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Handle contour edge cases in Path#contains().

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Closes .
This commit is contained in:
Jürg Lehni 2013-04-25 11:03:49 -07:00
parent edfd8f53de
commit d7e075d316
3 changed files with 71 additions and 31 deletions
src/path
Curve.js

81
src/path/Curve.js
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@ -295,39 +295,62 @@ var Curve = this.Curve = Base.extend(/** @lends Curve# */{
var vals = this.getValues(),
count = Curve.solveCubic(vals, 1, point.y, roots),
crossings = 0,
tolerance = /*#=*/ Numerical.TOLERANCE;
tolerance = /*#=*/ Numerical.TOLERANCE,
abs = Math.abs;
// Checks the y-slope between the current curve and the previous for a
// change of orientation, when a solution is found at t == 0
function changesOrientation(curve, tangent) {
return Curve.evaluate(curve.getPrevious().getValues(), 1, true, 1).y
* tangent.y > 0;
}
// TODO: See if this speeds up code, or slows it down:
// var bounds = this.getBounds();
// if (point.y < bounds.getTop() || point.y > bounds.getBottom()
// || point.x > bounds.getRight())
// return 0;
if (count === -1) {
// Infinite solutions, so we have a horizontal curve.
// Find parameter through getParameterOf()
roots[0] = Curve.getParameterOf(vals, point.x, point.y);
count = roots[0] !== null ? 1 : 0;
}
for (var i = 0; i < count; i++) {
var t = roots[i];
if (t >= -tolerance && t < 1 - tolerance) {
if (t > -tolerance && t < 1 - tolerance) {
var pt = Curve.evaluate(vals, t, true, 0);
/*#*/ if (options.debug) {
console.log(t, point + '', pt + '');
new Path.Circle({
center: Curve.evaluate(vals, t, true, 0),
radius: 2,
strokeColor: 'red',
strokeWidth: 0.25
});
/*#*/ }
if (pt.x >= point.x - tolerance) {
if (point.x < pt.x + tolerance) {
// Passing 1 for Curve.evaluate()'s type calculates tangents.
var tangent = Curve.evaluate(vals, t, true, 1);
if (
// Skip touching stationary points (tips), but if the
// actual point is on one, do not skip this solution!
Math.abs(pt.x - point.x) > tolerance
&& (
// Check derivate for stationary points
Math.abs(tangent.y) < tolerance
// If root is close to 0 and not changing vertical
// orientation from the previous curve, do not count
// this root, as it's touching a corner.
|| t < tolerance
// Check the y-slope for a change of orientation
&& tangent.y * Curve.evaluate(
this.getPrevious().getValues(), 1, true, 1).y
< tolerance))
continue;
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.
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)
&& (t > tolerance || changesOrientation(this, tan)))
continue;
} else {
// 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
// from the previous curve, do not count this root,
// as it's touching a corner.
|| t < tolerance && !changesOrientation(this, tan))
continue;
}
crossings++;
}
}