if (hasNode1 && hasNode2) {
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ctx.bezierCurveTo(viaNode1.x, viaNode1.y, viaNode2.x, viaNode2.y, this.toPoint.x, this.toPoint.y);
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} else if (hasNode1) {
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ctx.quadraticCurveTo(viaNode1.x, viaNode1.y, this.toPoint.x, this.toPoint.y);
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} else {
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// fallback to normal straight edge
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ctx.lineTo(this.toPoint.x, this.toPoint.y);
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}
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// draw a background
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this.drawBackground(ctx, values);
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// draw shadow if enabled
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this.enableShadow(ctx, values);
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ctx.stroke();
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this.disableShadow(ctx, values);
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}
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/**
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*
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* @returns {*|{x, y}|{x: undefined, y: undefined}}
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*/
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getViaNode() {
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return this._getViaCoordinates();
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}
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}
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export default BezierEdgeBase;
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