Tormentor667 wrote:So what is restricting this?
Less and less, luckily. Initially it was a messy abstraction caused by ZDoom and GZDoom not being the same repository. Luckily Graf has cleaned this up a lot the last few years. The vulkan work will improve this even further as it will ensure the abstraction doesn't directly rely on OpenGL calls like it did far more in the bad old days.
Main thing restricting it right now, aside for someone committing to the work, is that the engine needs to know when a rendering includes a water plane so it can make a copy of the scene buffer. This needs to be done at exactly the same place as the SSAO pass already copies the depth buffer. And like with SSAO there are portal trade offs where such kind of water should be avoided as much as possible near those. A good implementation would therefore also require possible fall back to a simple classic water effect for people on less powerful GPU's.
Graf Zahl wrote:Maybe the simple fact that for rendering realistic water you need a bit of info about the environment?
Naturally, most of the super fancy effects won't be possible to do as they won't be compatible at all. 2000-2005 age water effects should generally be possible and IMHO often look better artistically than the newer stuff anyway.