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The Pyro Source Pack SOP creates a packed source set from its input volumes. A packed source set consists of a packed primitive containing the source volumes, along with the rules on how to apply them to a pyro simulation. Several packed source sets can be merged together to form a library. You can then randomly assign different elements from a library to scattered points.
Geometry with either source volumes or rigid body pieces to turn into a packed set.
Packed Source Set
A packed source set created from the input.
For packing pyro sources, choose Volumes to Source. Choose the Rigid Body Pieces if you want to pack fractured objects or multiple objects as collision geometry for pyro volumes. Incoming rigid body pieces are rasterized.
The name of the packed pyro source set. Use a unique and descriptive name, because it is also required in the Pyro Spawn Sources node’s Source Name to specify the source set you want to instantiate.
Subset of the input sources to pack.
Reference frame for the packed source set. All sources in the packed set in are timeshifted to start on this frame for consistency. The value of this parameter should match the Reference Frame on Pyro Source Instance nodes that are used to generate instance points for the packed set.
Define, which frames of the input source are packed.
Convert to VDB
When turned on, the input source is converted into a sparse VDB volume. Otherwise, a Houdini volume is used.
The packed rigid body pieces are rasterized into VDBs with this edge length. Smaller values create a better representation of the source object, but at the expense of using more memory.
The name of the collision volume’s signed distance field (SDF).
Expand the collision object’s volume by this number of voxels to make it thicker and improve object-pyro collision.
When turned on, the objects are converted into filled and solid volumes. When off, only the object’s surface is rasterized, while the interior remains hollow.
Number of Sources
Enter the number of source volumes you want save with the packed sources. Number and names of the volumes should match the Attributes parameter on the Volume Rasterize Attributes. You can add new source volumes with the + button, or remove them with -. Clear removes all volumes.
Turns the volume on and off. The volume is only active if this value is greater than
0. Use this parameter to quickly test the simulation with or without this volume.
The merging operation.
Values in the Target Field will be overwritten by those in the Source Volume.
Result is the sum of values in Target Field and Source Volume.
Result is the difference between values in Target Field and Source Volume; the difference can optionally be clamped against zero by enabling Avoid Negatives.
Result is the product of values in Target Field and Source Volume.
Values in the Target Field will be divided by the corresponding values in the Source Volume.
Result is the larger of the values in Target Field and Source Volume. For vector fields, comparison can be performed length-wise by enabling Use Vector Length.
Result is the smaller of the values in Target Field and Source Volume. For vector fields, comparison can be performed length-wise by enabling Use Vector Length.
Result is the average of values in Target Field and Source Volume.
Values in the Target Field are pushed towards the corresponding entries in Source Volume, in accordance to settings of Acceleration Strength, Deceleration Strength, and Direction Strength.
Result stored in the Target Field is
(s * v + d * w) / (v + w),
w represent values of the source, source weight,
target field, and target weight, respectively. Additionally, the values
of source weight are added to the target weight field.
The Target Field is left untouched.
Rank of the target field.
It is extremely important to identify data type for fields that the DOP object does not already contain. In these cases, a new field is created with rank governed by value of Field Rank (assuming Create Missing Fields is enabled).
Name of the SOP volume or VDB to merge. For vector fields, this can be a single vector VDB or a space separated list of three scalar volumes or VBDs.
The DOP field that is to be modified.
A multiplier applied to the source values before merging.
Controls how strongly the Target Field's values are pushed towards the Source Volume. Applies for the voxels in which the Source Volume has larger values than the Target Field.
Controls how strongly the Target Field's values are pushed towards the Source Volume. Applies for the voxels in which the Source Volume has smaller values than the Target Field.