Wet surface

[maximsubbota]

Hi, im working in a rain system and I need help to simulate real wet surfaces.
I tried to use specular masks but it looks metallic but not wet.
Help me if anyone knows.

Secundary petition.
I want to know, how can I simulate the rain drops collision effect sinchronized with the collision location of the rain drop.

sorry for my bad english. Im from spain.
Thanks for your help

[mikesdk]

I think what you need to do for the wet surface is overlay a cubemap reflection on it. It's pretty advanced material work but when you pull it off it looks amazing. Unfortunately I don't know enough about material construction to help you achieve it.

[Analdin]

What also looks good (only on distorted surfaces like concrete or asphalt) is the "Specular Power" node. It makes the material look dripping wet if tweaked right.

[maximsubbota]

I tried the splecular mask, and specular power, but it looks metallic, not wet..

[mikesdk]

Did you set the power high or low? For non-metallic surfaces you'll want to keep the specular highlight as broad as possible, so a low number. I believe the default is 15.

[maximsubbota]

With specular mask I think is possible to create wet surfaces but I want to create a more realistic effect as in stalker
http://www.youtube.com/watch?v=Dq1Y7m4ahFs
http://www.youtube.com/watch?v=GVBiF-hlkso

[Sir. Polaris]

To my knowledge, S.T.A.L.K.E.R used a "Rain layer" which told the internals how it was to react with the surface it was on. At which time a panning texture, specular and normal map was added to simulate flowing water on surface.

The rain drop emittance and splashes - I cannot remember (or was never told/read) how they occurred. I know it was all done with a 'layer' just like you would do thermal or any other "how much should I affect a thing" mask.

[mikesdk]

As far as I can tell from the video, this is done entirely with specular and normal mapping. This being said, I am far from an expert on materials, but I am learning, and getting a better understanding of the underlying techniques.

The thing to remember about specular power is that the higher the number, the tighter and smaller the specular highlight will be, and the shinier the surface will appear. The lower the number, the broader and more flattened out, so to speak, the more wax/wet like your surface becomes.

I suggest you post a screenie of your progress so far, so we can help determine the solution.

[maximsubbota]

the problem is it that I dont know how can I simulate rain, I had the particle sistem but I dont know how can I sinchronize the drop spashes with the same drop location.
the question is, how?

[Hitpawz]

As far as I know right now, there is no way to have a paticle spawn another particle. While it may be possible, I haven't seen any evidence of it yet.

To truly simulate rain you're going to have to get into code as I can't see any way around it. You'll need to do a trace from random positions straight down to get the position of each drop and its falling distance. It will need to spawn a particle down that trace and then detect that it's hit the ground and spawn an animated decal of a distortion ring aswell as a particle splash. Probably you're going to simply need to spawn a tiny invisible object with a collision sphere. This object will call the rain drop particle event and will detect its collision with the ground.

The other way to do rain is to simply fake the living hell out of it and not worry about drops aligning with splashes. You can create a material using a texture sequence generated in an external program for distortion rings. I'm relatively certain the material system can be worked to get these to show up only on the tops of objects in world space. The raindrops can be sheets of meshes interlocking with a panning texture of dozens of raindrops.

In all honesty, in real life you cannot detect a single drop's entire range. We all KNOW what is happening, but you don't see a particular drop fall from the sky and then actually track its entire path down to the splash on the ground. You might think you do but the transition from looking up, to looking straight, to looking down causes your eye to lose focus and tracking ability and what you see are different drops at those different vantages. So don't worry about it all lining up perfectly, just get the 3 elements working.

By the way, rain and water specular highlights are extremely high powered in the range of 15 to 30 such that there are tiny speckles of light, not a broad overlaying sheen. The broader the specular highlight, the dryer and more matte the material. Metal is a highly sheened material so the highlight is tight, but MUCH broader than if the surface is wet. Also, the diffuse is 15-20% darker than when it's dry.

Lastly, distortion only works on objects which are transparent and affects the pixels behind the object, not the object itself. With that, you're gonna have to offset another copy of the mesh or at least a flat plane if you want to distort the object itself.

[JamieG]

Lastly, distortion only works on objects which are transparent and affects the pixels behind the object, not the object itself. With that, you're gonna have to offset another copy of the mesh or at least a flat plane if you want to distort the object itself.

... or distort the UVs instead

[maximsubbota]

thanks for all!.
I have the last question,
how can I create thunder storm (lighting effects) like these?

[obihb]

Here's how you can get drops to splash with a particle system.

In the shot included you see on the 1st system you have a collision node and an Event Generator with collision as the type of event. The collision node has a setting you can set it to kill. So the 1st system particles will die on collision and execute the event. On the 2nd system you have the receiver as a Spawn receiver. You link them with a name, which I used as DropSplash. In the spawn node you see Constant 5, which is the amount of particles getting spawned.

Just a simple example but hope this helps you with the rain drop splashes.



Uploaded with ImageShack.us

[Sir. Polaris]

By the way, rain and water specular highlights are extremely high powered in the range of 15 to 30 such that there are tiny speckles of light, not a broad overlaying sheen. The broader the specular highlight, the dryer and more matte the material. Metal is a highly sheened material so the highlight is tight, but MUCH broader than if the surface is wet. Also, the diffuse is 15-20% darker than when it's dry.

This is really good to know information. Is this a educated guess or pegged information based from somthing?

[maximsubbota]

thanks a LOT obihb, and thanks to all for the help!
I have all that I need, but I last one I want to know how can I make a thunder storm with kismet. If anyone knows, please, help me

EDIT.
I made everything but I have a problem, the rain density its low and if I change the spawn amount my particles comes in waves.
the question is, how can I change the density of the rain without changing lifetime.