Multiplier applied to the timestep used by the solver.

The number of DOP substeps for each simulated frame. This should generally be kept to 1 for performance reasons, but could be increased to achieve smooth continuous emission.

The fraction of voxel width that a particle is allowed to travel within a single timestep.

A multiplier on the maximum timestep allowed based on the simulated material properties. To maintain the integrity of stiff materials, impulses need to travel very fast through the material. This imposes a constraint on the maximum allowed timestep similar to the CFL Condition. Increasing this value or reducing the stiffness of the simulated materials will relax this constraint and could speed up the simulation.

Limits on the minimum and maximum number of substeps.

The solver dynamically picks the lowest substep count based on the type and speed of the material. Although the max value is set at 10,000 by default, it doesn’t mean 10,000 are necessarily being used. You can see the actual substep count on the outputted geometry as a detail attribute. The high default value is to account for stiffer materials, like concrete or metal, that will require more substeps and are expected to be slow.

The gravity acceleration.

The amount of air resistance bringing the material to match the wind’s velocity.

The uniform wind’s velocity.

Creates a ground plane.

Defines how the ground plane should affect the material on contact.

Location of the ground plane in space.

Normal vector or orientation of the ground plane.

Rotation applied to the normal vector of the ground plane.

Scaling factor applied to the infinite ground plane visualization in the viewport.

Amount of friction applied from the ground plane to the material, when in contact.

Allows projection of the material velocity even when moving away from the ground plane. This prevents the material from detaching from the ground plane, making it sticky if friction is high enough. If the dot product between the normal vector of the ground plane and the velocity of the material is smaller than this value, the velocity of the material gets projected onto the ground plane.

Amount of memory to use to cache the simulation.

When any parameter inside a DOP simulation is changed, or when any referenced external node is changed, the cache of the simulation is marked as invalid. If this parameter is turned on, the next time the playbar is moved to reach a simulation time of 0, the cache will be cleared and the first simulation timestep will be recalculated. If the cache is invalidated while at a simulation time of 0, the initial state is recalculated immediately. If the current time is beyond time 0, then the most recent timestep will be recooked, and the cache beyond the current time will be cleared. But all prior timesteps will be left untouched other than to be marked invalid. If this parameter is off, the cache is marked as invalid in exactly the same way, but the cache is never cleared automatically. To recook a simulation in this mode, the Recook Simulation button on this parameter dialog or above the viewport must be used.

Ensures that the particle-to-grid transfer is performed in a deterministic manner, which means that running a simulation multiple times will always yield the exact same result. Disabling this feature will prevent the simulation from being consistently reproducible. In general, the deterministic algorithm will yield better performance when particles are tightly packed together. On the other hand, isolated particles that are sparsely distributed in space like rain droplets or explosive debris could benefit from the non-deterministic version of the transfer algorithm if reproducibility is not required.

Rebuild the VDB sparse background grids on the OpenCL device (GPU) instead of the host (CPU). This feature is turned off by default because of its high memory consumption which imposes a rather restrictive upper bound on the maximum resolution that can be simulated on a standard GPU.

Assumes that the material properties are constant throughout the simulation. This is an optimization that prevents the solver from recomputing the Material Condition on every frame. This should be turned off if different materials are sourced on different frames or if the dive target inside the solver is dynamically modifying the material properties as the simulation runs. Turning this off will slow down the simulation but will ensure stability by keeping the Material Condition consistent.

Allows a second collision step to be performed directly on the material points. This adds some computation but yields more accurate collisions. In general, this can be turned off unless very precise collisions are required such as with thin colliders.

Specifies how particles sinking into colliders should be treated.

Limits the magnitude of the Affine Velocity matrix C's determinant. This prevents C from becoming unreasonably large which often leads to inf and nan velocities. Instability should always be resolved with more substeps or by modifying the material properties, but this parameter can prevent some issues without affecting the amount of energy in the simulation.

Imposes constraints on the dilation of the sparse background grid in terms of voxel. The sparse background grid is only rebuilt every DOP substep (once per frame by default). To make sure material points do not land in inactive regions of the grid, it is being dilated to account for the motion that takes place between two consecutive DOP substeps.

When Finish Kernels is disabled, no attempt is to wait for the OpenCL kernels to complete before continuing the next solver. This lets them run in the background until their results are actually needed. To simplify debugging, it is useful to ensure kernels are finished to make sure errors are detected in the right spot.

When loading kernels from disk the kernel is cached to avoid regenerating it every solve. Turning this on forces the re-loading and recompiling of the kernel. This is useful if #include files refer to code that has changed, or the kernel file is changed in an external text editor.

It should always be disabled when prototyping is complete.

Specify any desired compile flags for the kernel. The most common is to use -D to provide #define directives for the pre-processor.

Point attribute to remap to a color for visualization in the viewport.

Point attribute minimum to map to the 0 of the color ramp.

Point attribute maximum to map to the 1 of the color ramp.

Remap the fitted point attribute values to colors.

Render particles as spheres in the viewport. Override the particle rendering method defined by the MPM Sources.

Render particles as spheres in the viewport.

Override the point scale defined by the MPM Sources.

Multiplies the pscale attribute. This is strictly used for visualization and meshing post-simulation. The volume of each particle is always computed using the global particle separation cubed.

Display a blue wireframe sphere around the pinned particles.

Exports the 3×3 Deformation Gradient matrix F as a point attribute.

Exports the 3×3 Affine Velocity matrix C as a point attribute.

Exports the particle velocity v as a point attribute.

Exports the determinant of the Deformation Gradient's plastic component Jp as a point attribute.

Exports the determinant of the Deformation Gradient's elastic component Je as a point attribute.

Exports the particle radius pscale as a float point attribute.

Exports unique particle identifier id as a point attribute.

Exports the pinned particles' flag as the pintoanimation integer point attribute.

Exports the particle age as the age float point attribute.

Exports the particles' source name as the sourcename string point attribute. This attribute is defined by the MPM Sources for post-sim manipulations.

Exports additional point attributes by name.

Exports the actual number of computed substeps substepcount as an integer detail attribute.

Exports the voxel width of the background grid dx as a float detail attribute.

Exports the gridscale float detail attribute that defines the voxel size of the background grid in terms of the particle separation.

Exports the particle separation particlesep as a float detail attribute.

Exports additional detail attributes by name.