FAQ in daily usage

This page provides explanations/solutions for some commonly asked questions regarding the Ziva VFX product. These issues can be:

  • Bugs not caused by Ziva VFX, but are related to its use.

  • Bugs/error messages that are benign and have no effect on Ziva VFX use.

  • Features that appear to be bugs but are not.

  • Signs of a misconfiguration.

Solver Reports Error when Applying 1.0 Inertial Damping to a Standalone Tissue

Phenomenon:
Solver complains about invalid system when applying full inertial damping to a standalone tissue without attachments under gravity:

ERR| Creature timestep failed due to exception: Invalid input system

Cause:
Inertial damping reduces the inertia in the system; applying 1.0 inertial damping removes the inertia and makes it similar to a quasi-static problem where the solution is a static equilibrium state. However, a tissue that falls freely under gravity has no static equilibrium state, so the solver fails to find a solution.

Solution:
This use case is invalid and should be avoided. When 100% inertial damping is desired the tissue needs attachments to bones. Please check QuasiStatic notes under Integrators section.

Re-simulation May Explode after Switching Solvers

Phenomenon:
Simulation can explode when rewinding to the start frame then re-simulating the scene with a different solver selected.

Cause:
Creature information is not properly reset after rewinding to start frame when a new solver is created.

Solution:
Rebuild the scene via cmds.ziva(refresh=True) after rewinding to start frame if the solver explodes.

Ziva VFX version 2.2 plugin can’t load under Linux

Phenomenon:
Can’t load Linux plugin. Maya Script Editor outputs following error message complaining missing libcusparse, libcudart, or libcublas:

libcusparse.so.11: cannot open shared object file: No such file or directory

Cause:
The Maya module file doesn’t append shared file folder to the LD_LIBRARY_PATH environment variable, which causes this issue. We need to set the path manually before launching Maya.

Solution:
Refer to Linux Quick Installation for this extra installation step.

Save Ziva VFX Setup at Non-start Frame

Phenomenon:
The Maya Script Editor shows the following error message in isolation when opening a Ziva VFX setup:

ERR| Failure in creature solver. Creature is null.
ERR| zEmbedder zEmbedder1 - solver output creature is null

Cause:
The current frame does not match the start frame in the zSolverTransform node.

Solution:
Rewind to the start frame and save the setup.

Loading the Wrong Ziva VFX Maya Version

Phenomenon:
When manually loading a Ziva VFX plugin, the Maya Script Editor shows the following error message:

// Error: line 1: The specified procedure could not be found.

Cause:
The Ziva VFX Plugin version does not match the Maya version (for example, attempting to load the Maya 2019 Ziva plugin into Maya 2022 will cause this error).

Solution:
Make sure that the Ziva VFX and Maya versions match. A safer method is to load the plugin through the Maya Plugin Manager (which can be found at WindowsSettings/PreferencesPlug-in Manager).

Tissue object has no tet mesh

Phenomenon:
When pasting a copied Ziva rig, the Maya script editor shows the following error message:

ERR| failed to create creature due to exception: Tissue has no tet mesh. #

Cause:
This is a known bug caused by the Maya node evaluation order. The zSolver node is disabled and re-enabled during the paste operation. When the zSolver node is re-evaluated, the evaluation order is reversed, causing the tet mesh to be used before it is prepared.

Solution:
This problem corrects itself on a second pass, thus the error message can be ignored.