Revision: 73212
http://sourceforge.net/p/brlcad/code/73212
Author: starseeker
Date: 2019-05-30 21:18:03 +0000 (Thu, 30 May 2019)
Log Message:
-----------
Add some thoughts on the necessary pieces for CDT 'repair' logic to work
correctly
Modified Paths:
--------------
brlcad/trunk/src/libbrep/cdt.cpp
Modified: brlcad/trunk/src/libbrep/cdt.cpp
===================================================================
--- brlcad/trunk/src/libbrep/cdt.cpp 2019-05-30 12:36:25 UTC (rev 73211)
+++ brlcad/trunk/src/libbrep/cdt.cpp 2019-05-30 21:18:03 UTC (rev 73212)
@@ -25,6 +25,48 @@
*
*/
+/* TODO:
+ *
+ * Refactor checking routines (degen triangles, zero area triangles, normal
checks)
+ * into routines that can run per-face if possible.
+ *
+ * Need a process for how to modify edges and faces, and in what order. Need
to
+ * come up with heuristics for applying different "fixing" strategies:
+ *
+ * - remove problematic surface point from face tessellation
+ * - insert new point(s) at midpoints of edges of problem face
+ * - insert new point at the center of the problem face
+ * - split edge involved with problem face and retessellate both faces on that
edge
+ *
+ * Different strategies may be appropriate depending on the characteristics of
the
+ * "bad" triangle - for example, a triangle with all three brep normals nearly
perpendicular
+ * to the triangle normal and having only one non-edge point we should
probably try to
+ * handle by removing the surface point. On the other hand, if the angle is
not as
+ * perpendicular and the surface area is significant, we might want to add a
new point
+ * on the longest edge of the triangle (which might be a shared edge with
another face.)
+ *
+ * Also, consider whether to retessellate whole face or try to assemble
"local" set of
+ * faces involved, build bounding polygon and do new local tessellation.
Latter
+ * is a lot more work but might avoid re-introducing new problems elsewhere in
a
+ * mesh during a full re-CDT.
+ *
+ * Need to be able to introduce new edge points in specific subranges of an
edge.
+ *
+ * Try to come up with a system that is more systematic, rather than the
somewhat
+ * ad-hoc routines we have below. Will have to be iterative, and we can't
assume
+ * faces that were previously "clean" but which have to be reprocessed due to
a new
+ * edge point have remained clean.
+ *
+ * Remember there will be a variety of per-face containers that need to be
reset
+ * for this operation to work - may want to rework cdt state container to be
more
+ * per-face sets as opposed to maps-of-sets per face index, so we can wipe and
reset
+ * a face more easily.
+ *
+ * These are actually the same operations that will be needed for resolving
overlaps,
+ * so this is worth solving correctly.
+ */
+
+
#include "common.h"
#include "./cdt.h"
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