How to use TOP input to move XY of instances

I would like to use the luminance strength from a TOP to transform the XY positions in a set of instances with the Geo Comp. The Geo Comp operator snippet has a great demo on how to create a grid and displace the Z axis with video - however controlling the XY coordinates seems tricky.

I would like instances to move towards the brighter part of an image and have nothing positioned in the darker areas.

I tried fiddling with different ways of mixing other TOPs into my existing UV ramp (whatever those colored gradients should be called?) but I know there is some knowledge I’m missing here.

I’m running into a similar problem when trying to plug a TOP directly into the GPU particles operator and only getting a diagonal line. Have been scanning the forums and tutorials all day but haven’t been able to find an answer to how this works. Any help with this issue or on understanding how to manipulate these ramps properly would be much appreciated!

XYtopInstanceQ.toe (6.4 KB)

Hello,
Looking quickly at your project,
– put all the Tops in 32bits float mode, as to allow negative and precise positions.
– put the offset of your noise to zero as to center the point cloud to 0,0,0
– use math Top to center your ramp (-1 to 1)
– put your operators in a logical order as to have a clear understanding of your intentions.
But more deeply, its not the same operation to move a point (change the z position) according to the color value of the same point (as in the snippet) and move the same point in two dimensions according to a color value. Its possible to move it with the red value for x move and the green value for z move, as in displace Top.
I made a quick example with a noise displacing particules (changing amplitude from 0 to 0.5) and with a movie, using math to scale the red an green value to -0.2/0.2.
With GLSL Top, feedback and compute shader you would have a very versatile system…

Perhaps that example can help you to find your way.
Jacques

TD Move Instance.toe (7.0 KB)

Hi Jacques. Thanks so much for putting this explainer together for me! I think this is pretty much want I wanted to be able to do. So you’re not translating on X&Y but instead X&Z?

Going to have to try to wrap my head around whats going on here (still having trouble understanding how the colors are translating to a coordinate system). Seems like a good staring point - hope I can make sense of it somehow!

Tristan

You can easely move also the Z adding the monochrome image tto the blue color of position, like that:

TD Move Instance.3.toe (7.1 KB)