Revision: 73131
http://sourceforge.net/p/brlcad/code/73131
Author: starseeker
Date: 2019-05-22 14:17:48 +0000 (Wed, 22 May 2019)
Log Message:
-----------
Describe the various stages
Modified Paths:
--------------
brlcad/trunk/src/libbrep/cdt.cpp
Modified: brlcad/trunk/src/libbrep/cdt.cpp
===================================================================
--- brlcad/trunk/src/libbrep/cdt.cpp 2019-05-22 14:05:51 UTC (rev 73130)
+++ brlcad/trunk/src/libbrep/cdt.cpp 2019-05-22 14:17:48 UTC (rev 73131)
@@ -134,7 +134,9 @@
std::vector<p2t::Point*> polyline;
p2t::CDT* cdt = NULL;
- // first simply load loop point samples
+ // Use the edge curves and loops to generate an initial set of trim points.
+ // This generation is coordinated across shared faces to produce a
+ // watertight mesh.
for (int li = 0; li < loop_cnt; li++) {
double max_dist = 0.0;
const ON_BrepLoop *loop = face.Loop(li);
@@ -144,13 +146,13 @@
get_loop_sample_points(s_cdt, &brep_loop_points[li], face, loop,
max_dist, s_cdt->vert_pnts, s_cdt->vert_norms);
}
+ // Handle a variety of situations that complicate loop handling on closed
surfaces
std::list<std::map<double, ON_3dPoint *> *> bridgePoints;
if (s->IsClosed(0) || s->IsClosed(1)) {
PerformClosedSurfaceChecks(s_cdt, s, face, brep_loop_points,
BREP_SAME_POINT_TOLERANCE);
-
}
- // Find for this face the minimum and maximum edge polyline segment lengths
+ // Find for this face, find the minimum and maximum edge polyline segment
lengths
double max_edge_seg = 0.0;
double min_edge_seg = DBL_MAX;
for (int li = 0; li < loop_cnt; li++) {
@@ -171,10 +173,11 @@
}
}
}
+ // TODO - introduce these values into the tolerance structures...
bu_log("Face %d max_edge_seg: %f\n", face.m_face_index, max_edge_seg);
bu_log("Face %d min_edge_seg: %f\n", face.m_face_index, min_edge_seg);
- // process through loops building polygons.
+ // Process through loops, building Poly2Tri polygons for facetization.
bool outer = true;
for (int li = 0; li < loop_cnt; li++) {
int num_loop_points = brep_loop_points[li].Count();
@@ -230,12 +233,14 @@
return -1;
}
- // TODO - if we need to tie surface points to vertex normals (we do for
singular trims)
- // we will need more than just a point array back from on_surf_points - we
also need
- // the mapping to 3D normals and maybe points. We need to set the maps up
so the p2t
- // points will pull the correct normals when building a mesh
+ // Sample the surface, independent of the trimming curves, to get points
that
+ // will tie the mesh to the interior surface.
getSurfacePoints(s_cdt, face, on_surf_points);
+ // Strip out points from the surface that are on the trimming curves. Trim
+ // points require special handling for watertightness and introducing them
+ // from the surface also runs the risk of adding duplicate 2D points, which
+ // aren't allowed for facetization.
for (int i = 0; i < on_surf_points.Count(); i++) {
ON_SimpleArray<void*> results;
const ON_2dPoint *p = on_surf_points.At(i);
@@ -275,9 +280,11 @@
}
rt_trims.RemoveAll();
+ // All preliminary steps are complete, perform the triangulation using
+ // Poly2Tri
cdt->Triangulate(true, -1);
- /* Calculate any 3D points we don't already have */
+ /* Calculate any 3D points we don't already have from the loop processing
*/
std::vector<p2t::Triangle*> tris = cdt->GetTriangles();
for (size_t i = 0; i < tris.size(); i++) {
p2t::Triangle *t = tris[i];
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