scratchfoundation/paper.js
1
0
Fork 0
mirror of https://github.com/scratchfoundation/paper.js.git synced 2025-01-05 20:32:00 -05:00
Code Issues Projects Releases Packages Wiki Activity Actions

Small improvement in Path#arcTo() to reduce segment account in edge cases.

Browse source
This commit is contained in:
Jürg Lehni 2017-02-22 13:57:51 +01:00
parent d204175d39
commit ba2b18c7dc
1 changed files with 12 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

20
src/path/Path.js
View file

@ -2402,7 +2402,9 @@ new function() { // PostScript-style drawing commands
arcTo: function(/* to, clockwise | through, to arcTo: function(/* to, clockwise | through, to
| to, radius, rotation, clockwise, large */) { | to, radius, rotation, clockwise, large */) {
// Get the start point: // Get the start point:
var current = getCurrentSegment(this), var abs = Math.abs,
sqrt = Math.sqrt,
current = getCurrentSegment(this),
from = current._point, from = current._point,
to = Point.read(arguments), to = Point.read(arguments),
through, through,
@ -2441,7 +2443,6 @@ new function() { // PostScript-style drawing commands
pt = from.subtract(middle).rotate(-rotation), pt = from.subtract(middle).rotate(-rotation),
x = pt.x, x = pt.x,
y = pt.y, y = pt.y,
abs = Math.abs,
rx = abs(radius.width), rx = abs(radius.width),
ry = abs(radius.height), ry = abs(radius.height),
rxSq = rx * rx, rxSq = rx * rx,
@ -2449,7 +2450,7 @@ new function() { // PostScript-style drawing commands
xSq = x * x, xSq = x * x,
ySq = y * y; ySq = y * y;
// "...ensure radii are large enough" // "...ensure radii are large enough"
var factor = Math.sqrt(xSq / rxSq + ySq / rySq); var factor = sqrt(xSq / rxSq + ySq / rySq);
if (factor > 1) { if (factor > 1) {
rx *= factor; rx *= factor;
ry *= factor; ry *= factor;
@ -2466,8 +2467,7 @@ new function() { // PostScript-style drawing commands
center = new Point(rx * y / ry, -ry * x / rx) center = new Point(rx * y / ry, -ry * x / rx)
// "...where the + sign is chosen if fA != fS, // "...where the + sign is chosen if fA != fS,
// and the - sign is chosen if fA = fS." // and the - sign is chosen if fA = fS."
.multiply((large === clockwise ? -1 : 1) .multiply((large === clockwise ? -1 : 1) * sqrt(factor))
* Math.sqrt(factor))
.rotate(rotation).add(middle); .rotate(rotation).add(middle);
// Now create a matrix that maps the unit circle to the ellipse, // Now create a matrix that maps the unit circle to the ellipse,
// for easier construction below. // for easier construction below.
@ -2514,7 +2514,7 @@ new function() { // PostScript-style drawing commands
// If the center is lying on the line, we might have gotten // If the center is lying on the line, we might have gotten
// the wrong sign for extent above. Use the sign of the side // the wrong sign for extent above. Use the sign of the side
// of the through point. // of the through point.
extent = throughSide * Math.abs(extent); extent = throughSide * abs(extent);
} else if (throughSide === centerSide) { } else if (throughSide === centerSide) {
// If the center is on the same side of the line (from, to) // If the center is on the same side of the line (from, to)
// as the through point, we're extending bellow 180 degrees // as the through point, we're extending bellow 180 degrees
@ -2522,8 +2522,12 @@ new function() { // PostScript-style drawing commands
extent += extent < 0 ? 360 : -360; extent += extent < 0 ? 360 : -360;
} }
} }
var ext = Math.abs(extent), var epsilon = /*#=*/Numerical.EPSILON,
count = ext >= 360 ? 4 : Math.ceil(ext / 90), ext = abs(extent),
// Calculate the amount of segments required to approximate over
// `extend` degrees (extend / 90), but prevent ceil() from
// rounding up small imprecisions by subtracting epsilon first.
count = ext >= 360 ? 4 : Math.ceil((ext - epsilon) / 90),
inc = extent / count, inc = extent / count,
half = inc * Math.PI / 360, half = inc * Math.PI / 360,
z = 4 / 3 * Math.sin(half) / (1 + Math.cos(half)), z = 4 / 3 * Math.sin(half) / (1 + Math.cos(half)),