Vellum Source emits new patches of Vellum geometry into a Vellum solver. Vellum patches consist of both the geometry of the patch and the geometry describing the constraints on the patch, so some bookkeeping is required to update everything properly.
A Vellum simulation object has Geometry data which describes the surface of the patch. It has ConstraintGeometry data which describes the constraints holding the patch together, and should be a one-to-one matching of points with the Geometry data. Finally, a PatchGeometry data stores the names of all the patches to tell if they have been emitted or not.
Controls if the Vellum source will emit or not.
How patches will be emitted from the source geometry.
The geometry will only be added once to the Vellum object. Note the patch name is used to detect if it has been added.
Geometry is added every frame that this DOP is active. Does not add during substeps, only on new frames.
Geometry is added every substep that this DOP is active.
Instance on Points
Like Each Frame emission, geometry is added every frame the
DOP is active. However, a point geometry is also provided
to instance the patches on. The point geometry’s instance
N) are used to instance the
patch; matching the Copy to Points behavior.
When sourcing grain or fluid particles, this node checks the density of the new particles against the existing particles to avoid having too many particles in one place and causing large outward velocities. This parameter allows scaling the permitted density, with lower values making the emission sparser and higher values making it more full.
Path to a SOP to fetch the surface geometry of the Vellum patch.
SOP Path to use as the target for the Vellum patch. When points are set to follow the target animation, this is the path used. Note that the path will be re-evaluated at every substep.
Constraint SOP Path
Path to a SOP to fetch the constraint geometry of the Vellum patch. Should be in a one-to-one point correspondence of the surface geometry. Note that because you cannot point to an extra output, you may need a Null SOP to act as a target to a Vellum Constraint SOP.
In instance mode, this SOP’s geometry will be used to instance Vellum patches. A patch will be created for every point in this geometry and positioned and oriented according to the point’s attributes.
Copy Instance Attr.
When instancing, these point attributes will be copied to the
instanced geometry. Adding a
instanceid allows you to track
which point each instance came from to further control the
A Vellum Constraints Property DOP will iterate over the
ConstraintGeometry, not the
Geometry, so not directly be able to access
these. However, the Geometry is bound by default, allowing
point(1,"aname",@ptnum); to be used.
Vellum Patch Name
All the points of the Vellum patch will gain a
with this value. This is used to recognize if a patch already exists
for the Emit Once mode, and can be used to separate out the different
patches after the simulation is complete.
POP forces can be applied to a Vellum patch by wiring them after the Vellum Source node. The streamname allows the POP forces to properly isolate their behavior to a single patch.
When fetching the geometry from other SOPs, the other SOPs world transform usually must be applied to transform to the right space. This is the Into This Object mode.
However, if the DOP solver is inside a sop, and the source are other sops at the same level, using the world transform will double apply it and the None mode should be used.
Name of the data on the simulation object to use for the surface geometry.
Name of the data on the simulation object to store the constraint geometry.
Patch Index Geometry
Name of the data on the simulation object to store the list of patches.