converting tris -> quads

[dayvbrown]

Hey hey,

So i'm sure at one point I had an answer for this but is there a simple way to get a surface made up of tris (in this case after a cookie) back into quads?

I've attached a file so you can see what i mean. The grid going in to the cookie is quads but comes out as nasty tris and for various reasons that is not what we want!

Cheers,

Dave.

untriangulate.hip

[Guest mantragora]

Turn off "Pre-Convex Geometry" on your Cookie SOP and save it as default preset. This option makes those ugly triangles.

[dayvbrown]

Turn off "Pre-Convex Geometry" on your Cookie SOP and save it as default preset. This option makes those ugly triangles.

nice one thanks,

but was thinking it as more of a general question outside of the use of cookies (this was just an example of a tri mesh I happened to have had lying around....)

Thanks again,

Dave.

[dpap]

Does anyone have an answer on this one?

 

Not cookie specific but generic triangulated geo into quads.

 

Both Maya and Softimage have a " Quadrangulate" command that most of times fixes things like that.

 

Is there something equivalent in Houdini?

[freaq]

as far as I know there is no built in functionality, and I must say it is hard to do,

I did some test trying to find the hypotheneuse of every triangle, seeing if they aling and if se deleting the edge between those triangles resulting in a quad.

but it's not perfect by any stretch. if anyone finds a proper quadrangulation method I'd be most interested.

[petz]

if you have a fairly simple geometry you could use the old tristrip-trick or just remove edges between pairs of triangles like freaq said.

quads.hip

[whodini]

if you subdivide triangulated geo with just 1 iteration, all faces will become quads. It's an old trick that modelers use.

[dpap]

Thank you for  answer Petz !

 

 

Cool post as always! 

 

 

if you have a fairly simple geometry 

 

yeeah... when the geo is complicated things get ugly... 

 

@Ryan  hmmm... yes but you get really weird topology after that .It works in some cases but raises the polycount.

 

 

Anyway.. Houdini definitely needs a Quadrangulate tool . Until then.. Softimage to the rescue.

 

Or maybe when the Remesh node gets more mature, it will transform into Zbrush's Zremesher  

Edited April 25, 2014 by dpap

[JuriBryan]

you can run a loop over each face and check how many points it has.
If its less then 4 you can subdivide only that face.
that way you dont increase the poly count to mush and you get rid of all the triangles.
just fuse them all back together afterwards

[ikoon]

@petz thank you for your script, helped me a lot. Please why is there 1.f in your code? I have never seen it:

angle_max = 1.f;

 

[petz]

it's just to make sure the number is float. doesn't make much sense in vex tbh. and you should probably use 1.0 instead. but well, old habits die hard ...