scratchfoundation/paper.js
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Implement Curve#getParameter(point), untested.

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This commit is contained in:
Jürg Lehni 2011-07-06 23:15:32 +02:00
parent 56d62108cf
commit 9d2148245a
1 changed files with 43 additions and 1 deletions
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44
src/path/Curve.js
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@ -306,6 +306,17 @@ var Curve = this.Curve = Base.extend(/** @lends Curve# */{
return this._evaluate(parameter, 2);
},
/**
* @param {Point} point
* @return {Number}
*/
getParameter: function(point) {
var args = this.getValues();
if (point)
args.push(point.x, point.y);
return Curve.getParameter.apply(Curve, args);
},
getCrossings: function(point, prevSlope) {
// Implement the crossing number algorithm:
// http://en.wikipedia.org/wiki/Point_in_polygon
@ -330,7 +341,6 @@ var Curve = this.Curve = Base.extend(/** @lends Curve# */{
return crossings;
},
// TODO: getParameter(point, precision)
// TODO: getLocation
// TODO: getIntersections
// TODO: adjustThroughPoint
@ -504,6 +514,38 @@ var Curve = this.Curve = Base.extend(/** @lends Curve# */{
Numerical.TOLERANCE);
},
getParameter: function(p1x, p1y, c1x, c1y, c2x, c2y, p2x, p2y, x, y) {
var txs = Curve.solveCubic(p1x, c1x, c2x, p2x, x),
tys = Curve.solveCubic(p1y, c1y, c2y, p2y, y),
sx = txs === Infinity ? -1 : txs.length,
sy = tys === Infinity ? -1 : tys.length,
tx, ty;
// sx, sy == -1 means infinite solutions:
// Loop through all solutions for x and match with solutions for y,
// to see if we either have a matching pair, or infinite solutions
// for one or the other.
for (var cx = 0; sx == -1 || cx < sx;) {
if (sx == -1 || (tx = txs[cx++]) >= 0 && tx <= 1) {
for (var cy = 0; sy == -1 || cy < sy;) {
if (sy == -1 || (ty = tys[cy++]) >= 0 && ty <= 1) {
// Handle infinite solutions by assigning root of
// the other polynomial
if (sx == -1) tx = ty;
else if (sy == -1) ty = tx;
// Use average if we're within tolerance
if (Math.abs(tx - ty) < Numerical.TOLERANCE)
return (tx + ty) * 0.5;
}
}
// Avoid endless loops here: If sx is infinite and there was
// no fitting ty, there's no solution for this bezier
if (sx == -1)
break;
}
}
return null;
},
// TODO: Find better name
getPart: function(p1x, p1y, c1x, c1y, c2x, c2y, p2x, p2y, from, to) {
var curve = [p1x, p1y, c1x, c1y, c2x, c2y, p2x, p2y];