Applying random obj file on each point using Copy / GLSL Copy POP.

POPs
1

Hi team,

I’ve tried to solve this issue for a few days on my own. I’m a beginner to TouchDesigner, so excuse me if the question is basic!

My goal is to

  • Apply random obj file on each point. The obj files are in “base1” COMP. Different “idP” attribute has been assigned to each obj file. “glsl1” POP assigns random idP value on each point. Ideally, I want to use a lot of obj files but I reduced the number for faster performance atm.
  • After applying the obj file, scale and rotate each point reacting to CHOP values. “copy1” POP achieved what I wanted to accomplish except all the copy is the same geometry.

The problems are:

  • Rot and PointScale attributes from second input to GLSL Copy POP aren’t picked up. (= Each copy isn’t scaling nor rotating.)
  • Periodically all the random shapes becomes the same shape. Probably it has something to do with the “glsl1” POP, but couldn’t pinpoint what’s causing it.

I’ve looked at this post as this person was achieve the goal that’s similar to mine, so I applied some tricks from the post into this.

Here is my project file.

20251125_GridKitbash_v103_GlslCopyPop.toe (16.7 KB)

According to the user guide, “all the copies are limited to have the same topology,” so maybe what I’m trying to achieve here isn’t possible yet. It would be wonderful if I could borrow your expertise and insight here.

2

Hi @superhiro,

you would have to calculate the rotation and scale in the point compute shader of the GLSL Copy POP yourself. For this there are a variety of helper functions (for example TDRotateToVector) available which you can find here: Write GLSL POPs - Derivative

Also have a look at the OP Snippet for the GLSL Copy POP and especially at the example “time-offset boxers”. There rotation and scale is applied individually to each copy.

cheers
Markus