[MOAB-dev] r4344 - MOAB/trunk/src

[kraftche at cae.wisc.edu]

Author: kraftche
Date: 2010-12-09 14:24:52 -0600 (Thu, 09 Dec 2010)
New Revision: 4344

Modified:
   MOAB/trunk/src/AffineXform.cpp
   MOAB/trunk/src/AffineXform.hpp
Log:
add a few utility methods to AffineXform

Modified: MOAB/trunk/src/AffineXform.cpp
===================================================================
--- MOAB/trunk/src/AffineXform.cpp	2010-12-09 20:24:25 UTC (rev 4343)
+++ MOAB/trunk/src/AffineXform.cpp	2010-12-09 20:24:52 UTC (rev 4344)
@@ -24,10 +24,13 @@
 #include "moab/Interface.hpp"
 #include <assert.h>
 
-#ifndef TEST
 
 namespace moab {
 
+// Don't include tag-related stuff in test build because we don't
+// link to MOAB to test all other functionality.  
+#ifndef TEST
+
 const char* const AFFINE_XFORM_TAG_NAME = "AFFINE_TRANSFORM";
 
 ErrorCode AffineXform::get_tag( Tag& tag_out,
@@ -65,11 +68,49 @@
   
   return MB_SUCCESS;
 }
+
+#endif //TEST
+
+AffineXform AffineXform::rotation( const double* from_vec, const double* to_vec )
+{
+  CartVect from(from_vec);
+  CartVect to(to_vec);
+  CartVect a = from * to;
+  double len = a.length();
   
+  // If input vectors are not parallel (the normal case)
+  if (len >= std::numeric_limits<double>::epsilon()) {
+    from.normalize();
+    to.normalize();
+    return rotation( from % to, (from * to).length(), a/len );
+  }
+  
+  // Vectors are parallel:
+  //
+  // If vectors are in same direction then rotation is identity (no transform)
+  if (from % to >= 0.0)
+    return AffineXform(); 
+    
+  // Parallel vectors in opposite directions:
+  //
+  // NOTE:  This case is ill-defined.  There are infinitely
+  // many rotations that can align the two vectors.  The angle
+  // of rotation is 180 degrees, but the axis of rotation may