Is it possible to change the frame offset on a video texture when instancing with GeoNodes?

Question

I'm fairly new to both blender and geonodes (coming from TouchDesigner / AE) and this seems like it should be a pretty easy thing to do but I am having a lot of trouble figuring it out.

I am using geo-nodes to instance a large number of planes, on those planes is a material playing back a video with an alpha channel. I am trying to get the offset of the video to be different either for each instance or simply just at different Z-depth, however the offset control on the image texture node doesn't have a link to it. I tried some other methods like using drivers but the more I looked at it the more it just seemed like even if the offset changed it was going to apply globally to all the planes, not as they are instanced.

Here is a pic of what I am talking about.

I have seen a couple of posts doing something similar with image sequences where each instance shows a single image in progression, but I am trying to get each to playback an entire video, just offset from each other. I have also seen some answers to get instance data to the shader graph by realizing them, but I am unable to figure out how to put those things together so that the material is different for each instance or set of instances.

The only noob solution I've found is to just make different materials for each set of instances but I'd end up with around 100 materials. Any insight would be appreciated.

Answer 1

No.

Unfortunately, the way it is now, each Image Texture node represents a single frame of a sequence each time the node tree is evaluated. In geometry nodes this means each object has its copy¹ evaluated once per frame. In shaders the node tree is evaluated once per frame, so no driver gymnastics will help.

The only workaround, other than creating multiple materials, is to merge all frames into one big image texture, and cut out the frame of interest out of this texture. Or a combination of both methods, multiple materials, each containing an atlas of multiple frames.

¹ - even if multiple objects share the same geonode tree, because it is wrapped in unique modifiers for each object, effectively the parameter passed to the Image Texture node can be different for each object - not that it matters that much as in geonodes image texture don't support sequences.