Is there a way of copying one texture into another one using a shader? The same way unitys Graphics.Blit allows you to pass in a material that takes in the source texture as a uniform parameter and its result is written to the target texture.
Alternatively is there a lowlevel graphics API I'm missing that allows me to set the render target and render meshes immediately so I can implement blit functionality myself?
I looked around in the examples and stumbled upon the postprocessing docs which told me to implement a multipass postprocessing effect via the scene hierarchy which seems like design hostile to the flexibility I'm looking for?
My direct usecase is that I'm looking to make a pixel art program where I have a rendertexture for each layer and I need custom shaders both for using tools/brushes on it as well as combining it with previously rendered layers and its child layers. In some cases those tools also need textures to remember a state while drawing and all of that drawing is highly order specific, something I don't feel secure of when letting a viewport in the hieararchy render "whenever".