Bifröst ColliderProps attributes

The Bifröst colliderProps attributes control the collision properties of the mesh objects that share this property. See Work with Bifröst colliders.

Container Attributes

Enable

Enables evaluation of the entire container node.

Evaluation Type

Controls how the node is evaluated. Normally, this should not be changed.

Simulation: The node gets evaluated based on the previous frame.
Property: The node is used only to set values used by other nodes.
Mesh Property: The node is used to set values on polygon mesh objects, such as emitters, colliders, and other meshes used in a simulation.
Per Frame: The node is evaluated every frame, but does not depend on the previous frame. This mode can be used for animation or reading cache files.

Properties

Enable: Enables the associated objects to act as colliders.

Conversion

All colliders in a simulation are converted to voxels, which are then used to determine whether a region is inside the corresponding volume or not. The Conversion options control how the objects associated to each colliderProps node gets voxelized.

For colliders, the base width of each voxel is the product of the Master Voxel Size attribute in the Resolution group of the liquid or aero properties node and the Voxel Scale attribute in the Collision group of the liquid or aero container node.

Mode

Controls how the object is voxelized:

Solid creates a solid volume including the mesh interior. The mesh should be both manifold and watertight.
Shell create a thin shell around the mesh surface. In this mode, Thickness should typically be 1.0 or more.
Solid (Robust) is an alternative to Solid that usually gives better results for volumes with fine detail, openings leading to cavities, or non-watertight surfaces. However, it does not handle fluids inside completely enclosed regions.

Coarsen Interior

Saves memory by performing additional coarsening of the voxels inside the volume when Mode is Solid (Robust), especially with self-intersecting meshes.

Offset Surface Distance

The distance in voxel widths used to close (dilate and then erode) the solid voxels when Mode is Solid (Robust). The internal minimum is 1.0 so only values greater than that have an effect. High values can create artifacts.

Thickness Units

Whether Thickness is in Voxels or World Space units. When set to Voxels, the effective thickness depends on the Master Voxel Size of the simulation.

Thickness

The amount to thicken the mesh. For solid shapes that are already quite thick, you can use 0.0 for a precise boundary or even negative values to shrink along the surface normals. For thinner volumes and shells, you should use larger values to prevent holes.

Note that thickness will round off sharp corners. In turn, this can cause other effects. For example, liquid particles may flow along the underside of a collider after flowing along the curved corner.

Voxel Scale

Scaling factor for the Master Voxel Size used to initially voxelize meshes that share this property. See Control the voxel resolution of a Bifröst simulation.

Velocity Scale

Controls the proportion of velocity from the colliders' animated transformation and deformation that is "seen" by colliding fluid in each of the world X, Y, and Z axes.

At the default value of 1.0, any fluid that collides with a mesh reacts normally to the mesh's animation.
At 0.0, the fluid reacts as if the mesh is motionless, regardless of the mesh's actual animation.
Between 0.0 and 1.0, the fluid reacts as if the mesh is moving more slowly. For example, this can be used to dampen the splashes created by a fast-moving collider hitting a volume of water.
Above 1.0, the fluid reacts as if the mesh is moving more quickly. This can be used to exaggerate the splashes from a collider hitting a volume of water.
Below 0.0, the fluid reacts as if the mesh is moving in the opposite direction from its actual animation.

Additional Velocity controls

These attributes work together to apply an optional, extra velocity that is taken into account by colliding fluid, and which is independent of the colliders' actual animation. For example, you can set these on a static collider to make colliding fluid behave as if the mesh was moving.

Enable Additional Velocity: Adds extra velocity to any existing velocity.
Additional Velocity Mult: A multiplier that scales Additional Velocity uniformly in all axes.
Additional Velocity: The base velocity to add in world coordinates.

Boundary Controls

Limits the effect of the associated mesh objects to their intersection with an implicit shape. See Limit the volume of a mesh's effect using boundary controls.

Enable Boundary: Activates the boundary controls.
Boundary Shape: Selects the shape of the boundary volume.
Invert: Restricts the effect of the mesh to the exterior instead of the interior of the boundary volume.

Adaptivity

Refine Nearby Fluids: Prevents the fluid resolution from being coarsened in regions that are close to the collider when spatial adaptivity is enabled on the liquid properties node. Turn this option off for colliders where less detail is needed, for example, on the bottom and sides of pools, and turn it on for colliders where you want full detail. This does not affect the free surface (air boundary), which always uses full resolution. See Control spatial adaptivity.