Quick question to the community/SESI people…

Is there a good reason why the source POP expects a primitive attribute exclusively? :cry:

Why i'm asking?

Sometimes, when dealing with NURB/Mesh sources, it is helpful to vary the distribution if particles across the surface using some arbitrary attribute - as one can very easily do with polygons, by defining a primitive attribute (of which there would be many).

However, when dealing with NURBS/Meshes… there is exactly 1 primitive attribute/patch. :?

The question begs to be asked - why not allow point attributes in the source POP?

Any thoughts on the matter will be appreciated - and if i'm missing something obvious, please let me know…

Cheers,

Gene

Using the Surfaces (attribute) Emission Type you only have access to primitive attributes. Very handy for polygons but not very handy for NURBs.

You can use the birth probability values and use any of the default Houdini variables. I tend to use $CR, $CG and/or $CB in the min and max fields. I sometimes set min to 0 and max to $CR*10 to affect the particle distribution. The multiplier affects the distribution.

Another approach in H7 is to use the scatter SOP as it has support for any attribute you specify. Just scatter a whole bunch of points then use this as your source for particles.