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Improve handling of points on paths in getWinding()

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This commit is contained in:
iconexperience 2016-02-14 20:57:24 +01:00
parent 56dd636f22
commit e2eaf87fcb
1 changed files with 34 additions and 4 deletions
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38
src/path/PathItem.Boolean.js
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@ -305,7 +305,6 @@ PathItem.inject(new function() {
py = point.y,
windLeft = 0,
windRight = 0,
isOnCurve = false,
length = curves.length,
roots = [],
abs = Math.abs;
@ -341,7 +340,14 @@ PathItem.inject(new function() {
var xBefore = px - epsilon,
xAfter = px + epsilon,
prevWinding,
prevXEnd;
prevXEnd,
// Separately count the windings for points on curves.
windLeftOnCurve = 0,
windRightOnCurve = 0,
isOnCurve = false,
// Use the winding at the leftmost intersection to determine
// the orientation of the loop (clockwise / anti-clockwise).
leftIntersVal;
for (var i = 0; i < length; i++) {
var curve = curves[i],
winding = curve.winding,
@ -356,6 +362,10 @@ PathItem.inject(new function() {
// non-horizontal curve for the first curve in the loop.
prevWinding = curve.last.winding;
prevXEnd = curve.last.values[6];
// Reset the on curve flag and the leftmost intersection
// values for each loop.
isOnCurve = false;
leftIntersVal = null;
}
// Since the curves are monotonic in y direction, we can just
// compare the endpoints of the curve to determine if the ray
@ -396,16 +406,36 @@ PathItem.inject(new function() {
// the ray intersects a non-horizontal curve.
prevWinding = winding;
prevXEnd = values[6];
// Test if the point is on the horizontal curve
// Test if the point is on the horizontal curve.
} else if ((px - values[0]) * (px - values[6]) <= 0) {
isOnCurve = true;
}
}
// If we are at the end of a loop and the point was on a curve of the
// loop, we increment / decrement the on-curve winding numbers as if
// the point was inside the path.
if (i == length - 1 || curves[i + 1].last) {
if (isOnCurve) {
if (leftIntersVal && leftIntersVal[1] < 0) {
windLeftOnCurve -= 1;
windRightOnCurve += 1;
} else {
windLeftOnCurve += 1;
windRightOnCurve -= 1;
}
}
}
}
// Use the on-curve windings if no other intersections were
// found or if they canceled each other.
if (windLeft === 0 && windRight === 0) {
windLeft = windLeftOnCurve;
windRight = windRightOnCurve;
}
}
// If the point was on a monotonic curve, we are on the path by
// definition. In this case ensure that the winding is at least 1.
return Math.max(abs(windLeft), abs(windRight), isOnCurve ? 1 : 0);
return Math.max(abs(windLeft), abs(windRight));
}
function propagateWinding(segment, path1, path2, monoCurves, operator) {