The Bifröst
acceleratorProps attributes control the acceleration properties of the mesh objects that share this property. They may be found in scenes created with older versions, but for more control over velocity you can use
motion fields instead.
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, accelerators, 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
- Toggles the effect of acceleration due to this object.
Conversion
All accelerators 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
acceleratorProps node gets voxelized.
For accelerators, 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
Acceleration 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.
- 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.
Acceleration
Geometry Influence
-
Influence
- A multiplier for the total acceleration effect (Inherit Velocity,
Direction Magnitude x
Direction, and
BoundaryLayer combined). Values greater than 1.0 exaggerate the effect, and values between 0.0 and 1.0 reduce it.
-
Inherit Velocity
- Applies acceleration based on the animated translation of the accelerator object. The effect is cumulative, so the particles' velocity continues to increase while they are within the accelerator's influence.
-
Falloff Bandwidth
- A thickness around the accelerator in world-space units. Acceleration is applied to particles within the accelerator at full strength. Within the bandwidth, acceleration is applied with a falloff that reaches 0 at the outer limit.
-
Direction Magnitude
- The strength of acceleration along the
Direction vector.
-
Direction
- The world-space vector along which to apply acceleration.
Boundary Layer
Pulls liquid along with the accelerator by gradually matching the liquid's existing velocity to the velocity of the accelerator. If the accelerator is not moving, the effect is similar to a drag force.
- Boundary Layer Strength
- Controls how quickly the velocity of the liquid within the accelerator and boundary layer converges to the velocity of the accelerator.
- Boundary Layer Bandwidth
- The thickness around the accelerator (in world space units) of the boundary layer effect. Liquid within the accelerator receives the full effect, and liquid within the boundary layer is affected with a falloff.