Cant close cracks in subdivide node

[andrewp2010]

Hey there! I am newer to houdini so this may be an obvious question, but I am currently working with a mesh that i would like to have part of it be a higher subdivided mesh so I can add parts of high detail to the mesh without having the entire thing be made of millions of polys. I was able to get that to work fine but after I subdivide the mesh using a subdivide node the option to close cracks is greyed out and it won't let me close the cracks that are created. Does anyone know why, and how can I use the close cracks function?

[raincole]

I stumbled upon this old question.

For future reference: closing crack is only supported by Houdini Catmull-Clark algorithm, not OpenSubdiv.

[animatrix]

For reference I implemented a modified OpenSubdiv Subdivide node that closes the gaps robustly. Just fusing is not robust FYI. With my implementation you have the speed of OpenSubdiv while getting better topology. Houdini Catmull Clark runs in exponential time if I am not wrong. That's why I had to use OpenSubdiv algorithm.

This was a big problem I had to solve when I was working on the Dark Phoenix crack setup that has incredibly high adaptive detail around the cracks (Level 13 subdivision). You can read more about it here:

https://vfxscience.com/2019/07/12/x-men-dark-phoenix/

This is also part of the VEX course I created in case anyone is wondering how to do it. It gets quite involved. Some more detail about the process and comments from the legendary Jeff Lait himself here:

https://www.sidefx.com/forum/topic/42633