nParticles with instancer and random scale


I have a scene where I have a cup that i’m trying to fill with 4 different kinds of berries.
I have the cup filling and the berries are running through the instancer just fine, problem i have iw that i cant randomize the scale of the berries.
if i randomize the scale then the collision radii dont sync up, and if I randomize the the radius, then the geometry collides with gaps between them.

I have tried a few different ways, but somewhere i seem to be missing something.
anyone have more ideas on what I could attempt



what Maya version are you using? This was a bug once upon a time :wink: that was fixed and only the collision thickness display was wrong. But since 2017 this should also be fixed.



working in Maya 2018


In what way are you randomizing the radii? Are you using the internal radius ramp?


I dont think so, it doesnt seem to be hooked up anywhere.

i was just trying to use a “=rand (.4, 1);”


something isnt wired up properly, if i use the radius ramp it does nothing


Is the internalRadiusRamp connected to the radiusPP attribute? It should connect automatically if radiusPP is not used within an expression and you change settings on the radius ramp.


it did create the link when i set the ramp to normalised age, but it still isnt changing the size


ok, so i can get the particle shape to randomize, but if i turn on spheres (under shading so i can see the collision particles) my mesh objects from the instancer always seem to be smaller than the collision sphere


You should be able to simply scale your objects until they match the particle radius.


well, the scale is random, so if i change the scale of the objects, I will still have the same issue where some will be bigger and others smaller than the collision radius


setting it to scale using the age makes the particles/objects change through the whole animation, i need it to randomize scale on creation only


The reason your instances don’t sync up with particle radius is because those attribute aren’t connected by default. Instance size is controlled by a scale attribute on the Instancer (Geometry Replacement) section. You can connect radiusPP to the scale of the instanced geo. Should solve your issue.