Houdini 16.5 Particles

Inspecting attributes

Use the details pane to show the values of the attributes on particles in a particle system.

  1. Choose Windows ▸ Floating Pane to create a new window, then press Alt + 8.

    Alternatively, you can simply change an existing pane into a details pane by pressing Alt + 8.

  2. Navigate to the POP network.

  3. Make sure the spreadsheet is set to show attributes for Points (use the drop-down menu).

    The spreadsheet should show one row for each particle in the system, with columns for each attribute.

Reading the pstate attribute

The pstate attribute is actually a "bit field", storing several different state flags in a single value. Houdini calculates the value of pstate by adding up the following values for each flag that is on:

Flag Value
Primary 1
Dying 2
Stopped 4
Collided 8
Stuck 16
Sliding 32768

In addition, the pstate indicates the state of rule suppression.

Flag Value
Suppress all 32512
Suppress position 256
Suppress velocity 512
Suppress up 1024
Suppress age 2048
Suppress reap 4096
Suppress rotate 8192
Suppress angular velocity 16384

One way to check if a certain "bit" is on in the pstate value is to open a Python shell and use the & operator.

>>> # For example, if the pstate is 27
>>> # Dying?
>>> bool(27 & 2)
>>> # Stopped?
>>> bool(27 & 4)
>>> # Stuck?
>>> bool(27 & 16)

In expressions you would use individual local variables such as $STOPPED instead of reading pstate.


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