scratchfoundation/paper.js
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Rudimentary self-intersection calculation

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hkrish 2013-12-29 13:06:25 +01:00
parent 1bacbc32e9
commit a88d7f5eae
1 changed files with 62 additions and 0 deletions
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src/path/PathItem.js
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@ -84,6 +84,68 @@ var PathItem = Item.extend(/** @lends PathItem# */{
return locations;
},
getSelfIntersections: function(){
var locations = [],
locs = [],
curves = this.getCurves(),
length = curves.length - 1,
matrix = this._matrix.orNullIfIdentity(),
values = [],
curve1, values1, parts, i, j, k, ix, from, to, param, v1, v2,
EPSILON = /*#=*/ Numerical.EPSILON,
EPSILON1s = 1-EPSILON;
for (i = 0; i <= length; i++)
values[i] = curves[i].getValues(matrix);
for (i = 0; i <= length; i++) {
curve1 = curves[i];
values1 = values[i];
// First check for self-intersections within the same curve
from = curve1.getSegment1();
to = curve1.getSegment2();
v1 = from._handleOut;
v2 = to._handleIn;
// Check if extended handles of endpoints of this curve intersects
// each other. We cannot have a self intersection within this curve
// if they don't intersect due to convex-hull property.
ix = new paper.Line(from._point.subtract(v1), v1.multiply(2), true)
.intersect(new paper.Line(to._point.subtract(v2),
v2.multiply(2), true), false);
if (ix){
parts = paper.Curve.subdivide(values1);
locs.length = 0;
Curve.getIntersections(parts[0], parts[1], curve1, curve1, locs);
for (j = locs.length - 1; j >= 0; j--) {
ix = locs[0];
if (ix._parameter <= EPSILON1s) {
ix._parameter = ix._parameter * 0.5;
ix._parameter2 = 0.5 + ix._parameter2 * 0.5;
break;
}
}
if (j >= 0)
locations.push(ix);
}
// Check for intersections with other curves
for (j = i + 1; j <= length; j++){
// Avoid end point intersections on consecutive curves
if (j === i + 1 || (j === length && i === 0)) {
locs.length = 0;
Curve.getIntersections(values1, values[j], curve1,
curves[j], locs);
for (k = locs.length - 1; k >= 0; k--) {
param = locs[k].getParameter();
if (param < EPSILON1s && param > EPSILON)
locations.push(locs[k]);
}
} else {
paper.Curve.getIntersections(values1, values[j], curve1,
curves[j], locations);
}
}
}
return locations;
},
setPathData: function(data) {
// This is a very compact SVG Path Data parser that works both for Path
// and CompoundPath.