Supersampling/Viewport Scaling in 2D

@Calinou Yeah, it should work in 3D fine as it's just sampling a color image, so it doesn't really matter if it's 2D or 3D. I'm going to test it today in 3D, because I need to determine how it stacks up against MSAA and FXAA. I'm fairly certain it should be better than FXAA, but MSAA is already optimized in hardware so I'm not sure how it would compare (especially for performance). And the code is all working, but I want to test it a little more with some other projects to make sure it works in a more general case. It may take me a few more days, but I would definitely like to add this on the demo repository.

Here is the latest version with a 5K image sampled down to 1440p getting over 5,000 fps on an RX 6800 XT.

This is the latest version. I fixed a major bug, so it doesn't look quite as smooth, but is more accurate with realistic content. I think I've optimized as much as I can, but it is still pretty slow on low-end devices. I would advise against pushing it up to 200% as many older PCs and phones may not be able to handle it. I'm working on an FXAA shader and Lanczos upscaling, which also look quite good and are much faster (don't require such a high render scale). They are not finished yet, may take me a few more days. Here is an image of the latest version SSAA at 4K highest settings.

I'm finishing up on my shader. 3D works perfect now, just need to verify that 2D is still working after all the changes I've made. I should be ready to publish in the next few days. This new version should be more optimized and provide better quality, so please hang tight for a moment.