we had the old rain in the old world editor. like rain snow thunder storms or dynamic weather. instead of just the maps it would be under environment?
A full-stop weather system would involve a lot of individual parts working in concert. Assuming you only want to simulate rain and thunderstorms, and don't need the weather to be localized to certain areas of the map, here's everything you'd need or want, ranked by how easy it is to implement: Precipitation particles. Basically just 2d billboards of raindrops, generated by a particle system linked to the current viewport (wherever it might be located). Already in the engine, and it works pretty well. The biggest drawback is that precipitation particles do not collide with anything, so rain will still appear in tunnels, under bridges, and in vehicle interiors. Raindrops used to be able to collide with the surrounding environment, but that feature began to create performance issues and had to be removed, iirc. Dynamic environment variables. This is already implemented, as clouds can be spread out across the sky, forest wind emitters can be dialed up, sunlight can be made darker and shadows made brighter to make the light seem more diffuse. A second light could even be rigged up to simulate lightning (a light animation does exist, but sounds and visuals don't). The only thing not currently as fluid is fog. While fog values can be set at runtime, it's not a smooth transition: setting denser fog to fake dense rain will happen abruptly, not gradually. Dynamic materials. The ability for roads to look more wet. There might be ways of altering single materials at runtime using code, maybe even Flowgraph, but altering nearly every material at once sounds like it would be a nightmare using such a method. PBR has given the materials a lot more latitude to express what's going on with the surface, but currently there's no easy way to put this into practice. Would also be set per-material, so even roads in tunnels would appear wet. Dynamic surface friction. The ability for roads to physically "act" more wet after receiving enough precipitation. Asphalt gets more slippery and stops producing tire tracks, dirt turns to mud, etc. Was previously implemented (and in some tests of mine, worked well enough for realtime weather), but has since been removed, possibly due to subsequent work on tire physics. Accumulation and water body swelling. Rainwater pooling in dips and ditches, and causing rivers and lakes to overflow. Currently, dynamically moving rivers and water blocks does not work too well. Just like with fog, they can be relocated at runtime, but can't be moved smoothly, and some of them may be specifically positioned such that moving them might cause you to see the water's hard edge. More importantly, water blocks, water planes, and rivers deal with water differently than wet surfaces (such as the ones in ETK): the fluid simulation just isn't there for the latter to smoothly transition into the former. And even small puddles forming would require either another heightmap for the landscape, to dynamically add water into specific spots, or the game to calculate where water would accumulate, and add the needed decals to make it look wet. Ultimately, it would come down to either more work for the map designers, or much more work for the game engine. Surface raindrops. Raindrops forming trails on car bodies, windshields, etc. Possible using some complicated math and such, but not even on the radar yet. All told, bits and pieces of this are possible, but without the full package, anything more than a light sprinkle is just not polished enough to be worth the while yet.
If dynamic materials prove possible and dynamic surface friction would return, it should be polished enough to happen, at least as a mod. But as it stands, even night time isn't rounded off fully.
