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Some clean up in clipFatLine()

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This commit is contained in:
Jürg Lehni 2013-05-24 21:24:52 -07:00
parent 24f61c854a
commit 696887477a
1 changed files with 29 additions and 24 deletions
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53
fatline/Intersect.js
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@ -173,7 +173,7 @@ function getCurveIntersections(v1, v2, curve1, curve2, locations,
* fat-line
* @param {Array} v2 section of the second curve; we will clip this curve with
* the fat-line of v1
* @param {Object} range2 the parameter range of v2
* @param {Array} range2 the parameter range of v2
* @return {Number} 0: no Intersection, 1: one intersection, -1: more than one
* ntersection
*/
@ -202,28 +202,29 @@ function clipFatLine(v1, v2, range2) {
// checking whether the curves intersect with each other or not.
mindist = Math.min(dq0, dq1, dq2, dq3),
maxdist = Math.max(dq0, dq1, dq2, dq3);
// If the fatlines don't overlap, we have no intersections!
// If the fatlines don't overlap, we have no intersections!
if (dmin > maxdist || dmax < mindist)
return 0;
var tmp;
var Dt = getConvexHull(dq0, dq1, dq2, dq3),
tmp;
if (dq3 < dq0) {
tmp = dmin;
dmin = dmax;
dmax = tmp;
}
var Dt = getConvexHull(dq0, dq1, dq2, dq3);
// Calculate the convex hull for non-parametric bezier curve D(ti, di(t))
// Now we clip the convex hulls for D(ti, di(t)) with dmin and dmax
// for the coorresponding t values (tmin, tmax): Portions of curve v2 before
// tmin and after tmax can safely be clipped away
var tmaxdmin = -Infinity, ixd, ixdx, i, len, inv_m;
var tmin = Infinity, tmax = -Infinity, Dtl, dtlx1, dtly1, dtlx2, dtly2;
for (i = 0, len = Dt.length; i < len; i++) {
Dtl = Dt[i];
dtlx1 = Dtl[0];
dtly1 = Dtl[1];
dtlx2 = Dtl[2];
dtly2 = Dtl[3];
var tmaxdmin = -Infinity,
tmin = Infinity,
tmax = -Infinity;
for (var i = 0, l = Dt.length; i < l; i++) {
var Dtl = Dt[i],
dtlx1 = Dtl[0],
dtly1 = Dtl[1],
dtlx2 = Dtl[2],
dtly2 = Dtl[3];
if (dtly2 < dtly1) {
tmp = dtly2;
dtly2 = dtly1;
@ -232,24 +233,28 @@ function clipFatLine(v1, v2, range2) {
dtlx2 = dtlx1;
dtlx1 = tmp;
}
// we know that (dtlx2 - dtlx1) is never 0
inv_m = (dtly2 - dtly1) / (dtlx2 - dtlx1);
// We know that (dtlx2 - dtlx1) is never 0
var inv_m = (dtly2 - dtly1) / (dtlx2 - dtlx1);
if (dmin >= dtly1 && dmin <= dtly2) {
ixdx = dtlx1 + (dmin - dtly1) / inv_m;
if (ixdx < tmin) tmin = ixdx;
if (ixdx > tmaxdmin) tmaxdmin = ixdx;
var ixdx = dtlx1 + (dmin - dtly1) / inv_m;
if (ixdx < tmin)
tmin = ixdx;
if (ixdx > tmaxdmin)
tmaxdmin = ixdx;
}
if (dmax >= dtly1 && dmax <= dtly2) {
ixdx = dtlx1 + (dmax - dtly1) / inv_m;
if (ixdx > tmax) tmax = ixdx;
if (ixdx < tmin) tmin = 0;
var ixdx = dtlx1 + (dmax - dtly1) / inv_m;
if (ixdx > tmax)
tmax = ixdx;
if (ixdx < tmin)
tmin = 0;
}
}
// Return the parameter values for v2 for which we can be sure that the
// intersection with v1 lies within.
if (tmin !== Infinity && tmax !== -Infinity) {
var mindmin = Math.min(dmin, dmax);
var mindmax = Math.max(dmin, dmax);
var mindmin = Math.min(dmin, dmax),
mindmax = Math.max(dmin, dmax);
if (dq3 > mindmin && dq3 < mindmax)
tmax = 1;
if (dq0 > mindmin && dq0 < mindmax)
@ -258,8 +263,8 @@ function clipFatLine(v1, v2, range2) {
tmax = 1;
// tmin and tmax are within the range (0, 1). We need to project it to
// the original parameter range for v2.
var v2tmin = range2[0];
var tdiff = (range2[1] - v2tmin);
var v2tmin = range2[0],
tdiff = range2[1] - v2tmin;
range2[0] = v2tmin + tmin * tdiff;
range2[1] = v2tmin + tmax * tdiff;
// If the new parameter range fails to converge by atleast 20% of the