Object parts to particles

General TouchDesigner Discussion
1

I have model that consists of 100 objects. I want to control these parts with particles(each part must be attached to 1 particle)

Is there any way to realize this?

2

Yes, first create your 100 particle particle system and then get the tx, ty, tx or each particle into CHOPs using a SOP to CHOP. Following this, use the chopi() expression to fill the tx,ty,tz parameters of the geometry with the CHOP values in the SOP to CHOP. It would be easier to setup if you named your 100 objects serially like obj0 … obj99, then the expression in the tx, ty, tz parameters would be:

chopi("sopto1/tx", $OD), chopi("sopto1/ty", $OD), chopi("sopto1/tz", $OD)

where $OD is the digits at the end of each object’s name.

3

Interesting method but i have a few questions about it:

  1. Initially i need to place each particle in the middle(or pivot point) of each part of the model. As i undestood you offer to make inverse operation and place objects in the particle positions?

Here is the example of the model to better undestand what i’m talking about(it’s torus which consists of 79 parts)
torus_79pieces.rar (159 KB)

  1. How the model must be organized to use chopi expression in automatic way for all of the parts(parenting parts, separate file for each part or some another issues)?
4

If you need the particles to start at specific locations, you can first create points at the desired locations and then merge all your points into the input of the Particle SOP and set the Behavior parameter to Modify Source Geometry. Now no particles will be born or die off, there will be a static number of particles defined by the input geometry points.

  1. Using the $OD trick I mentioned below requires that each model you are adding sits inside a Geo COMP named obj?? that is part of a serially-numbered series of Geo COMPs. It is like having an array of Geo COMPs in which the expression can then use the digits in the name of the Geo COMP to access the correct sample of data in the SOP to CHOP.
5

Please, tell me how are you controlling all array of the GEO comps with one expression at the same time :question:

6

Here’s a small example with 4 Geo COMPs controlled by the position of 4 particles. If the Geo COMPs were all holding the same geometry, you should use instancing in the Geo COMPs, but I assumed your models would be different.

Note that the numbering of the Geo COMP names is used to pull the correct sample from the CHOP channels.

objParts2Particles.tox (3.55 KB)