Revision: 56185
http://sourceforge.net/p/brlcad/code/56185
Author: phoenixyjll
Date: 2013-07-23 05:31:28 +0000 (Tue, 23 Jul 2013)
Log Message:
-----------
Some clean up, and add comments to document the new features of SSI.
Modified Paths:
--------------
brlcad/trunk/src/libbrep/intersect.cpp
Modified: brlcad/trunk/src/libbrep/intersect.cpp
===================================================================
--- brlcad/trunk/src/libbrep/intersect.cpp 2013-07-23 04:57:31 UTC (rev
56184)
+++ brlcad/trunk/src/libbrep/intersect.cpp 2013-07-23 05:31:28 UTC (rev
56185)
@@ -1203,6 +1203,13 @@
check_domain(surfaceB_udomain, surfaceB->Domain(0), "surfaceB_udomain");
check_domain(surfaceB_vdomain, surfaceB->Domain(1), "surfaceB_vdomain");
+ Subcurve rootA;
+ Subsurface rootB;
+ if (!build_curve_root(curveA, curveA_domain, rootA))
+ return 0;
+ if (!build_surface_root(surfaceB, surfaceB_udomain, surfaceB_vdomain,
rootB))
+ return 0;
+
// We need ON_BrepFace for get_closest_point().
// This is used in point-surface intersections, in case we build the
// tree again and again.
@@ -1210,13 +1217,6 @@
if (!brep) return 0;
brlcad::SurfaceTree *tree = new brlcad::SurfaceTree(brep->Face(0), false,
MAX_PSI_DEPTH);
- Subcurve rootA;
- Subsurface rootB;
- if (!build_curve_root(curveA, curveA_domain, rootA))
- return 0;
- if (!build_surface_root(surfaceB, surfaceB_udomain, surfaceB_vdomain,
rootB))
- return 0;
-
// We adjust the tolerance from 3D scale to respective 2D scales.
double l = rootA.m_curve->BoundingBox().Diagonal().Length();
double dl = curveA_domain ? curveA_domain->Length() :
curveA->Domain().Length();
@@ -1635,6 +1635,7 @@
overlap2d->Append(NULL);
}
}
+
return x.Count() - original_count;
}
@@ -1660,10 +1661,21 @@
* points of the triangles (both in 3d space and two surfaces' UV
* space)
*
+ * - If an intersection point is accurate enough (within the tolerance),
+ * we append it to the list. Otherwise, we use Newton-Raphson iterations
+ * to solve an under-determined system to get an more accurate inter-
+ * section point.
+ *
* - Fit the intersection points into polyline curves, and then to NURBS
* curves. Points with distance less than max_dis are considered in
- * one curve.
+ * one curve. Points that cannot be fitted to a curve are regarded as
+ * single points.
*
+ * - Linear fittings and conic fittings are done to simplify the curves'
+ * representations.
+ *
+ * - Note: the overlap cases are handled at the beginning separately.
+ *
* See: Adarsh Krishnamurthy, Rahul Khardekar, Sara McMains, Kirk Haller,
* and Gershon Elber. 2008.
* Performing efficient NURBS modeling operations on the GPU.
@@ -1773,7 +1785,8 @@
double t[4];
int count = 0;
double t1, t2;
- // dpi*dpj < 0 - the corresponding points are on different sides
+ // dpi*dpj <= 0 - the corresponding points are on different sides,
+ // or at least one of them are on the intersection line.
// - the line segment between them are intersected by the plane-plane
// intersection line
if (dp1*dp2 < ON_ZERO_TOLERANCE) {
@@ -2249,14 +2262,18 @@
return 0;
// Generate brlcad::SurfaceTree() for point-surface intersections.
- ON_Brep *brep = surfA->BrepForm();
- if (!brep) return 0;
- brlcad::SurfaceTree *treeA = new brlcad::SurfaceTree(brep->Face(0), false,
MAX_PSI_DEPTH);
- delete brep;
- brep = surfB->BrepForm();
- if (!brep) return 0;
- brlcad::SurfaceTree *treeB = new brlcad::SurfaceTree(brep->Face(0), false,
MAX_PSI_DEPTH);
+ ON_Brep *brepA = surfA->BrepForm();
+ if (!brepA) return 0;
+ brlcad::SurfaceTree *treeA = new brlcad::SurfaceTree(brepA->Face(0),
false, MAX_PSI_DEPTH);
+ ON_Brep *brepB = surfB->BrepForm();
+ if (!brepB) {
+ delete brepA;
+ delete treeA;
+ return 0;
+ }
+ brlcad::SurfaceTree *treeB = new brlcad::SurfaceTree(brepB->Face(0),
false, MAX_PSI_DEPTH);
+
// We adjust the tolerance from 3D scale to respective 2D scales.
double intersection_tolerance_A = intersection_tolerance;
double intersection_tolerance_B = intersection_tolerance;
@@ -2293,6 +2310,7 @@
// (See ON_NurbsSurface::ConvertSpanToBezier()).
// So we actually don't need to generate the Bezier patches explicitly,
// and we can get the boundaries of them using IsoCurve() on knots.
+
ON_CurveArray overlaps, overlapA, overlapB;
for (int i = 0; i < 4; i++) {
const ON_Surface* surf1 = i >= 2 ? surfB : surfA;
@@ -2411,8 +2429,10 @@
overlaps[i] = overlapA[i] = overlapB[i] = NULL;
break;
}
+
if (j == overlaps.Count() || !overlaps[j] || !overlapA[j] ||
!overlapB[j])
continue;
+
// Merge the curves that link together.
if
(overlaps[i]->PointAtStart().DistanceTo(overlaps[j]->PointAtEnd()) <
intersection_tolerance
&&
overlapA[i]->PointAtStart().DistanceTo(overlapA[j]->PointAtEnd()) <
intersection_tolerance_A
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