Scales the effective time of the solve. This can create bullet-time like effects where the physics of the Otis solver run at a different rate than the Houdini playbar. A value of 2 will cause objects to fall twice as fast, and 0.1 will slow them to one-tenth the speed.

Each frame will be broken into this number of substeps. Additional substeps are required for fast moving collisions or sudden forces. The Otis solver is OpenCL-based and generally only imports target geometry at frame intervals, so increasing Substeps should be less expensive than in some other solvers.

Within each substep, this number of passes will be taken by the material solve. Stiffer materials can require more iterations to converge.

The uniform gravity force to apply.

A damping applied directly to the velocity in the simulation. The velocity is scaled directly by this amount, causing sudden movements to be quickly damped.

A threshold at which to apply full friction. When the ratio of the tangential velocity and the normal impulse is less than this, the tangential velocity will be fully eliminated through friction.

If the static threshold fails, this controls what percentage the tangential velocity will be reduced in the dynamic friction case.

Clear the simulation cache so that the simulation starts over.

Controls if the simulation is cached to memory.

Maximum size of the memory cache.

When any parameter inside a DOP simulation or any referenced external node is changed, the cache of the simulation is marked as invalid. When 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 remains the same other than to be marked invalid. When off, the cache is marked as invalid in 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.

Style of the simulation.

The frame at which the Dynamic simulation should begin.

Because a Quasistatic solve can operate over multiple poses with no visibility into the intermediate states, this option can write out geometry in the intermediate state.

The base name to use for any intermediate files output. A five-digit substep or pose number will be appended as well as .bgeo.sc.

The scale for convergence acceleration within the solver. Increasing this value can make the solver converge faster for more accurate stiffness but setting it too high can lead to instability.

Improve solver convergence by adaptively increasing the stiffness on stiff constraint types that compete with softer constraints. Currently this applies only to tetrahedral volume constraints.

Perform the material solve in double precision. This option is more expensive even on advanced GPUs, but can avoid instability when solving extremely small, stiff tetrahedra.

Points on the simulation mesh can be marked as Pin to Target to follow the targeted animation. By default, this target is the first input. But in some cases the animation to target may be present in another SOP node, so that can be specified here.

The path of a node to refer to when simulation points are set to the target animation. Should have a one-to-one point correspondence with the simulation points.

When some parameters on the Update Constraints from Target tab are on, the solver will update constraint attributes directly from the Target Constraints. By default, this target is the second input. But in some cases the animation you wish to target may be present in another SOP node, so that can be specified here.

The path of a node to refer to when simulation constraints are set to the target animation. Should have a one-to-one primitive correspondence with the simulation constraint primitives.

How frequently to update the target geometry.

When on, the Quasistatic solve will process each packed primitive as a separate input pose, allowing a smooth transition from an initial state to a more extreme pose in a smooth manner that can be defined by the series of poses. If Target Constraint Method is set to a SOP Path, you can also provide the same number of packed constraint geometries to modify the constraints over the series of poses. An example is to flex muscles as they bend.

Integrate velocity within the Quasistatic Solve. This velocity can be used as a predictor between poses, allowing the solved geometry to track the input poses better.

When performing a Predictive Quasistatic solve, smoothly scale up the Velocity Damping to 1 over the final specified number of frames. This can be useful to remove any inertial movement in a Quasistatic solve. Usually the final packed primitive pose should be achieved and held stationary for this number of frames as well.