24-03-2021, 08:56 AM
(This post was last modified: 24-03-2021, 01:49 PM by josemendez.)
Hi, just saw your video about bouncy fluid.
That's just due to the fluid's compressibility. The fluid compresses when you move the bucket up, then in de-compresses (bounces) once the movement stops.
Keep in mind that all fluids are compressible to some degree, and that this is a simulation, so it cannot be made completely incompressible. The strength of XPBD (the simulation method used by Obi) is precisely that remaining error in the simulation manifests itself as compliance (compressibility, in the case of fluids) instead of an unstable simulation.
To reduce compressibility, you can use more substeps and/or iterations. However this will make the simulation more expensive, so be careful. This manual page goes into details about how the simulation works and how iterations/substeps affect it: http://obi.virtualmethodstudio.com/tutor...gence.html
That's just due to the fluid's compressibility. The fluid compresses when you move the bucket up, then in de-compresses (bounces) once the movement stops.
Keep in mind that all fluids are compressible to some degree, and that this is a simulation, so it cannot be made completely incompressible. The strength of XPBD (the simulation method used by Obi) is precisely that remaining error in the simulation manifests itself as compliance (compressibility, in the case of fluids) instead of an unstable simulation.
To reduce compressibility, you can use more substeps and/or iterations. However this will make the simulation more expensive, so be careful. This manual page goes into details about how the simulation works and how iterations/substeps affect it: http://obi.virtualmethodstudio.com/tutor...gence.html
Quote:An insufficiently high iteration count will almost always manifest as some sort of unwanted softness/stretchiness, depending on which constraints could not be fully satisfied: Bouncy, compressible fluid if density constraints could not be met.