scratchfoundation/paper.js
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_tracePaths: Calculate correct entry&exit tangents.

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hkrish 2014-02-11 19:18:54 +01:00
parent 099f2d411e
commit 26ef85930d
1 changed files with 18 additions and 8 deletions
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26
src/path/PathItem.js
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@ -470,19 +470,24 @@ var PathItem = Item.extend(/** @lends PathItem# */{
// intersection, even when the curve[s] are linear.
function getEntryExitTangents(seg) {
var c2 = seg.getCurve(),
c1 = c2.getPrevious();
c1 = c2.getPrevious(), t = 1e-3;
// Avoid zero length curves
c1 = c1.getLength() === 0 ? c1.getPrevious() : c1;
c2 = c2.getLength() === 0 ? c2.getNext() : c2;
var v1 = c1.getValues(),
v2 = c2.getValues(),
pnt = seg.getPoint(),
ret = [seg.getHandleIn().normalize(),
seg.getHandleOut().normalize()];
if (ret[0].getLength() === 0)
ret[0] = new Point(pnt.x - v1[2], pnt.y - v1[3]);
if (ret[1].getLength() === 0)
ret[1] = new Point(pnt.x - v2[4], pnt.y - v2[5]);
ret = [seg.getHandleIn(), seg.getHandleOut()];
if (ret[0].getLength() === 0) {
ret[0] = new Point(pnt.x - v1[2], pnt.y - v1[3]).normalize();
} else {
ret[0] = Curve.evaluate(v1, 1-t, 1).normalize(-1);
}
if (ret[1].getLength() === 0) {
ret[1] = new Point(pnt.x - v2[4], pnt.y - v2[5]).normalize();
} else {
ret[1] = Curve.evaluate(v2, t, 1).normalize();
}
return ret;
}
// Choose a default operator which will return all contours
@ -535,6 +540,11 @@ var PathItem = Item.extend(/** @lends PathItem# */{
c4 = crvTan[1].c = c4.getLength() === 0 ? c4.getNext() : c4;
crvTan[0].t = entryExitTangents[0];
crvTan[1].t = entryExitTangents[1];
// DEBUG:--------------------------------------------------------
// annotateTan(seg.point, t1.normalize(20), "t1", true);
// annotateTan(seg.point, crvTan[0].t.normalize(20), "t2");
// annotateTan(seg.point, crvTan[1].t.normalize(20), "t3");
// DEBUG:--------------------------------------------------------
// cross product of the entry and exit tangent vectors at
// the intersection, will let us select the correct countour
// to traverse next.
@ -544,7 +554,7 @@ var PathItem = Item.extend(/** @lends PathItem# */{
}
// Do not attempt to switch contours if we aren't absolutely
// sure that there is a possible candidate.
if (crvTan[0].w * crvTan[1].w < 0) {
if (crvTan[0].w * crvTan[1].w !== 0) {
crvTan.sort(crvTanCompare);
j = 0;
do {