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Improve handling of exclude() operations.

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Determine wether to switch to other intersection or not based on tangents.

Closes #781 again.
This commit is contained in:
Jürg Lehni 2015-09-14 00:51:46 +02:00
parent b532c9cce2
commit e85586d0fe
1 changed files with 34 additions and 30 deletions
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64
src/path/PathItem.Boolean.js
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@ -152,7 +152,7 @@ PathItem.inject(new function() {
* @param {CurveLocation[]} intersections Array of CurveLocation objects
*/
function splitPath(intersections) {
if (window.report) {
if (window.reportIntersections) {
console.log('Intersections', intersections.length);
intersections.forEach(function(inter) {
if (inter._other)
@ -440,8 +440,6 @@ PathItem.inject(new function() {
function tracePaths(segments, monoCurves, operation) {
var segmentCount = 0;
var pathCount = 0;
var reportWindings = false && !window.silent;
var reportSegments = false && !window.silent;
var textAngle = 20;
var fontSize = 5 / paper.project.activeLayer.scaling.x;
@ -464,7 +462,7 @@ PathItem.inject(new function() {
}
function drawSegment(seg, text, index, color) {
if (!reportSegments)
if (!window.reportSegments)
return;
new Path.Circle({
center: seg.point,
@ -488,7 +486,7 @@ PathItem.inject(new function() {
for (var i = 0; i < (reportWindings ? segments.length : 0); i++) {
for (var i = 0; i < (window.reportWindings ? segments.length : 0); i++) {
var seg = segments[i];
path = seg._path,
id = path._id,
@ -509,6 +507,7 @@ PathItem.inject(new function() {
var paths = [],
operator = operators[operation],
epsilon = /*#=*/Numerical.EPSILON,
// Values for getTangentAt() that are almost 0 and 1.
// NOTE: Even though getTangentAt() supports 0 and 1 instead of
// tMin and tMax, we still need to use this instead, as other issues
@ -525,7 +524,7 @@ PathItem.inject(new function() {
startSeg = seg,
inter = seg._intersection,
otherSeg = inter && inter._segment,
startOtherSeg = otherSeg,
otherStartSeg = otherSeg,
added = false, // Whether a first segment as added already
dir = 1;
do {
@ -545,9 +544,17 @@ PathItem.inject(new function() {
// We need to handle exclusion separately and switch on
// every intersection that's part of the result.
if (operation === 'exclude') {
seg = otherSeg;
dir = 1;
drawSegment(seg, 'exclude', i, 'green');
// Look at the crossing tangents to decide whether
// to switch over or not.
var t1 = seg.getCurve().getTangentAt(tMin, true),
t2 = otherSeg.getCurve().getTangentAt(tMin, true);
if (Math.abs(t1.cross(t2)) > epsilon) {
seg = otherSeg;
drawSegment(seg, 'exclude:switch', i, 'green');
dir = 1;
} else {
drawSegment(seg, 'exclude:no cross', i, 'blue');
}
} else {
// Do not switch to the intersection as the segment
// is part of the boolean result.
@ -567,31 +574,28 @@ PathItem.inject(new function() {
dir = 1;
}
} else {
var c1 = seg.getCurve();
if (dir > 0)
c1 = c1.getPrevious();
var t1 = c1.getTangentAt(dir < 0 ? tMin : tMax, true),
var t = seg.getCurve().getTangentAt(tMin, true),
// Get both curves at the intersection
// (except the entry curves).
c4 = otherSeg.getCurve(),
c3 = c4.getPrevious(),
c2 = otherSeg.getCurve(),
c1 = c2.getPrevious(),
// Calculate their winding values and tangents.
t3 = c3.getTangentAt(tMax, true),
t4 = c4.getTangentAt(tMin, true),
t1 = c1.getTangentAt(tMax, true),
t2 = c2.getTangentAt(tMin, true),
// Cross product of the entry and exit tangent
// vectors at the intersection, will let us select
// the correct contour to traverse next.
w3 = t1.cross(t3),
w4 = t1.cross(t4);
if (Math.abs(w3 * w4) > /*#=*/Numerical.EPSILON) {
w1 = t.cross(t1),
w2 = t.cross(t2);
if (Math.abs(w1 * w2) > epsilon) {
// Do not attempt to switch contours if we aren't
// sure that there is a possible candidate.
var curve = w3 < w4 ? c3 : c4,
var curve = w1 < w2 ? c1 : c2,
nextCurve = operator(curve._segment1._winding)
? curve
: w3 < w4 ? c4 : c3,
: w1 < w2 ? c2 : c1,
nextSeg = nextCurve._segment1;
dir = nextCurve === c3 ? -1 : 1;
dir = nextCurve === c1 ? -1 : 1;
// If we didn't find a suitable direction for next
// contour to traverse, stay on the same contour.
if (nextSeg._visited && seg._path !== nextSeg._path
@ -601,7 +605,7 @@ PathItem.inject(new function() {
} else {
// Switch to the intersection segment.
seg = otherSeg;
// TODO:Why is this necessary, why not always 1?
// TODO: Find a case that actually requires this
if (nextSeg._visited)
dir = 1;
drawSegment(seg, 'switch', i, 'green');
@ -624,12 +628,12 @@ PathItem.inject(new function() {
seg = dir > 0 ? seg.getNext() : seg. getPrevious();
inter = seg && seg._intersection;
otherSeg = inter && inter._segment;
if (reportSegments) {
if (window.reportSegments) {
console.log(seg, seg && !seg._visited,
seg !== startSeg, seg !== startOtherSeg,
seg !== startSeg, seg !== otherStartSeg,
inter, seg && operator(seg._winding));
}
} while (seg && seg !== startSeg && seg !== startOtherSeg
} while (seg && seg !== startSeg && seg !== otherStartSeg
// Exclusion switches on each intersection, we need to look
// ahead & carry on if the other segment wasn't visited yet.
&& (!seg._visited || operation === 'exclude'
@ -637,10 +641,10 @@ PathItem.inject(new function() {
&& (inter || operator(seg._winding)));
// Finish with closing the paths if necessary, correctly linking up
// curves etc.
if (seg === startSeg || seg === startOtherSeg) {
if (seg === startSeg || seg === otherStartSeg) {
path.firstSegment.setHandleIn(seg._handleIn);
path.setClosed(true);
if (reportSegments) {
if (window.reportSegments) {
console.log('Boolean operation completed',
'#' + (pathCount + 1) + '.' +
(path ? path._segments.length + 1 : 1));
@ -660,7 +664,7 @@ PathItem.inject(new function() {
if (path && (path._segments.length > 4
|| !Numerical.isZero(path.getArea())))
paths.push(path);
if (reportSegments) {
if (window.reportSegments) {
pathCount++;
}
}