scratchfoundation/paper.js
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Shorten pre-calculations in Path#arcTo().

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This commit is contained in:
Jürg Lehni 2011-06-14 09:00:55 +01:00
parent f6b2672f08
commit f0c22bc1dc
1 changed files with 8 additions and 9 deletions
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17
src/path/Path.js
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@ -1745,6 +1745,7 @@ var Path = this.Path = PathItem.extend({
arcTo: function(to, clockwise) {
// Get the start point:
var current = getCurrentSegment(this),
from = current._point,
through;
if (typeof clockwise !== 'boolean') {
through = Point.read(arguments, 0, 1);
@ -1753,23 +1754,21 @@ var Path = this.Path = PathItem.extend({
to = Point.read(arguments, 0, 1);
if (clockwise === undefined)
clockwise = true;
var middle = current._point.add(to).divide(2),
step = middle.subtract(current._point);
through = clockwise
? middle.subtract(-step.y, step.x)
: middle.add(-step.y, step.x);
var middle = from.add(to).divide(2),
step = middle.subtract(from);
through = middle[clockwise ? 'subtract' : 'add'](-step.y, step.x);
}
var x1 = current._point._x, x2 = through.x, x3 = to.x,
y1 = current._point._y, y2 = through.y, y3 = to.y,
var x1 = from._x, x2 = through.x, x3 = to.x,
y1 = from._y, y2 = through.y, y3 = to.y,
f = x3 * x3 - x3 * x2 - x1 * x3 + x1 * x2 + y3 * y3 - y3 * y2
- y1 * y3 + y1 * y2,
g = x3 * y1 - x3 * y2 + x1 * y2 - x1 * y3 + x2 * y3 - x2 * y1,
m = g == 0 ? 0 : f / g,
e = x1 * x2 + y1 * y2 - m * (x1 * y2 - y1 * x2),
cx = (x1 + x2 - m * (y2 - y1)) / 2,
cy = (y1 + y2 - m * (x1 - x2)) / 2,
cx = (x1 + x2 + m * (y1 - y2)) / 2,
cy = (y1 + y2 + m * (x2 - x1)) / 2,
radius = Math.sqrt(cx * cx + cy * cy - e),
angle = Math.atan2(y1 - cy, x1 - cx),
middle = Math.atan2(y2 - cy, x2 - cx),