Terrain water’s reflections have some obvious artifacts.
Here’s a screenshot showing a bunch of them:
Namely, under the butterfly, under the tree’s bough, and along the sides of the reeds.
This is extremely noticeable, especially while moving. The artifacts are clearly a result of doing reflections in screenspace.
Small gaps in the reflection should probably look at nearby pixels (probably using a downsampled version of the screen) to avoid tiny ‘tears’ in the reflection (like those near the reed and the butterfly) rather than immediately defaulting to reflecting into the sky. This might also help with the noticeable triangle-shaped artifacts always present at the edge of the screen.
ROBLOX could also use environment maps instead or in addition to these screen space reflections.
Another option would be to use a lower-resolution render with a further clipping plane to do reflections. This could potentially cut out foreground features and allow water to reflect onto background features.
While we’re at improving reflections, we should probably at least have the option to have the same reflection effect apply to reflective parts. It shouldn’t be any more expensive to make it work with parts than terrain.