Revision: 56405
http://sourceforge.net/p/brlcad/code/56405
Author: phoenixyjll
Date: 2013-08-01 05:50:03 +0000 (Thu, 01 Aug 2013)
Log Message:
-----------
Separate the Newton iterations of PCI out to a function.
Modified Paths:
--------------
brlcad/trunk/src/libbrep/intersect.cpp
Modified: brlcad/trunk/src/libbrep/intersect.cpp
===================================================================
--- brlcad/trunk/src/libbrep/intersect.cpp 2013-08-01 05:10:42 UTC (rev
56404)
+++ brlcad/trunk/src/libbrep/intersect.cpp 2013-08-01 05:50:03 UTC (rev
56405)
@@ -572,6 +572,44 @@
bool
+newton_pci(double& t, const ON_3dPoint& pointA, const ON_Curve& curveB, double
tolerance)
+{
+ ON_3dPoint closest_point = curveB.PointAt(t);
+ double dis = closest_point.DistanceTo(pointA);
+
+ // Use Newton-Raphson method with the starting point from linear
+ // approximation.
+ // It's similar to point projection (or point inversion, or get
+ // closest point on curve). We calculate the root of:
+ // (curve(t) - pointA) \dot tangent(t) = 0 (*)
+ // Then curve(t) may be the closest point on the curve to pointA.
+ //
+ // In some cases, the closest point (intersection point) is the
+ // endpoints of the curve, it does not satisfy (*), but that's
+ // OK because it already comes out with the linear approximation
+ // above.
+
+ double last_t = DBL_MAX;
+ int iterations = 0;
+ while (!ON_NearZero(last_t-t)
+ && dis > tolerance
+ && iterations++ < PCI_MAX_ITERATIONS) {
+ ON_3dVector tangent, s_deriv;
+ last_t = t;
+ curveB.Ev2Der(t, closest_point, tangent, s_deriv);
+ double F = ON_DotProduct(closest_point-pointA, tangent);
+ double derivF = ON_DotProduct(closest_point-pointA, s_deriv) +
ON_DotProduct(tangent, tangent);
+ if (!ON_NearZero(derivF))
+ t -= F/derivF;
+ dis = closest_point.DistanceTo(pointA);
+ }
+
+ closest_point = curveB.PointAt(t);
+ dis = closest_point.DistanceTo(pointA);
+ return dis <= tolerance;
+}
+
+bool
ON_Intersect(const ON_3dPoint& pointA,
const ON_Curve& curveB,
ON_ClassArray<ON_PX_EVENT>& x,
@@ -614,7 +652,7 @@
for (unsigned int i = 0; i < candidates.size(); i++) {
// Use linear approximation to get an estimated intersection point
ON_Line line(candidates[i]->m_curve->PointAtStart(),
candidates[i]->m_curve->PointAtEnd());
- double t, dis;
+ double t;
line.ClosestPointTo(pointA, &t);
// Make sure line_t belongs to [0, 1]
@@ -627,45 +665,15 @@
line_t = t;
double closest_point_t = candidates[i]->m_t.Min() +
candidates[i]->m_t.Length()*line_t;
- ON_3dPoint closest_point = curveB.PointAt(closest_point_t);
- dis = closest_point.DistanceTo(pointA);
- // Use Newton-Raphson method with the starting point from linear
- // approximation.
- // It's similar to point projection (or point inversion, or get
- // closest point on curve). We calculate the root of:
- // (curve(t) - pointA) \dot tangent(t) = 0 (*)
- // Then curve(t) may be the closest point on the curve to pointA.
- //
- // In some cases, the closest point (intersection point) is the
- // endpoints of the curve, it does not satisfy (*), but that's
- // OK because it already comes out with the linear approximation
- // above.
-
- double last_t = DBL_MAX;
- int iterations = 0;
- while (!ON_NearZero(last_t-closest_point_t)
- && dis > tolerance
- && iterations++ < PCI_MAX_ITERATIONS) {
- ON_3dVector tangent, s_deriv;
- last_t = closest_point_t;
- curveB.Ev2Der(closest_point_t, closest_point, tangent, s_deriv);
- double F = ON_DotProduct(closest_point-pointA, tangent);
- double derivF = ON_DotProduct(closest_point-pointA, s_deriv) +
ON_DotProduct(tangent, tangent);
- if (!ON_NearZero(derivF))
- closest_point_t -= F/derivF;
- dis = closest_point.DistanceTo(pointA);
- }
- closest_point = curveB.PointAt(closest_point_t);
-
- if (dis <= tolerance) {
+ if (newton_pci(closest_point_t, pointA, curveB, tolerance)) {
ON_PX_EVENT Event;
Event.m_type = ON_PX_EVENT::pcx_point;
Event.m_A = pointA;
- Event.m_B = closest_point;
+ Event.m_B = curveB.PointAt(closest_point_t);
Event.m_b[0] = closest_point_t;
Event.m_Mid = (pointA + Event.m_B) * 0.5;
- Event.m_radius = closest_point.DistanceTo(pointA) * 0.5;
+ Event.m_radius = Event.m_B.DistanceTo(pointA) * 0.5;
x.Append(Event);
return true;
}
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