Weather

[matty47]

Just like to ask how others would implement things like

• rain or snow
• lightning - I have looked at Squats script but I think it only varies the light I am thinking more of a visible bolt
• sandstorm
• clouds

I presume the rain and sandstorm effects would need to be particles but would like to know how to achieve a wide coverage - is there such a thing as an emitter plane that would emit particles from each vertex? And how could I add a randomness like swirling?
I have played with the FX editor trying to obtain a lightning beam by using an emitter an beam object. I managed to get a  varying beam but the effect had a banding (areas with no texture)
I presume the best way to create clouds would be to use a billboard or simple cube with an appropriate alpha maped texture
Any constructive help would be greatly appreciated
Thanks
Matthew

[Steely Dane]

Rain or snow: Not sure. Theoretically, you could set up a null point with a string of emitters above, stretching out in front, and parented to the camera to give the illusion that it is raining or snowing everywhere the camera turns rather than actually raining or snowing on the whole "set", as it were.

Lightning bolt:  Well, depending on what your 3d app is, what you could do is extrude a single point polygon into a long chain of 2 point polys. Then use an animated fractal noise texture to displace the chain. Then export it as a scene.
You would have to add some luminosity and a glow effect as well. I have yet to import a scene into GC so I'm not sure if any of that would work, but I do know that's how you make lightning bolts in LW Layout......Anyway, you maybe could use a variation of that.

Sandstorm: Same as smoke I would assume, but you would probably have to set up a string of emitters somewhere beyond your far clip plain so as to give the effect that it's coming from somewhere off in the distance, coming from the direction that you have your wind set to come from, and give the smoke a sandy color. You probably wouldn't need to make it particles, as most sandstorms I've seen, (in films anyway) just look like big sandy colored fast moving clouds......throw a tumbleweed in there for yucks and voila'.

Clouds: Your idea sounds reasonable.

Just some suggestions, I haven't tried to implement any of these, and if they actually work, let me know.

[gekido]

most games use a full screen overlay to implement rain / snow - which could either be done as a custom post-process filter / shader, or as a simple poly with a surface animation applied to it and attached to the player.

[Squat]

I would go with the flat poly approach. Sort of a "personal skybox". You might need a special sequence or code or something becuase those shaders recognize that you're looking up and the overlay changes the direction of the rain.

In the end, however, it's impossible to create a local rain or snow effect without a random range for the particle spawns. Currently, we can emit from a single point in space at a time and that is inefficient and I believe very limiting in what we can accomplish with the particles. We should have radial distance for their source as well as a traditional x,y,z Min and Max values or it's not going to work for anything other than fountains and sprinklers.

[Steely Dane]

Good points, wasn't aware of those things as I haven't started messing with the effects yet.

The full screen overlay sounds like the way to go for rain or whatnot, but I would be curious to know if you can animate the texture on the skybox (like you can on flat planes), to give the appearance of rain in the distance as well, to give the whole effect some depth, not to mention adding lightning, with the bolts actually just a 2d animation on the skybox in the distance....roiling storm clouds, etc...

This wouldn't help if you actually wanted lightning to strike up close and personal.
I think my solution might be the choice your stuck with unless Gekido, Squat or any other of the magicians on here, has a better idea (an actual modelled and animated bolt with luminosity and a glow effect added).

The thing would be to remember is that lightning originates from the ground and shoots upward towards the clouds eventhough it looks to be the other way around (Clouds are turbulent mixtures of ice crystals, water droplets, and the icy seeds of hailstones. The negative charge of the seeds attracts a positive charge from the ground - they?ll reach out and try to balance each other with a flash of electricity? a lightning bolt ), and is usually just a quick flash, so you really wouldn't need to animate much other than it quickly forming, and reaching out from it's starting point (the ground) to it's ending point (the cloud).
I guess that all depends on how the new sky system with animated clouds looks and works...

[Squat]

I don't believe there is any solution to a really excellent lightning strike other than a polygonal model done how you said. It's crisper than any texture resolution you could try to cram in there and it's basically zero on the render times. You can also try additional material layers and use normal offset to help enhance the look.

[pixel_legolas]

a skybox or skysphere in GC can look really nice. You could build up a sphere with multiple spheres that have multiplied textures. You can animate each texture how you like with different speed. So you can have a sun texture on one, cloud on another, more dense cloud on next and a rain texture on another. That could make a nice sky.

Someone posted a Earth model with alot of layers animating in different speeds etc. looks very nice

[Steely Dane]

Is actually possible to animate it like I suggested (with a fractal noise texture, which is a procedural texture in LW) and save it out as a scene for export into GC?
If it is, that would open up a lot of other doors for effects, like electrical arcs between 2 posts for instance, kind of like the whole Tesla coil effects.....

[pixel_legolas]

nah, i think you can only use normal diffuse, normal, specular and glow. procedural stuff is not possible what i know

[Squat]

The trail FX works perfectly for arcs. It has arc, noise and everything.

[matty47]

Well I certainly can't complain about the help - all excellent ideas
Thanks

[gekido]

We added a new feature for the bolt effects as well for things like lightning guns etc - you can dynamically adjust the position of the bolt's end point - so for a dynamic lightning effect, you could have a static 'start position' and then have some kind of random position generated for the end point so the lightning jumps around etc.

having just moved to florida, we're getting some INSANE lightning that has been definitely giving me some interesting ideas for dynamic weather.  we definitely get alot of that ;}

[Steely Dane]

Dude, why on earth would you move from Vancouver to Florida? Not enough gangsters shooting each other here for you?  
Or are you just retiring early? 

[Squat]

I really like the idea of bolts of dynamic lightning. You can do the same thing by hand, but you'd have to manufacture the variation, this seems sweet. The one game that absolutely NAILED lighting, besides mine, is S.T.A.L.K.E.R. and it's due to the full scene shadows.

I hope there's plans for releasing a rain shader, or adding a range variation to the FX so that rain is possible. FX collision is also necessary. A world-space texture system would allow drops to splash and snow to cover the tops of things.

[gekido]

yeah life in vancouver became a little too gta for me - although the humidity down here takes a bit of getting used to ;}

arma 2 has some pretty sweet lightning as well.  basically lightning would be a combination of a beam type effect as well as lights - don't think that any single one 'thing' will do what you are looking for.

rain in the distance could be done using the animated uv settings that you can apply (under advanced surface proeprties / uv coords), just show / hide the distance rain objects as necessary.

most games that have rain don't have any kind of physics for the rain drops - what you see is a combination of effects - ie a full screen rain effect for up-close rain, distance cloud effects / lightning, and a seperate effect that gets spawned for the ground drops...use a small collection of raycasts to figure out random placement of raindrops, retrieve the normal & intersection point and spawn mini 'splash' effects on the various objects.