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Improve Curve#getCrossings() documentation and code.

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This commit is contained in:
Jürg Lehni 2013-04-25 11:08:50 -07:00
parent d7e075d316
commit eaa6e3bb6b
1 changed files with 15 additions and 15 deletions
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30
src/path/Curve.js
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@ -322,27 +322,27 @@ var Curve = this.Curve = Base.extend(/** @lends Curve# */{
if (t > -tolerance && t < 1 - tolerance) {
var pt = Curve.evaluate(vals, t, true, 0);
if (point.x < pt.x + tolerance) {
// Passing 1 for Curve.evaluate()'s type calculates tangents.
var tan = Curve.evaluate(vals, t, true, 1),
diff = abs(pt.x - point.x);
// Wee need to handle all kind of edge cases when points are
// on contours, ore rays are touching countours, do termine
// wether the corssings counts or not.
// Is the actual point is on the countour?
if (diff < tolerance) {
// Do not count the crossing if it is on the left
// hand side of the shape (tangent pointing upwards)
// since the ray will go out the other end and the
// point is on the contour, so inside.
// Passing 1 for Curve.evaluate() type calculates tangents
var tan = Curve.evaluate(vals, t, true, 1);
// Handle all kind of edge cases when points are on contours
// or rays are touching countours, to termine wether the
// crossing counts or not.
// See if the actual point is on the countour:
if (abs(pt.x - point.x) < tolerance) {
// Do not count the crossing if it is on the left hand
// side of the shape (tangent pointing upwards), since
// the ray will go out the other end, count as
// crossing there, and the point is on the contour, so
// to be considered inside.
var angle = tan.getAngle();
if (angle > -180 && angle < 0
// Handle special case where point is on a corner,
// in which case we only skip this crossing if both
// tangents have the same orientation (see below)
// in which case this crossing is skipped if both
// tangents have the same orientation.
&& (t > tolerance || changesOrientation(this, tan)))
continue;
} else {
// Skip touching stationary points
// Skip touching stationary points:
if (abs(tan.y) < tolerance
// Check derivate for stationary points. If root is
// close to 0 and not changing vertical orientation