I've had the mind to create a filter that would make tiled blend passes simple since I published Digital Evolution 14 years ago. I recently came back around to it; I've a lot more experience with graphics and shaders now and it seemed sensible to make something using shader code.
I actually originally was going to write it in Vulkan, but I wanted to skip the boilerplate and the fact that you need to compile shader code to SPIR-V first - while SPIR-V is sensible, it complicates the code here. OpenGL lets me defer that functionality to the driver.
If you just want to try it out, build glslfilter-glfw and see /demo/crt-singlestage and/or /demo/divergence
