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Implement more intuitive version of clipConvexHull(), outlined in #570 by @iconexperience

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Code further shortened using a sub-routine.
This commit is contained in:
Jürg Lehni 2015-01-02 22:36:04 +01:00
parent 232739fae9
commit 477527f8ec
1 changed files with 26 additions and 38 deletions
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64
src/path/Curve.js
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@ -1264,48 +1264,36 @@ new function() { // Scope for methods that require numerical integration
}
/**
* Clips the convex-hull and returns [tMin, tMax] for the curve contained
* Clips the convex-hull and returns [tMin, tMax] for the curve contained.
*/
function clipConvexHull(hullTop, hullBottom, dMin, dMax) {
var tProxy,
tVal = null,
px, py,
qx, qy;
for (var i = 0, l = hullBottom.length - 1; i < l; i++) {
py = hullBottom[i][1];
qy = hullBottom[i + 1][1];
if (py < qy) {
tProxy = null;
} else if (qy <= dMax) {
px = hullBottom[i][0];
qx = hullBottom[i + 1][0];
tProxy = px + (dMax - py) * (qx - px) / (qy - py);
} else {
// Try the next chain
continue;
}
// We got a proxy-t;
break;
if (hullTop[0][1] < dMin) {
// Left of hull is below dMin, walk through the hull until it
// enters the region between dMin and dMax
return clipConvexHullPart(hullTop, true, dMin);
} else if (hullBottom[0][1] > dMax) {
// Left of hull is above dMax, walk through the hull until it
// enters the region between dMin and dMax
return clipConvexHullPart(hullBottom, false, dMax);
} else {
// Left of hull is between dMin and dMax, no clipping possible
return hullTop[0][0];
}
if (hullTop[0][1] <= dMax)
tProxy = hullTop[0][0];
for (var i = 0, l = hullTop.length - 1; i < l; i++) {
py = hullTop[i][1];
qy = hullTop[i + 1][1];
if (py >= dMin) {
tVal = tProxy;
} else if (py > qy) {
tVal = null;
} else if (qy >= dMin) {
px = hullTop[i][0];
qx = hullTop[i + 1][0];
tVal = px + (dMin - py) * (qx - px) / (qy - py);
} else {
continue;
}
break;
}
function clipConvexHullPart(part, top, threshold) {
var px = part[0][0],
py = part[0][1];
for (var i = 1, l = part.length; i < l; i++) {
var qx = part[i][0],
qy = part[i][1];
if (top ? qy >= threshold : qy <= threshold)
return px + (threshold - py) * (qx - px) / (qy - py);
px = qx;
py = qy;
}
return tVal;
// All points of hull are above / below the threshold
return null;
}
/*#*/ } // __options.fatlineClipping