Point Order

[Mcronin]

I have two objects with identical topolgies, but their point orders are different. Is there a way to transplant the point order from one to another? I ask because though both the topologies are the same, they have different shapes, and I want to morph one into the other with blend.

Alternatively, is there a way to blend objects that have different point orders?

[michael]

just reading the geometry.pdf....

looks like the Sort SOP might do this for you...

HTH

[Mcronin]

Spoke too soon this isn't working right...

[thekenny]

if your prim order is the same there should be a sop to do this in the proto install matchprimpoints.

-k

[anakin78z]

try sorting your points by vertex order.

[Mcronin]

Well thanks for the help guys but I don't think this is possible. The point order and primitive order is completely different though the objects contain identical numbers of primitives. The only thing I could think of was a VEX SOP that would find the closest point and replace it's number, but there's no way to guarantee it would grab the correct point. What I was trying to do was create an OTL that would allow you to bring a subdivision surface with Hierarchical edits into Houdini from Maya. It's stupid, but I thought of this before and someone asked on the mail list so I figured I'd give it a try.

Here's the basic idea. You take the subdivision surface in Maya and convert it to polygons at each level and export each level as an obj. Load each level in Houdini with a file SOP. Take level 0 and subdivide it. Morph this level 0 shape that has been subdivided into the same shape as the level 1 OBJ, repeat for level 2 and so on. When you're done, you'll have a network set up with all your hierarchical edits from Maya, and your UVs. capture, and whatever else will filter down properly through the network. You could even go back and edit and sculpt at the various levels if you wanted. I thought this would be especially cool because I don't think you can sculpt a subdivision surface in Maya.

Anyway, since the primitive and point orders are completely different, and I can't figure out a way to sort them identically on complex objects I can't use blend. The closest I came was using Ray, but it only gives a close approximation of the shape, not a match. I don't use Maya and it's not important to me, it's just something I wanted to see if I could work out. Thanks for the help.

[edward]

The MatchPrimPoints SOP (h6.1) was specifically to address that problem that if you took Houdini geometry, point edited in Maya, and then brought back, the point ordering would screw up while the primitive vertex ordering remained intact.

As for arbitrary topology, AttribTransfer (h6.1) is the way to go to transfer attributes from one model to another.

[FrankFirsching]

I don't think, that sculpting at the various levels will work, if you really work with a morph to the next level. I assume that you want to use the blend-SOP for this task, but it would morph the shape exactly into the level n OBJ and all your edits upwards in the chain would be lost. This means, that you will also need a special morph-SOP, which performs relative movement on the points. The problem here would be to find the right rest-positions, to which the offset could be calculated.

Even if this may sound so, I don't want to discourage you. I think, that many people would like to have the ability to bring hierarchical SubDs with the option to perform hierarchical edits into Houdini.

[Mcronin]

You're right. The best I can do with the Blend SOP is weight each of the inputs equally which isn't too good because I only get half the transform from each level. But... there just might be a way around that. It'll require a new SOP, and I have an idea.

I still can't get past this point order thing though. The vertex, point and primitive orders are all different. The closest I've been able to do is physucally rearrange the primitives into the proper order, but it destroys any existiing UVs in the process which is bad.