@HungryDoodles I’ll post more later but here’s an update. I was able to edit the 2048x2048 directly in C++ code at run-time, but it crashes unless I disable mip maps when I write to the texels. It doesn’t make sense - I don’t think there’s any good reason why mipmaps have to be disabled to write to a texel, so maybe I’m doing something wrong, but I actually think UE4 is just broken here. I’m also using an uncompressed texture format with colors when I’d prefer a binary texture or whatever uses the least bits, because that’s what seems to work…
In any event, for now I’m thinking I want the 2048x2048 to use mipmaps for better performance… So I’m using a separate 32x32 texture without mipmaps for dynamic texture edits in C++ at run-time.
I haven’t figured out the mapping yet. It’s not just a matter of 2048x2048 divided by 64 equals 32x32, because there’s an offset in the top-left corner and a max in the bottom-right corner, but I’m working on that… The material takes UV coordinates as input in the range of 0.0f to 1.0f rather than 0 to 2047.
Another issue is that my 32x32 sampler has to be linear color, and I’m not sure how to do nearest point sampling (directx/opengl jargon).
Thank you for the ideas, I’ll post more later…