# Release Notes¶

## Version 1.8¶

### Functionality¶

• Add ‘Register License’ function to the ‘Ziva Menu’ for quicker and easier Ziva VFX license installation. This is the recommended way to install a license for the product. Learn how it works here: License Registration.

• Attachments with all-zero source weights will no longer affect on the simulation. Previously, it would prompt an error and stop the simulation from running.

• Creature modification can now take place before the simulation start frame. Modifications still have no effect until returning to the start frame, so this change is mostly a workflow convenience. This used to trigger an error in the command doing the modification.

• Program now searches the Ziva VFX Maya Module path for a license file, in addition to all previous search locations (the working directory, the plugin path, and the zivadyn_LICENSE environment variable) for easier license setup.

• Add Performance Tuning section to the docs, explaining how to tune/optimize a setup to run faster.

• Overhaul the backend logging system. This is mostly to simplify future development. There should be no visible changes, except possibly bugs in text formatting. As always, please report any such bugs.

### Bug Fixes¶

• Broken rendering bug on attachments with weights painted to values greater than one.

• Removing a subtissue would remove the connection in Maya, but not always remove it from the simulation.

• Improve retrieve operation performance when dealing with meshes.

• Fix some bugs on building and retrieving operations.

For the complete list of the ziva-vfx-utils release notes, please visit ziva-vfx-utils Release Notes.

## Version 1.7¶

### Functionality¶

• zRBFWarp can now warp NURBS surfaces and curves, in addition to meshes.

• Add zRestShape node and zRestShape command. These provide non-physical ways to manipulate the shape of a tissue for artistic intent.

• The Tutorials section of the docs has been totally rewritten.

### Node Changes¶

Node Change

Purpose

Manipulate the shape of a Tissue.

### Command Changes¶

Command

Purpose

Tools to create, edit, and use the zRestShape node.

### Bug Fixes¶

• Fixed sliding attachments sometimes attaching to the wrong spot. This would happen randomly if the sliding attachment lands exactly on an edge or vertex of the target mesh. This could result in noisy artifacts appearing in simulation results, which should be fixed now.

• Fixed a bug where providing both the shape node and transform node of a mesh as arguments to zBoneWarp causes errors in the output.

• Same as above for locator to zHarmonicWarp.

• Fixed a bug that sometimes causes a crash at the end of the zCache time window.

• Fixed a bug that sometimes causes incorrect dynamics with TR-BDF2 and BDF2 at the end of the zCache time window.

• Fixed a bug in caching sliding attachments.

• Fixed a TR-BDF2 and BDF2 contact handling bug.

## Version 1.619¶

### Functionality¶

• Add Maya 2019 support. Please note that Ziva simulations are not compatible with the new cached playback feature in Maya 2019, and cached playback will automatically be turned off if a Ziva Solver is enabled in a scene.

• General performance improvement of 0-20%, depending on the setup.

• Add a custom locator type for visualizing rivets in the viewport. The zRivetToBone command creates these nodes along with the rivet, so the rivets will be visible. Existing scenes with zRivetToBone nodes will not automatically have this visualization. Delete and re-create the rivet nodes to add the visualization.

### Attribute Changes¶

Node

Attribute Change

Purpose

zRivetToBone

For visualization.

### Bug Fixes¶

• Changing the input mesh topology after creating the warp (zRBFWarp, zHarmonicWarp or zBoneWarp) sometimes (rarely) causes a crash.

## Version 1.6¶

### Functionality¶

• Add new Ziva Anatomy Transfer (ZAT) deformers for transferring creature geometry from a source creature onto a new creature.

• Add Python scripts that wrap common zBuilder functionality to transfer Ziva rigs from (parts of a) source creature onto a new creature.

• Add a new zRivetToBone deformer and command. Use this to drive zLineOfAction curves. Some built-in Maya techniques for doing this create cycles in the dependency graph, which can make simulation results incorrect. This node and its command should not introduce cycles. Furthermore, having this node as a standardized approach for driving zLineOfAction curves simplifies scripting and improves script portability.

• Add new options to “Ziva” menu for erasing all Ziva rigs in a selected Ziva solver, or from the entire Maya scene.

• Improve simulation robustness (better low-level deformable object numerics).

• Improve performance in general, about 15-20% on typical anatomical setups.

### Node Changes¶

Node Change

Purpose

Harmonic warp deformer for internal anatomy (tissues, fascias, Maya joints, locators).

Bone warp deformer. Keeps the bones straight based on a painted landmark map.

Radial Basis Function (RBF) warp deformer. Useful, e.g., for geometry outside of the creature (eyelashes, hair, etc.).

Deformer for attaching curve CVs to bones meshes.

### Command Changes¶

Command

Purpose

Creates and binds a zHarmonicWarp deformer.

Creates and binds a zBoneWarp deformer.

Creates and binds a zRBFWarp deformer.

Creates and binds a zRivetToBone deformer.

### Bug Fixes¶

• Fix crash when closing scenes with subtissues. This crash happens unpredictably, about 1 in 15 times, only in scenes using subtissues and only when there’s more than one subtissue per parent.

• Fix sliding attachments sometimes getting stuck on triangle edges and not sliding smoothly.

## Version 1.5¶

### Functionality¶

• Support multiple integration schemes: implicit backward Euler, BDF2, TR-BDF2, quasi-static. Add zSolver.integrator to select the integrator.

• Merge the zFindIntersections and zFindSelfIntersect commands into zFindIntersections.

• Improved verbosity-selection interface. “ziva -vb” has been revised to accept verbosity levels from 0 (only show errors) to 3 (show operation and progress).

• Deprecated hard attachments and hard contact. They continue to work, but are hidden from the Maya UI, and may be removed in future versions. New designs should use soft attachments and contact.

### Attribute Changes¶

Node

Attribute Change

Purpose

zSolver

Remove quasiStatic

Quasi-static solver is now specified using the attribute zSolver.integrator.

zAttachment

Deprecate (hide) isHard

Seldom used feature and there is an excellent alternative (isHard=off).

zTissue

Deprecate (hide) hardContact

Seldom used feature and there is an excellent alternative (hardContact=off).

zCloth

Deprecate (hide) hardContact

Seldom used feature and there is an excellent alternative (hardContact=off).

Note

If you open a file saved with version v1.4 (or earlier) that contains a zSolver whose quasiStatic attribute has been set to true, you will see the following Maya error message:

// Error: line 0: The zSolver 'zSolver1Shape' has no 'qua' attribute.
// Error: line 0: Node "zSolver1Shape" has no attribute "qua".


This error occurs because the zSolver.quasiStatic attribute has been deleted in v1.5. The solver will not use the quasi-static mode, unless you specify it using the zSolver.integrator attribute. Even if you do this, the error message will persist. You can get rid of the error message by saving the scene using the v1.5 plugin. When the scene is re-opened, the error message will no longer appear.

### Command Changes¶

Command

Purpose

Query the current verbosity level.

Excludes intersections between different meshes from the query – thus finding only self intersections.

Remove zFindSelfIntersection

Replaced by zFindIntersections -xo.

### Bug Fixes¶

• Calling “ziva -vb” with no arguments results in undefined behavior. Now, “ziva -vb” always requires an argument. There is now a separate command “ziva -vbq” to query the current verbosity level.

## Version 1.4 hotfix 1¶

### Bug Fixes¶

• Fixed a bug where Maya Fields did not evaluate correctly if the solver transform changed after the first frame.

• When zSolver.maxNewtonIterations is greater than 1, the dynamics were often under-damped. The dynamics are correctly damped now, which will result in some simulations appearing more damped than before. To recover similar results to previous versions, decrease zSolver.stiffnessDamping and zSolver.massDamping – possibly to the new default values: 0.001 and 0.0 respectively. This was fixed in 1.4’s initial release, but missed in the release notes.

• Fixed a bug where a “Solver has encountered instabilities” message persisted even after rewinding to the first frame.

• Fixed a bug where adding a new body to the scene could affect the simulation results of existing, unconnected bodies.

• Fixed a bug where zBuilder would sometimes not record the field and zFieldAdaptor nodes.

• Fixed a bug where zBuilder would sometimes re-order zMaterial nodes.

## Version 1.4¶

### Functionality¶

• Add Rest Scale to make tissues shrink (or grow) equally in all directions (previously already available for cloth).

• Add Muscle Growth to grow or shrink tissues perpendicularly to muscle fibers, making characters more muscular or leaner.

• Add Pressure to apply an external pressure force to tissues (previously already available for cloth).

• Add Surface Tension to apply a surface tension force to tissues and cloth.

• Maya Fields can now be used to add external forces to Ziva bodies.

• Decreased the default value of zSolver.stiffnessDamping. This makes simulations more lively by default, but sometimes also less stable.

• In Ziva VFX v1.1 to v1.3, the attributes zMaterial.pressure and zMaterial.restScale applied only to cloth bodies, but now they also apply to tissue bodies. In existing scenes made with v1.1 to v1.3, these attributes already exist on tissue material nodes, but will not show up in the channel box. Correct this with the following MEL script:

select ls -type zMaterial
setAttr .restScale -channelBox true
setAttr .pressure -channelBox true


### Node Changes¶

Node Change

Purpose

Adaptor node for connecting Maya fields to Tissue and Cloth objects (to add external forces)

### Attribute Changes¶

Node

Attribute Change

Purpose

zTissue

To allow connection to Maya fields (via zFieldAdaptor)

zTissue

Envelope for pressure force

zTissue

Envelope for rest scale

zTissue

Envelope for surface tension

zCloth

To allow connection to Maya fields (via zFieldAdaptor)

zCloth

Envelope for pressure force (e.g., for stable runups)

zCloth

Envelope for rest scale (e.g., for stable runups)

zCloth

Envelope for surface tension (e.g., for stable runups)

zMaterial

To set the amount of surface tension

zFiber

Turn muscle growth on/off

zFiber

Amount of muscle growth

zFiber

Drive muscle growth via line of action

### Command Changes¶

Command

Purpose

To connect an existing Maya field to a Tissue/Cloth object (for external forces)

### Bug Fixes¶

• Display an error when a zGeo.iNeutralMesh has a mesh with zero vertices or faces. This happens when a missing Alembic is connected directly to this plug.

## Version 1.3¶

### Functionality¶

• Improved multi-solver workflows:

• All commands can now accept scene object inputs by name. If no scene objects are given by name, the currently selected objects are used, as before.

• Ex: ziva -t pSphere1; converts pSphere1 into a tissue.

• Ex: zFindSelfIntersections myMesh1; finds self-intersections in myMesh1.

• Ex: zCache -l "myCache.zCache" zSolver1; loads a simulation cache into zSolver1.

• Ex: zSelectVerticesByProximity -r 0.5 myMesh1 myMesh2; finds vertices on myMesh1 that are within 0.5 units of myMesh2.

• Fibers and attachments draw grey when their envelope attributes are set to zero, to show that they are effectively disabled.

• Attachment rendering fades to transparent as its weightmap fades to black.

• zSelectVerticesByProximity has been renamed to zFindVerticesByProximity.

• zFindIntersections and zFindSelfIntersections can both work with any number of meshes, instead of just 2 or 1 respectively.

• zFindIntersections can optionally also find self-intersections.

• The zFindIntersections, zFindSelfIntersections, and zFindVerticesByProximity MEL commands now return selection strings instead of changing the current selection.

• The behavior of the corresponding Ziva Tools menu items has not changed, and will still set the current selection.

• To achieve the old behavior when writing MEL, you can call, for example: select zFindIntersections;.

• Reduce default collision stiffness on zTissue and zCloth nodes to reduce jitter and improve stability with default settings.

• The zCopyMesh command has been deprecated, and will be removed in a future release.

### Bug Fixes¶

• Attribute zFiber.envelope also affects excitation due to zLineOfAction. Consequently, if zFiber.envelope is zero, that fiber will not contract.

• Tissue tetrahedralization will no longer happen while zSolver is disabled. Pulling on zTet.oMesh while the solver is disabled will no longer work.

• Make initial fiber endpoints work on meshes with multiple connected components. Previously, the fiber would be created and instantly cause an error in the scene.

• Fixed bug that sometimes causes fibers to draw in grey when multiple fibers are selected.

• Fixed bug that sometimes left the effect of a zFiber node even after the node was deleted.

• Minor fixes to the undo/redo behavior of ziva, zPaintAttachmentsByProximity, and zMeshCheck MEL commands.

## Version 1.2¶

### Functionality¶

• Improve performance on scenes with cloth – twice as fast on some simple benchmarks.

• Improve performance in general.

• Modify mesh quality requirements for “ziva -tissue” and “ziva -cloth” commands. They are more permissive about triangle quality than before, but more picky about manifoldness. The goal is to work with more meshes out-of-the-box while still rejecting meshes that are sure to cause problems.

### Command Changes¶

Command

Purpose

Check meshes for potential problems.

## Version 1.1¶

### Functionality¶

• Add “rest-scale” to make cloth shrink like shrinkwrap (or grow).

• Add “pressure” to apply an external pressure force to cloth. Pressure and rest-scale are useful for wrapping fascia around muscles.

• Significant performance improvements to tetrahedralization. Previously, we have advised setting zTet.tetSize to a large value and using surface refinement and refinement propagation to get high resolution where you need it. That workaround is no longer necessary and will be slower than setting tet-size directly to what you want. Surface refinement should only be used if you actually want spatially-varying refinement.

• Lazy license checkout. The plugin only acquires a license once a node or command is run, not when the plugin is loaded.

• Mesh analysis checks for negative-volume (inverted normals), which will usually look fine, but completely breaks material attributes, particularly on subtissues.

• Significant performance improvements to zFindIntersections command (menu item “Ziva Tools” → “Find Intersections”).

### Bug Fixes¶

• The plugin won’t load in “maya -prompt” mode.

• Random crashes due to invalid internal constraints on cloth.

• A sliding attachment with a subtissue target crashes maya.

• Unstable cloth when rest shape was folded over itself.

• Save and Load zCache dialogs no longer filter for file type when set to “All Files”

### Attribute Changes¶

Node

Attribute Change

Purpose

zMaterial

To support fascia simulation and more general cloth sims. In actual fact, restScale was present in 1.0, but it was undocumented and unsupported.

zCloth

To support stable runup with restScale and pressure effects.

## Version 1.0 hotfix 2¶

### Bug Fixes¶

• Fix crashes or incorrect behaviour when tissue tets are larger than 1 meter across.

• Fix incorrect spurious attachment of cloth vertices to other nearby parts of the same cloth.

## Version 1.0¶

### Functionality¶

• Add zLineOfAction to enable semi-automatic muscle fiber excitation.

• SubTissues - for volumetric material authoring.

• Add zPolyCombine - a fast poly combine node. We use this internally because the Maya polyCombine is much too slow.

• Empty Cavities mode on zTet mesh allows users to create internal cavities in tet mesh. For example, when meshing a fat layer over the entire body, this mode will not fill the rest of the body cavity with material.

• Increased accuracy of tissue mass and stiffness for tets partially outside the tissue surface. Depending on resolution, this can reduce object mass and jiggle relative to previous versions.

• Cloth - our cloth material model is no longer experimental. It is significantly more stable than past releases. It’s not a general cloth solution yet, but it is good for simulating fascia and skin.

• Muscle Excitation is now visualized with a fiber color change.

• Automatic fiber endpoint selection when adding a fiber node. Manual painting is still recommended, but it will paint a default automatically.

• Logging improvements. All logging has controllable verbosity. All logging goes to the script editor and a log file.

• Lots of performance improvements, affecting:

• Simulation caching

• Collision detection and response

• Attachment creation

• Material interpolation

• zEmbedder

### Bug Fixes¶

• Fix memory leak affecting cloth, volume conservation, inertial damping, and hard attachments/contacts.

• Fix out-of-bounds memory access during tetrahedralization.

• zBones no longer draw when disabled.

• Fix random crash on Linux.

### Node Changes¶

Node Change

Purpose

Automatic muscle fiber excitation

Fast alternative to Maya’s polyCombine

### Attribute Changes¶

Node

Attribute Change

Purpose

zTissue

To support subtissues.

zTissue

To support fast re-opening of scenes. Internal use only.

zTet

Change fillInterior from bool to enum.

To support a new option ‘Empty Cavities’. See Tetrahedal Meshes

zTet

Same purpose, but the new parameter is easier to explain and understand.

zEmbedder

Remove iSolverParams

No longer needed.

zCloth

Remove collisionVolume

This never worked anyway.

zIsoMesh

To allow a faster and more accurate algorithm on watertight input meshes.

### Command Changes¶

Command

Purpose

To support subtissues

To support subtissues

To enable automatic muscle excitation.

To help make rigs for automatic muscle excitation.