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Declutter getConvexHull code.

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hkrish 2013-12-08 00:18:47 +01:00
parent baa189bb19
commit 834c8d17a9
1 changed files with 31 additions and 35 deletions
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src/path/Curve.js
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@ -1391,48 +1391,44 @@ new function() { // Scope for methods that require numerical integration
// Find signed distance of p1 and p2 from line [ p0, p3 ] // Find signed distance of p1 and p2 from line [ p0, p3 ]
getSignedDistance = Line.getSignedDistance, getSignedDistance = Line.getSignedDistance,
dist1 = getSignedDistance(0, dq0, 1, dq3, 1 / 3, dq1), dist1 = getSignedDistance(0, dq0, 1, dq3, 1 / 3, dq1),
dist2 = getSignedDistance(0, dq0, 1, dq3, 2 / 3, dq2); dist2 = getSignedDistance(0, dq0, 1, dq3, 2 / 3, dq2), hull;
// Check if p1 and p2 are on the same side of the line [ p0, p3 ] // Check if p1 and p2 are on the same side of the line [ p0, p3 ]
if (dist1 * dist2 < 0) { if (dist1 * dist2 < 0) {
// p1 and p2 lie on different sides of [ p0, p3 ]. The hull is a // p1 and p2 lie on different sides of [ p0, p3 ]. The hull is a
// quadrilateral and line [ p0, p3 ] is NOT part of the hull so we // quadrilateral and line [ p0, p3 ] is NOT part of the hull so we
// are pretty much done here. // are pretty much done here.
// return [ p0, p1, p3, p2 ]; // The top part includes p1,
return dist1 < 0 // we will reverse it later if that is not the case
// the top part includes p2 hull = [[p0, p1, p3], [p0, p2, p3]];
? [[p0, p2, p3], [p0, p1, p3]]
// the top part includes p1
: [[p0, p1, p3], [p0, p2, p3]];
}
// p1 and p2 lie on the same sides of [ p0, p3 ]. The hull can be
// a triangle or a quadrilateral and line [ p0, p3 ] is part of the
// hull. Check if the hull is a triangle or a quadrilateral.
var pmax, cross;
if (Math.abs(dist1) > Math.abs(dist2)) {
pmax = p1;
// apex is dq3 and the other apex point is dq0 vector
// dqapex->dqapex2 or base vector which is already part of the hull.
// cross = (vqa1a2X * vqa1MinY - vqa1a2Y * vqa1MinX)
// * (vqa1MaxX * vqa1MinY - vqa1MaxY * vqa1MinX)
cross = (dq3 - dq2 - (dq3 - dq0) / 3)
* (2 * (dq3 - dq2) - dq3 + dq1) / 3;
} else { } else {
pmax = p2; // p1 and p2 lie on the same sides of [ p0, p3 ]. The hull can be
// apex is dq0 in this case, and the other apex point is dq3 vector // a triangle or a quadrilateral and line [ p0, p3 ] is part of the
// dqapex->dqapex2 or base vector which is already part of the hull. // hull. Check if the hull is a triangle or a quadrilateral.
cross = (dq1 - dq0 + (dq0 - dq3) / 3) var pmax, cross;
* (-2 * (dq0 - dq1) + dq0 - dq2) / 3; if (Math.abs(dist1) > Math.abs(dist2)) {
pmax = p1;
// apex is dq3 and the other apex point is dq0 vector
// dqapex->dqapex2 or base vector which is already part of the hull.
cross = (dq3 - dq2 - (dq3 - dq0) / 3)
* (2 * (dq3 - dq2) - dq3 + dq1) / 3;
} else {
pmax = p2;
// apex is dq0 in this case, and the other apex point is dq3 vector
// dqapex->dqapex2 or base vector which is already part of the hull.
cross = (dq1 - dq0 + (dq0 - dq3) / 3)
* (-2 * (dq0 - dq1) + dq0 - dq2) / 3;
}
// Compare cross products of these vectors to determine if the point is
// in the triangle [ p3, pmax, p0 ], or if it is a quadrilateral.
hull = cross < 0
// p2 is inside the triangle, hull is a triangle.
? [[p0, pmax, p3], [p0, p3]]
// Convexhull is a quadrilateral and we need all lines in the
// correct order where line [ p0, p3 ] is part of the hull.
: [[p0, p1, p2, p3], [p0, p3]];
} }
// Compare cross products of these vectors to determine if the point is
// in the triangle [ p3, pmax, p0 ], or if it is a quadrilateral. return (dist1 < 0)? hull.reverse() : hull;
return cross < 0
// p2 is inside the triangle, hull is a triangle.
// ? [p0, pmax, p3]
? (dist1 < 0 ? [[p0, p3], [p0, pmax, p3]] : [[p0, pmax, p3], [p0, p3]])
// Convexhull is a quadrilateral and we need all lines in the
// correct order where line [ p0, p3 ] is part of the hull.
// : [ p0, p1, p2, p3 ];
: (dist1 < 0 ? [[p0, p3], [p0, p1, p2, p3]] : [[p0, p1, p2, p3], [p0, p3]]);
} }
/** /**