scratchfoundation/paper.js
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Change the way we determine the winding in getWinding(). Now the windings only get counted if the point is not on any of the y-monotonic curves. If the point is on a curve, the winding will be made odd at the very end.

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This commit is contained in:
iconexperience 2016-02-03 11:29:43 +01:00
parent 96d617a5ff
commit aed9d05bfc
1 changed files with 24 additions and 22 deletions
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46
src/path/PathItem.Boolean.js
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@ -349,7 +349,8 @@ PathItem.inject(new function() {
var xBefore = px - epsilon,
xAfter = px + epsilon,
prevWinding,
prevXEnd;
prevXEnd,
isOnCurve;
for (var i = 0; i < length; i++) {
var curve = curves[i],
winding = curve.winding,
@ -360,9 +361,9 @@ PathItem.inject(new function() {
// non-zero winding.
// Retrieve and use it here (See _getMonoCurve()).
if (curve.last) {
// Get the values of to the end x coordinate and winding of
// the last non-horizontal curve, which will be the previous
// non-horizontal curve for the first curve of the loop.
// Get the end x coordinate and winding of the last
// non-horizontal curve, which will be the previous
// non-horizontal curve for first curve in the loop.
prevWinding = curve.last.winding;
prevXEnd = curve.last.values[6];
}
@ -373,33 +374,33 @@ PathItem.inject(new function() {
// Horizontal curves with winding == 0 will be completely
// ignored.
if (winding && (py >= yStart && py <= yEnd
|| py >= yEnd && py <= yStart)) {
|| py >= yEnd && py <= yStart)) {
// Calculate the x value for the ray's intersection.
var x = py === yStart ? values[0]
: py === yEnd ? values[6]
: Curve.solveCubic(values, 1, py, roots, 0, 1) === 1
? Curve.getPoint(values, roots[0]).x
: null;
? Curve.getPoint(values, roots[0]).x
: null;
if (x != null) {
// If the point is between the curve's start point and
// the previous curve's end point, it must be on a
// horizontal curve inbetween.
var isOnHorizontal =
(py === yStart && (px - x) * (px - prevXEnd) < 0);
// Test if the point is on a y-monotonic curve
if ((x >= xBefore && x <= xAfter) || isOnHorizontal)
isOnCurve = true;
// Count the intersection of the ray with the
// monotonic curve if:
// - the crossing is not at the start of the curve
// - or the windings are opposite (intersect at a
// vertical extremum)
// - or the start of the current curve and the end
// of the prev curve are on opposite sides of px
var isWindingChange = winding === -prevWinding;
if (py !== yStart || isWindingChange
|| (x - px) * (prevXEnd - px) < 0) {
// y-monotonic curve if:
// - the crossing is not the start or end of the curve
// - or the crossing is at the start of the curve and
// the winding did not change between curves
if (py != yEnd
&& (py != yStart || winding === prevWinding)) {
if (x < xBefore) {
windLeft += winding;
} else if (x > xAfter) {
windRight += winding;
} else if (py === yStart && isWindingChange) {
// The point is a vertical extremum of the
// path.
++windLeft;
++windRight;
}
}
}
@ -410,7 +411,8 @@ PathItem.inject(new function() {
}
}
}
return Math.max(abs(windLeft), abs(windRight));
// If the point was on a monocurve, ensure that the winding is odd.
return Math.max(abs(windLeft), abs(windRight)) | (isOnCurve ? 1 : 0 );
}
function propagateWinding(segment, path1, path2, monoCurves, operator) {