scratchfoundation/paper.js
1
0
Fork 0
mirror of https://github.com/scratchfoundation/paper.js.git synced 2025-01-01 02:38:43 -05:00
Code Issues Projects Releases Packages Wiki Activity Actions

Merge pull request #938 from iconexperience/getWinding-simplification

Browse source 
Simplify getWindings() by using only the 'last' property to understand when a new loop starts.
This commit is contained in:
Jürg Lehni 2016-02-02 21:45:04 +01:00
commit 53269ab169
1 changed files with 55 additions and 61 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

116
src/path/PathItem.Boolean.js
View file

@ -348,69 +348,65 @@ PathItem.inject(new function() {
} else {
var xBefore = px - epsilon,
xAfter = px + epsilon,
start,
end = 0;
while (end < length) {
start = end;
// The first curve of a loop holds information about its length
// and the last curve with non-zero winding.
prevWinding,
prevXEnd;
for (var i = 0; i < length; i++) {
var curve = curves[i],
winding = curve.winding,
values = curve.values,
yStart = values[1],
yEnd = values[7];
// The first curve of a loop holds the last curve with
// non-zero winding.
// Retrieve and use it here (See _getMonoCurve()).
var curve = curves[start],
last = curve.last,
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.
prevWinding = last.winding,
prevXEnd = last.values[6];
end = start + curve.length;
for (var i = start; i < end; i++) {
var curve = curves[i],
winding = curve.winding,
values = curve.values,
yStart = values[1],
yEnd = values[7];
// Since the curves are monotone in y direction, we can just
// compare the endpoints of the curve to determine if the
// ray from query point along +-x direction will intersect
// the monotone curve.
// Horizontal curves with winding == 0 will be completely
// ignored.
if (winding && (py >= yStart && py <= yEnd
|| 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;
if (x != null) {
// 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) {
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;
}
prevWinding = curve.last.winding;
prevXEnd = curve.last.values[6];
}
// Since the curves are monotone in y direction, we can just
// compare the endpoints of the curve to determine if the
// ray from query point along +-x direction will intersect
// the monotone curve.
// Horizontal curves with winding == 0 will be completely
// ignored.
if (winding && (py >= yStart && py <= yEnd
|| 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;
if (x != null) {
// 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) {
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;
}
}
// Update previous winding and end coordinate whenever
// the ray intersects a non-horizontal curve.
prevWinding = winding;
prevXEnd = values[6];
}
// Update previous winding and end coordinate whenever
// the ray intersects a non-horizontal curve.
prevWinding = winding;
prevXEnd = values[6];
}
}
}
@ -976,11 +972,9 @@ Path.inject(/** @lends Path# */{
handleCurve([p1x, p1y, p1x, p1y, p2x, p2y, p2x, p2y]);
}
if (monoCurves.length > 0) {
// Add information about the loop length and the last curve with
// non-zero winding, as required in getWinding().
var first = monoCurves[0];
first.length = monoCurves.length;
first.last = last;
// Add information about the last curve with non-zero winding,
// as required in getWinding().
monoCurves[0].last = last;
}
}
return monoCurves;