scratchfoundation/paper.js
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Allow getWinding() to flip direction when on the path.

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Flipping will only occur when the encountered tangent is parallel to the ray. Relates to #1116
This commit is contained in:
Jürg Lehni 2016-07-22 16:50:39 +02:00
parent cbe41c536e
commit 0b11f9e2dc
1 changed files with 37 additions and 24 deletions
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39
src/path/PathItem.Boolean.js
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@ -362,7 +362,7 @@ PathItem.inject(new function() {
* well as an indication whether the point was situated on the contour * well as an indication whether the point was situated on the contour
* @private * @private
*/ */
function getWinding(point, curves, dir) { function getWinding(point, curves, dir, dontFlip) {
var epsilon = /*#=*/Numerical.WINDING_EPSILON, var epsilon = /*#=*/Numerical.WINDING_EPSILON,
// Determine the index of the abscissa and ordinate values in the // Determine the index of the abscissa and ordinate values in the
// curve values arrays, based on the direction: // curve values arrays, based on the direction:
@ -380,8 +380,10 @@ PathItem.inject(new function() {
onPathWinding = 0, onPathWinding = 0,
onPathCount = 0, onPathCount = 0,
onPath = false, onPath = false,
roots = [],
vPrev, vPrev,
vClose; vClose,
result;
function addWinding(v) { function addWinding(v) {
var o0 = v[io], var o0 = v[io],
@ -409,15 +411,15 @@ PathItem.inject(new function() {
// be added by adjacent curves. // be added by adjacent curves.
return vPrev; return vPrev;
} }
var roots = [], var t = null,
a = po === o0 ? a0 a = po === o0 ? a0
: po === o3 ? a3 : po === o3 ? a3
: paL > max(a0, a1, a2, a3) || paR < min(a0, a1, a2, a3) : paL > max(a0, a1, a2, a3) || paR < min(a0, a1, a2, a3)
? (a0 + a3) / 2 ? (a0 + a3) / 2
: Curve.solveCubic(v, io, po, roots, 0, 1) === 1 : Curve.solveCubic(v, io, po, roots, 0, 1) === 1
? Curve.getPoint(v, roots[0])[dir ? 'y' : 'x'] ? Curve.getPoint(v, t = roots[0])[dir ? 'y' : 'x']
: (a0 + a3) / 2; : (a0 + a3) / 2,
var winding = o0 > o3 ? 1 : -1, winding = o0 > o3 ? 1 : -1,
windingPrev = vPrev[io] > vPrev[io + 6] ? 1 : -1, windingPrev = vPrev[io] > vPrev[io + 6] ? 1 : -1,
a3Prev = vPrev[ia + 6]; a3Prev = vPrev[ia + 6];
if (po !== o0) { if (po !== o0) {
@ -452,6 +454,14 @@ PathItem.inject(new function() {
pathWindingL += winding; pathWindingL += winding;
} }
} }
if (onPath && !dontFlip) {
// If we're on the path, look at the tangent to determine if we
// should flip direction to determine a reliable winding number.
t = po === o0 ? 0 : po === o3 ? 1 : t;
result = t !== null
&& Curve.getTangent(v, t)[dir ? 'x' : 'y'] === 0
&& getWinding(point, curves, dir ? 0 : 1, true);
}
return v; return v;
} }
@ -473,13 +483,13 @@ PathItem.inject(new function() {
monoCurves = paL > max(a0, a1, a2, a3) || monoCurves = paL > max(a0, a1, a2, a3) ||
paR < min(a0, a1, a2, a3) paR < min(a0, a1, a2, a3)
? [v] : Curve.getMonoCurves(v, dir); ? [v] : Curve.getMonoCurves(v, dir);
for (var i = 0, l = monoCurves.length; i < l; i++) { for (var i = 0, l = monoCurves.length; !result && i < l; i++) {
vPrev = addWinding(monoCurves[i]); vPrev = addWinding(monoCurves[i]);
} }
} }
} }
for (var i = 0, l = curves.length; i < l; i++) { for (var i = 0, l = curves.length; !result && i < l; i++) {
var curve = curves[i], var curve = curves[i],
path = curve._path, path = curve._path,
v = curve.getValues(); v = curve.getValues();
@ -521,7 +531,7 @@ PathItem.inject(new function() {
handleCurve(v); handleCurve(v);
if (i + 1 === l || curves[i + 1]._path !== path) { if (!result && (i + 1 === l || curves[i + 1]._path !== path)) {
// We're at the last curve of the current (sub-)path. If a // We're at the last curve of the current (sub-)path. If a
// closing curve was calculated at the beginning of it, handle // closing curve was calculated at the beginning of it, handle
// it now to treat the path as closed: // it now to treat the path as closed:
@ -550,16 +560,17 @@ PathItem.inject(new function() {
onPath = false; onPath = false;
} }
} }
if (!result) {
if (!windingL && !windingR) { if (!windingL && !windingR) {
windingL = windingR = onPathWinding; windingL = windingR = onPathWinding;
} }
windingL = windingL && (2 - abs(windingL) % 2); windingL = windingL && (2 - abs(windingL) % 2);
windingR = windingR && (2 - abs(windingR) % 2); windingR = windingR && (2 - abs(windingR) % 2);
// Return both the calculated winding contribution, and also detect if // Return the calculated winding contribution and detect if we are
// we are on the contour of the area by comparing windingL and windingR. // on the contour of the area by comparing windingL and windingR.
// This is required when handling unite operations, where a winding // This is required when handling unite operations, where a winding
// contribution of 2 is not part of the result unless it's the contour: // number of 2 is not part of the result unless it's the contour:
return { result = {
winding: max(windingL, windingR), winding: max(windingL, windingR),
windingL: windingL, windingL: windingL,
windingR: windingR, windingR: windingR,
@ -567,6 +578,8 @@ PathItem.inject(new function() {
onPathCount: onPathCount onPathCount: onPathCount
}; };
} }
return result;
}
function propagateWinding(segment, path1, path2, curves, operator) { function propagateWinding(segment, path1, path2, curves, operator) {
// Here we try to determine the most likely winding number contribution // Here we try to determine the most likely winding number contribution