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This SOP unpacks agent primitives for Vellum simulations and provides several higher-level features on top of the Agent Unpack SOP, such as separating the simulation geometry from collision geometry and performing a pre-roll.
If the agent shape to be simulated contains a Vellum setup from the Vellum Pack SOP, attributes on the simulation and constraint geometry will be updated to ensure correct behavior for agents that have been copied or transformed. This includes scaling the constraints' rest lengths for agents that have been scaled, and adjusting the point numbers for welds and attachment constraints when multiple agents are being unpacked.
Specifies how to select the agents that will be unpacked and simulated.
Point or primitive group specifying the subset of agents to unpack.
Any agents whose current layer matches this pattern will be unpacked.
Shapes to Simulate
Any agent shapes matching this pattern will be unpacked as simulation geometry for the first output.
Otherwise, the shape will be unpacked as collision geometry for the third output.
If the simulated shapes contain packed primitives with the
vellum_type primitive attribute (i.e. from the Vellum Pack SOP), the simulation geometry and constraint geometry will be split into the first and second geometry outputs.
Specifies a list of attributes to delete from the unpacked geometry. This can be useful for removing attributes that are not needed for downstream operations, such as capture attributes.
Specifies a list of attributes to transfer to the unpacked geometry. Computed point velocities will be transferred if both "v" and "w" point attributes exist and are specified.
Specifies a list of groups to transfer to the unpacked geometry.
Vellum Start Frame
Specifies the start frame that will be used for the Vellum simulation. If this is earlier than the Crowd Start Frame, a pre-roll will occur.
Crowd Start Frame
Specifies the initial frame of the input agents.
Use Rest Clip
If enabled, the pre-roll will blend each agent from the pose specified by the Rest Clip and Clip Time to the agent’s pose at the Crowd Start Frame. Otherwise, the pre-roll will blend from the agent’s undeformed (rest) geometry to the deformed geometry at the Crowd Start Frame.
Specifies the clip to use when Use Rest Clip is enabled.
Specifies the clip time to use when Use Rest Clip is enabled.
This example demonstrates a simple workflow for simulating cloth on a crowd of characters using the Vellum solver.
The following examples include this node.