Find out which particle group to attach with the ObiParticleAttachment

[josemendez]

Thank you for the directions. I have another question, what is the best way to configure a soft body blueprint so it has different particle density in different regions? I know that you can manually remove particles after the auto-generation, but I don't know how to edit the cluster range. For example, if I want half of the soft body to have half as dense particles compare to the other half, if I set the cluster radius to fits the less dense half (which will be larger), it will work well with the less dense half, however the more dense half will have more cluster connections than desired. And if I set the cluster radius to be smaller to fit the denser half, then when I remove particles for the less dense half, the cluster radius won't be large enough for the less dense particles.

You can't use different resolutions for different parts of a softbody. The reason for this is that it would yield different physical behavior in different parts of the mesh due to different discretization of the space, which is pretty much always undesirable: zones with more particles would be more compliant (elastic) than zones with less particles.

If you really want to do this despite the drawbacks, keep in mind you can use completely different meshes for blueprint generation and rendering. See:
http://obi.virtualmethodstudio.com/manua...inner.html

So a relatively easy approach to do what you want would be authoring a mesh that's similar to the other you're rendering, but distribute vertex density differently throughout the mesh. Use this mesh for blueprint generation. Then use a small particle size when generating the blueprint, such that one particle is generated for each vertex in your mesh. This will take care of vertex density, however cluster radius will still be homogeneous throughout the mesh so certain zones will have a denser cluster network. This is actually a good thing as it reduces simulation dependency on discretization (regions with more particles are more densely interconnected, which compensates for decreased convergence).

If this doesn't do the job for you, you also have the option of deriving ObiSoftbodyBleuprintBase and creating your own blueprint generator. It's more work, but allows you to create particles and constraints any way you need.