Blender Git Loki

-> Improved Triangle to Quad conversion

Alt-J behavior has been replaced by a port of the Tri2Quad python script
currently in CVS. This method has many advantages over the old behavior.
A simple illustration of how the new method is superior to the old can be
made by triangulating a suzzane and converting it back to quads.

http://www.umsl.edu/~gcbq44/t2q2a.jpg
http://www.umsl.edu/~gcbq44/t2q2b.jpg

The algorithm works by considering all possible triangle pairings and then
weighting them according to how appropriate it would be to join. These pairs
are then quick-sorted and those with the highest weighting factor are combined.
The function is quite fast even for dense meshes and usually involves no
noticeable wait-time for completion. For instance the following imported
model took less than 2 seconds to convert on my 1.3ghz PPC powerbook:

http://www.umsl.edu/~gcbq44/mimitri.jpg
http://www.umsl.edu/~gcbq44/mimiquad.jpg

It should be noted by the user that this method also discards face pairs
where the two triangles:

-do not share the same material
-do not share the same UV image (texface)
-do not share a compatible set of UV coordinates
-do not share a compatible set of vertex colors
-will form a concave quad or create a non-planar face

Additionally if the edge shared by the pair is marked 'sharp' the pair
will be discarded from the quicksort. In this way the user can gain great
control over the conversion process if they desire as this imported VRML
model of a sneaker illustrates:

http://www.umsl.edu/~gcbq44/t2qa.jpg
http://www.umsl.edu/~gcbq44/t2qb.jpg

For the future it would be nice if some of the options for the conversion
process, such as angle tolerance, could be made configurable in the UI.
However it is unclear at this time which options should be made configurable
and where to put them. Feedback on this is appreciated.

Special Thanks goes to Joe Eager for the two macros he contributed to this code
and to Campbell Barton for writing the script this was based on!