scratchfoundation/paper.js
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Use chained variable definitions wherever we can to save space.

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This commit is contained in:
Jürg Lehni 2011-03-06 10:14:12 +00:00
parent 3a51acec88
commit 49e828ab9d
1 changed files with 49 additions and 47 deletions
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96
src/path/Path.js
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@ -49,26 +49,27 @@ var Path = this.Path = PathItem.extend({
// Calculates arclength of a cubic using adaptive simpson integration.
getCurveLength: function(goal) {
var seg0 = this._segments[0], seg1 = this._segments[1];
var z0 = seg0.point,
var seg0 = this._segments[0],
seg1 = this._segments[1],
z0 = seg0.point,
z1 = seg1.point,
c0 = z0.add(seg0.handleOut),
c1 = z1.add(seg1.handleIn);
// TODO: Check for straight lines and handle separately.
// Calculate the coefficients of a Bezier derivative, divided by 3.
var ax = 3 * (c0.x - c1.x) - z0.x + z1.x;
var bx = 2 * (z0.x + c1.x) - 4 * c0.x;
var cx = c0.x - z0.x;
var ax = 3 * (c0.x - c1.x) - z0.x + z1.x,
bx = 2 * (z0.x + c1.x) - 4 * c0.x,
cx = c0.x - z0.x,
var ay = 3 * (c0.y - c1.y) - z0.y + z1.y;
var by = 2 * (z0.y + c1.y) - 4 * c0.y;
var cy = c0.y - z0.y;
ay = 3 * (c0.y - c1.y) - z0.y + z1.y,
by = 2 * (z0.y + c1.y) - 4 * c0.y,
cy = c0.y - z0.y;
function ds(t) {
// Calculate quadratic equations of derivatives for x and y
var dx = (ax * t + bx) * t + cx;
var dy = (ay * t + by) * t + cy;
var dx = (ax * t + bx) * t + cx,
dy = (ay * t + by) * t + cy;
return Math.sqrt(dx * dx + dy * dy);
}
@ -210,9 +211,9 @@ var Path = this.Path = PathItem.extend({
// and the cubic is A B C D,
// B = E + 1/3 (A - E)
// C = E + 1/3 (D - E)
var current = this.currentSegment;
var x1 = current.point.x;
var y1 = current.point.y;
var current = this.currentSegment,
x1 = current.point.x,
y1 = current.point.y;
this.cubicCurveTo(
handle.add(current.point.subtract(handle).multiply(1/3)),
handle.add(to.subtract(handle).multiply(1/3)),
@ -257,29 +258,30 @@ var Path = this.Path = PathItem.extend({
: middle.add(-step.y, step.x);
}
var x1 = current.point.x, x2 = through.x, x3 = to.x;
var y1 = current.point.y, y2 = through.y, y3 = to.y;
var x1 = current.point.x, x2 = through.x, x3 = to.x,
y1 = current.point.y, y2 = through.y, y3 = to.y,
var f = x3 * x3 - x3 * x2 - x1 * x3 + x1 * x2 + y3 * y3 - y3 * y2
- y1 * y3 + y1 * y2;
var g = x3 * y1 - x3 * y2 + x1 * y2 - x1 * y3 + x2 * y3 - x2 * y1;
var m = g == 0 ? 0 : f / g;
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,
var c = (m * y2) - x2 - x1 - (m * y1);
var d = (m * x1) - y1 - y2 - (x2 * m);
var e = (x1 * x2) + (y1 * y2) - (m * x1 * y2) + (m * x2 * y1);
c = (m * y2) - x2 - x1 - (m * y1),
d = (m * x1) - y1 - y2 - (x2 * m),
e = (x1 * x2) + (y1 * y2) - (m * x1 * y2) + (m * x2 * y1),
var centerX = -c / 2;
var centerY = -d / 2;
var radius = Math.sqrt(centerX * centerX + centerY * centerY - e);
centerX = -c / 2,
centerY = -d / 2,
radius = Math.sqrt(centerX * centerX + centerY * centerY - e),
// Note: reversing the Y equations negates the angle to adjust
// for the upside down coordinate system.
var angle = Math.atan2(centerY - y1, x1 - centerX);
var middle = Math.atan2(centerY - y2, x2 - centerX);
var extent = Math.atan2(centerY - y3, x3 - centerX);
angle = Math.atan2(centerY - y1, x1 - centerX),
middle = Math.atan2(centerY - y2, x2 - centerX),
extent = Math.atan2(centerY - y3, x3 - centerX),
diff = middle - angle;
var diff = middle - angle;
if (diff < -Math.PI)
diff += Math.PI * 2;
else if (diff > Math.PI)
@ -293,8 +295,8 @@ var Path = this.Path = PathItem.extend({
else extent = -extent;
angle = -angle;
var ext = Math.abs(extent);
var arcSegs;
var ext = Math.abs(extent),
arcSegs;
if (ext >= 2 * Math.PI) arcSegs = 4;
else arcSegs = Math.ceil(ext * 2 / Math.PI);
@ -303,13 +305,13 @@ var Path = this.Path = PathItem.extend({
else if (inc < -2 * Math.PI) inc = -2 * Math.PI;
inc /= arcSegs;
var halfInc = inc / 2;
var z = 4 / 3 * Math.sin(halfInc) / (1 + Math.cos(halfInc));
var halfInc = inc / 2,
z = 4 / 3 * Math.sin(halfInc) / (1 + Math.cos(halfInc));
for (var i = 0; i <= arcSegs; i++) {
var relx = Math.cos(angle);
var rely = Math.sin(angle);
var pt = new Point(centerX + relx * radius,
var relx = Math.cos(angle),
rely = Math.sin(angle),
pt = new Point(centerX + relx * radius,
centerY + rely * radius);
var out;
if (i == arcSegs) out = null;
@ -362,10 +364,10 @@ var Path = this.Path = PathItem.extend({
var segments = this._segments;
var length = segments.length;
for (var i = 0; i < length; i++) {
var segment = segments[i];
var x = segment.point.x;
var y = segment.point.y;
var handleIn = segment.handleIn;
var segment = segments[i],
x = segment.point.x,
y = segment.point.y,
handleIn = segment.handleIn;
if (i == 0) {
ctx.moveTo(x, y);
} else {
@ -379,15 +381,15 @@ var Path = this.Path = PathItem.extend({
);
}
}
var handleOut = segment.handleOut;
var outX = handleOut.x + x;
var outY = handleOut.y + y;
var handleOut = segment.handleOut,
outX = handleOut.x + x,
outY = handleOut.y + y;
}
if (this.closed && length > 1) {
var segment = segments[0];
var x = segment.point.x;
var y = segment.point.y;
var handleIn = segment.handleIn;
var segment = segments[0],
x = segment.point.x,
y = segment.point.y,
handleIn = segment.handleIn;
ctx.bezierCurveTo(outX, outY, handleIn.x + x, handleIn.y + y, x, y);
ctx.closePath();
}