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Switch to using arrays rather than objects for parameter ranges.

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This commit is contained in:
Jürg Lehni 2013-05-24 20:50:28 -07:00
parent 4a53767021
commit 1d1375915a
1 changed files with 37 additions and 42 deletions
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79
fatline/Intersect.js
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@ -65,28 +65,26 @@ function getCurveIntersections(v1, v2, curve1, curve2, locations, v1t, v2t,
if (recursion > MAX_RECURSION) if (recursion > MAX_RECURSION)
return; return;
// cache the original parameter range. // cache the original parameter range.
v1t = v1t || { t1: 0, t2: 1 }; v1t = v1t || [ 0, 1 ];
v2t = v2t || { t1: 0, t2: 1 }; v2t = v2t || [ 0, 1 ];
var _v1t = { t1: v1t.t1, t2: v1t.t2 }; var _v1t = v1t.slice();
var _v2t = { t1: v2t.t1, t2: v2t.t2 }; var _v2t = v2t.slice();
// Get the clipped parts from the original curve, to avoid cumulative errors // Get the clipped parts from the original curve, to avoid cumulative errors
var _v1 = Curve.getPart(v1, _v1t.t1, _v1t.t2); var _v1 = Curve.getPart(v1, _v1t[0], _v1t[1]);
var _v2 = Curve.getPart(v2, _v2t.t1, _v2t.t2); var _v2 = Curve.getPart(v2, _v2t[0], _v2t[1]);
// markCurve(_v1, '#f0f', true); // markCurve(_v1, '#f0f', true);
// markCurve(_v2, '#0ff', false); // markCurve(_v2, '#0ff', false);
var tmpt = { t1: null, t2: null }, var iteration = 0;
iteration = 0;
// Loop until both parameter range converge. We have to handle the // Loop until both parameter range converge. We have to handle the
// degenerate case seperately, where fat-line clipping can become // degenerate case seperately, where fat-line clipping can become
// numerically unstable when one of the curves has converged to a point and // numerically unstable when one of the curves has converged to a point and
// the other hasn't. // the other hasn't.
while (iteration++ < MAX_ITERATION while (iteration++ < MAX_ITERATION
&& (Math.abs(_v1t.t2 - _v1t.t1) > /*#=*/ Numerical.TOLERANCE && (Math.abs(_v1t[1] - _v1t[0]) > /*#=*/ Numerical.TOLERANCE
|| Math.abs(_v2t.t2 - _v2t.t1) > /*#=*/ Numerical.TOLERANCE)) { || Math.abs(_v2t[1] - _v2t[0]) > /*#=*/ Numerical.TOLERANCE)) {
// First we clip v2 with v1's fat-line // First we clip v2 with v1's fat-line
tmpt.t1 = _v2t.t1; var tmp = _v2t.slice();
tmpt.t2 = _v2t.t2; var intersects1 = clipFatLine(_v1, _v2, tmp),
var intersects1 = clipFatLine(_v1, _v2, tmpt),
intersects2 = 0; intersects2 = 0;
// Stop if there are no possible intersections // Stop if there are no possible intersections
if (intersects1 === 0) if (intersects1 === 0)
@ -94,23 +92,20 @@ function getCurveIntersections(v1, v2, curve1, curve2, locations, v1t, v2t,
if (intersects1 > 0) { if (intersects1 > 0) {
// Get the clipped parts from the original v2, to avoid cumulative // Get the clipped parts from the original v2, to avoid cumulative
// errors ...and reuse some objects. // errors ...and reuse some objects.
_v2t.t1 = tmpt.t1; _v2t = tmp;
_v2t.t2 = tmpt.t2; _v2 = Curve.getPart(v2, _v2t[0], _v2t[1]);
_v2 = Curve.getPart(v2, _v2t.t1, _v2t.t2);
// markCurve(_v2, '#0ff', false); // markCurve(_v2, '#0ff', false);
// Next we clip v1 with nuv2's fat-line // Next we clip v1 with nuv2's fat-line
tmpt.t1 = _v1t.t1; tmp = _v1t.slice();
tmpt.t2 = _v1t.t2; intersects2 = clipFatLine(_v2, _v1, tmp);
intersects2 = clipFatLine(_v2, _v1, tmpt);
// Stop if there are no possible intersections // Stop if there are no possible intersections
if (intersects2 === 0) if (intersects2 === 0)
break; break;
if (intersects1 > 0) { if (intersects1 > 0) {
// Get the clipped parts from the original v2, to avoid // Get the clipped parts from the original v2, to avoid
// cumulative errors // cumulative errors
_v1t.t1 = tmpt.t1; _v1t = tmp;
_v1t.t2 = tmpt.t2; _v1 = Curve.getPart(v1, _v1t[0], _v1t[1]);
_v1 = Curve.getPart(v1, _v1t.t1, _v1t.t2);
} }
// markCurve(_v1, '#f0f', true); // markCurve(_v1, '#f0f', true);
} }
@ -120,21 +115,21 @@ function getCurveIntersections(v1, v2, curve1, curve2, locations, v1t, v2t,
// Subdivide the curve which has converged the least from the // Subdivide the curve which has converged the least from the
// original range [0,1], which would be the curve with the largest // original range [0,1], which would be the curve with the largest
// parameter range after clipping // parameter range after clipping
if (_v1t.t2 - _v1t.t1 > _v2t.t2 - _v2t.t1) { if (_v1t[1] - _v1t[0] > _v2t[1] - _v2t[0]) {
// subdivide _v1 and recurse // subdivide _v1 and recurse
var t = (v1t.t1 + v1t.t2) / 2; var t = (v1t[0] + v1t[1]) / 2;
getCurveIntersections(v1, v2, curve1, curve2, locations, getCurveIntersections(v1, v2, curve1, curve2, locations,
{ t1: v1t.t1, t2: t }, v2t, recursion); [ v1t[0], t ], v2t, recursion);
getCurveIntersections(v1, v2, curve1, curve2, locations, getCurveIntersections(v1, v2, curve1, curve2, locations,
{ t1: t, t2: v1t.t2 }, v2t, recursion); [ t, v1t[1] ], v2t, recursion);
break; break;
} else { } else {
// subdivide _v2 and recurse // subdivide _v2 and recurse
var t = (v2t.t1 + v2t.t2) / 2; var t = (v2t[0] + v2t[1]) / 2;
getCurveIntersections(v1, v2, curve1, curve2, locations, v1t, getCurveIntersections(v1, v2, curve1, curve2, locations, v1t,
{ t1: v2t.t1, t2: t }, recursion); [ v2t[0], t ], recursion);
getCurveIntersections(v1, v2, curve1, curve2, locations, v1t, getCurveIntersections(v1, v2, curve1, curve2, locations, v1t,
{ t1: t, t2: v2t.t2 }, recursion); [ t, v2t[1] ], recursion);
break; break;
} }
} }
@ -149,19 +144,19 @@ function getCurveIntersections(v1, v2, curve1, curve2, locations, v1t, v2t,
// Check if one of the parameter range has converged completely to a // Check if one of the parameter range has converged completely to a
// point. Now things could get only worse if we iterate more for the // point. Now things could get only worse if we iterate more for the
// other curve to converge if it hasn't yet happened so. // other curve to converge if it hasn't yet happened so.
var v1Converged = (Math.abs(_v1t.t2 - _v1t.t1) < /*#=*/ Numerical.EPSILON), var v1Converged = (Math.abs(_v1t[1] - _v1t[0]) < /*#=*/ Numerical.EPSILON),
v2Converged = (Math.abs(_v2t.t2 - _v2t.t1) < /*#=*/ Numerical.EPSILON); v2Converged = (Math.abs(_v2t[1] - _v2t[0]) < /*#=*/ Numerical.EPSILON);
if (v1Converged || v2Converged) { if (v1Converged || v2Converged) {
addLocation(locations, curve1, null, v1Converged addLocation(locations, curve1, null, v1Converged
? curve1.getPointAt(_v1t.t1, true) ? curve1.getPointAt(_v1t[0], true)
: curve2.getPointAt(_v2t.t1, true), curve2); : curve2.getPointAt(_v2t[0], true), curve2);
break; break;
} }
if (Math.abs(_v1t.t2 - _v1t.t1) <= /*#=*/ Numerical.TOLERANCE if (Math.abs(_v1t[1] - _v1t[0]) <= /*#=*/ Numerical.TOLERANCE
&& Math.abs(_v2t.t2 - _v2t.t1) <= /*#=*/ Numerical.TOLERANCE) { && Math.abs(_v2t[1] - _v2t[0]) <= /*#=*/ Numerical.TOLERANCE) {
// Both parameter ranges have converged. // Both parameter ranges have converged.
addLocation(locations, curve1, _v1t.t1, addLocation(locations, curve1, _v1t[0],
curve1.getPointAt(_v1t.t1, true), curve2); curve1.getPointAt(_v1t[0], true), curve2);
break; break;
} }
// see if either or both of the curves are flat enough to be treated // see if either or both of the curves are flat enough to be treated
@ -273,14 +268,14 @@ function clipFatLine(v1, v2, v2t) {
tmax = 1; tmax = 1;
// tmin and tmax are within the range (0, 1). We need to project it to // tmin and tmax are within the range (0, 1). We need to project it to
// the original parameter range for v2. // the original parameter range for v2.
var v2tmin = v2t.t1; var v2tmin = v2t[0];
var tdiff = (v2t.t2 - v2tmin); var tdiff = (v2t[1] - v2tmin);
v2t.t1 = v2tmin + tmin * tdiff; v2t[0] = v2tmin + tmin * tdiff;
v2t.t2 = v2tmin + tmax * tdiff; v2t[1] = v2tmin + tmax * tdiff;
// If the new parameter range fails to converge by atleast 20% of the // If the new parameter range fails to converge by atleast 20% of the
// original range, possibly we have multiple intersections. We need to // original range, possibly we have multiple intersections. We need to
// subdivide one of the curves. // subdivide one of the curves.
if ((tdiff - (v2t.t2 - v2t.t1)) / tdiff >= 0.2) if ((tdiff - (v2t[1] - v2t[0])) / tdiff >= 0.2)
return 1; return 1;
} }
// TODO: Try checking with a perpendicular fatline to see if the curves // TODO: Try checking with a perpendicular fatline to see if the curves