Accessing the indices of each instance (without realizing instances?)

[majoran (Majo)]

Hi, in my collection I have various mesh lines with wave shapes. Each Instance mesh line has 256 points. I want each instanced line to be multiplied along its 256 points with a window function creating a fade-in and fade-out at the beginning/end. How do I access the indices of each instance?

(I tried realizing the instances and then doing an Index Input + Modulo 256, but at that point I cannot do multiplication between 0 and 1 when having instances along the y axis (here 2 points in y direction on my grid) - then all instances start at 0 world space.)
Thanks for help.

[AlphaChannel (Start Loudly)]

Maybe this helps you…

[majoran (Majo)]

Thank you, no, here the “index” input provides the indices of the grid, but I need the indices of each instanced object.

[AlphaChannel (Start Loudly)]

If you are using one of the later releases you can also move them with this node…

[AlphaChannel (Start Loudly)]

try here…

[majoran (Majo)]

“delete geometry” surprisingly works. But I need something like a ramp along the indices. Still cannot find a solution. See here:

[LordoftheFleas]

If the offset created by the Points input to the Instance node is the problem, you could just subtract the position of the point before scaling:

windowing_function.blend (107.5 KB)

[majoran (Majo)]

THANK YOU. Subtracting / Adding the initial position is key!