[MOAB-dev] r4672 - MOAB/trunk

[tautges at mcs.anl.gov]

Author: tautges
Date: 2011-03-28 19:20:55 -0500 (Mon, 28 Mar 2011)
New Revision: 4672

Added:
   MOAB/trunk/README.IMESH
Log:
Initial cut at imesh readme.



Added: MOAB/trunk/README.IMESH
===================================================================
--- MOAB/trunk/README.IMESH	                        (rev 0)
+++ MOAB/trunk/README.IMESH	2011-03-29 00:20:55 UTC (rev 4672)
@@ -0,0 +1,59 @@
+MOAB iMesh Interface Implementation, iMesh v1.2
+===============================================
+
+1. Non-compliant iMesh functionality:
+
+1.1 Iterators for list-type entity sets: 
+
+The iMesh 1.2 specification requires that iterators over list-type entity sets be updated
+in response to membership changes in the set.  Specifically, if entities are added to or
+removed from the set, the spec requires that added entities be iterated without needing to
+reset the iterator, and that removed entities not be iterated.  MOAB will not support this
+capability in the iMesh 1.2 release.  Future support will depend on whether this can be
+implemented efficiently, without degrading performance for static mesh applications.
+
+1.2 No support for septahedron entities:
+
+MOAB does not support septahedron entities at this time (though such entities could be
+represented as general polyhedra).
+
+2. MOAB capabilities not accessible through iMesh:
+
+2.1 Dense tags: MOAB supports two kinds of tag storage: dense tags, where tag values are
+stored in sequence for sequences of contiguous entity handles; and sparse tags, which are
+stored in (entity handle, tag value) tuples.  iMesh does not support creation of a tag
+with a default value, nor does it have a mechanism for passing general options to the tag
+creation function.  Therefore, MOAB's iMesh implementation creates sparse tags by
+default.  Alternatives for specifying the tag creation type will be explored for future
+iMesh releases.
+
+2.2 Variable-length tags: MOAB supports a variable-length tag, where a tag value can have
+a different length for each entity to which it is assigned.  This functionality is not
+supported in iMesh.
+
+2.3 Direct access to tag data (tag_iterate functionality): MOAB 4.0.1 introduced the
+ability for applications to get direct access to tag storage for dense-type tags (see the
+tag_iterate function in src/moab/Interface.hpp).  This functionality is not supported in
+iMesh.
+
+2.4 Corner vs. all vertices in connectivity list: MOAB represents so-called "higher-order
+entities", e.g. quadratic tetrahedra, by allowing the connectivity list to be an
+application-specified size.  The connectivity array returned by MOAB's iMesh
+implementation will always be the total number of vertices, including any high-order
+vertices.  MOAB's interface allows applications to specify whether all or just corner
+vertices are requested.
+
+2.5 Retrieval of entity, set handles in order from list-type sets: MOAB uses the same