Rain - The wet look

[Flexman]

What's the general approach to achieving the "wet look" with a deferred renderer? Making rain particles is straight forward, I'm interested in objects/terrain.

 

Here's a Unity Plugin video that is sort of the look I'm after...

 

This would be nice too, although I shudder at having to supply yet another texture map for materials to achieve this. This is an image from another rendering system that has a nice puddle/wet effect.

 

 

I'm thinking one might create in Photoshop a tillable 'render cloud" image that could be used as a specular mask. Any thoughts?

I added a specular modifier to the terrain shader which isn't too bad, with particle rain and SFX it's not too shabby but not great either.

[wailingmonkey]

perhaps consider affecting the normal as well in coordination with the specular?

(thinking puddles tend to wash out --sorry for pun-- the bump detail they're sitting on top of...although

I do like the gradient effect of the second image around the shiny edges--the puffy outer edge

seems off though)

 

Seems like you'd definitely need multiple UV-channel support for anything affected by your rain shader.

 

(I'd guess there is probably a UDK shader example out there somewhere too)

[Richard Simpson]

Test Drive Unlimited 2 has a nice wet look to their roads. Not sure how they do it though.

[Josh]

It's possible to do this with a post-processing shader that perturbs the normals using an animated texture and a calculation of the surface normal.

[Naughty Alien]

..masked cubemap+normalmap(animated rain drop) will do just fine..

[Flexman]

..masked cubemap+normalmap(animated rain drop) will do just fine..

 

OK that makes sense. This would need to be applied to every exterior material when it rains.

 

It's possible to do this with a post-processing shader that perturbs the normals using an animated texture and a calculation of the surface normal.

 

Sounds too easy, I bet there's a catch. Besides my shader programming isn't savvy enough to do this in a reasonable amount of time but the principle seems sound.

[Josh]

You just get the world position and normal of each pixel, round off to the nearest XZ direction (there are four possible). Use that for the vertical component of rain sliding down. Then add in raindrops based on the Y component of the normal. You can do something similar for snow accumulation...someone posted a video of it working.

[Gandi]

and how would you solve the problem with no raindrops in the interior or where raindrops just shouldnt hit (under a table).

 

i don't know which engine it was, but there was an engine which implemented it as a light type (don't know how far thats possible in LE). But if you dont care if it rains under your objects or in the interor a post process shader should do the trick pretty much.

[franck22000]

It is the CryEngine3 Gandi

[Josh]

I think you are thinking of STALKER, they called it a "rain shadowmap". That's just it, you do a depth render to a texture, then use that in the shader to tell where the rain is allowed.

[tournamentdan]

You just get the world position and normal of each pixel, round off to the nearest XZ direction (there are four possible). Use that for the vertical component of rain sliding down. Then add in raindrops based on the Y component of the normal. You can do something similar for snow accumulation...someone posted a video of it working.

 

I think you are talking about this video. http://www.leadwerks.com/werkspace/topic/3410-real-time-snow-accumulation/page__view__findpost__p__31134