Afterburn -> normal map?

Eric Chadwick · Sep 2006

Anybody ever tried to create a tangent-space normal map for clouds?

I'm wondering if Afterburn (volume particle plugin for Max) could be lit properly by directional lights, so it could be rendered into a normalmap? I don't have it here to test.

I was thinking of using this old trick for lighting the scene, so the front view can be rendered into a tangent-space normalmap...

I tried converting a DarkTree procedural into a heightmap, and then into a normalmap. Looks ok, but the volume isn't very convincing.

Anybody try a normalmapped cloud plane?

ScoobyDoofus · Sep 2006

That seems pretty clever, but I've always been told that transparency with normal mapped surfaces is prohibitivly expensive....

CrazyButcher · Sep 2006

scoobydoofus: only when lots of light affect it, if its just one (say sun for the clouds) it should be no problem to render in one pass

wondering what would "render elements" when rendering such a particle return ?

cool idea with the lights.

Eric Chadwick · Sep 2006

It isn't too slow for what I'm doing, works OK.

Messing with parallax right now, kinda cool since it adds a swirly/billowy animation to the clouds as they pass overhead. But the swirlies also cause some ugly banding, not happy with it yet.

Anyone have Afterburn and willing to do a lighting test for me? I'm curious if it lights well with multiple pos/neg lights.

conte · Sep 2006

EricChadwick
haha, smart.
Can show example? it will be interesting to see.

J.I. Styles · Sep 2006

second time today I've forgot to copy my post before submitting, and having the forum chew it up

I did a write up, suffice to say I've tackled this problem before and it's hard - you need to strike a balance between ripping a normal where you're able to see through the volume density, and a solid volume that retains its shapes lighting. Shadow of the colossus did it quite well in the end.

here's a quick example (no way near perfect)
http://jistyles.com/content/temp/forum%20images/cloudnormal.tga

Eric Chadwick · Sep 2006

Thanks for the testmap Joel. You're right, transparency needs careful massaging. Going to take another look at SOTC, didn't notice that, thanks for the pointer.

Here's what I have so far. Ditched the parallax, it was too messy. These are using a normalmap, a wide orange specular, and some cubemap diffuse lighting (for the backshading).

Still lots to go, not real happy with the shapes.

(edit.. added thumbnails)

Eric Chadwick · Sep 2006

Getting closer. Kind of looking more like terrain than clouds though. Using parallax now, but it's real sensitive, seems to require lots of small tweakage. Looks good in motion, even though it's a simple UV scroll.

Joshua Stubbles · Sep 2006

The game Lock On:Modern Air Combat uses normal mapped clouds. If I get the chance to reinstall it tonight, I can post their cloud texture for ya.

Eric Chadwick · Sep 2006

Hey thanks Vassago, yeah I'd like to see that.

I'm not happy with any of the clouds I've seen people make with Afterburn. Looking into Dreamscape today, maybe its patterns will be better.

J.I.Styles, did you see the SOTC clouds move? Or are they just in the cubemap?

<edit> Some good pics here of Lock On. Looks like a combo of unlit sprites and nice-lit cloud decks.
http://games.tiscali.cz/clanek/screen.asp?id=1145&a=1

Would love to see the nrmlmaps/colormaps they used for both their white puffies and their overcast.

SHEPEIRO · Sep 2006

i love effects work, really lets you put alot of love into simple, yet trixsy elements.

i think the major prob with yours eric, is that the detail is too strong, givving it too much of a landscape feel, make the volumes stronger and reduce the effect of the detail.

also detail is a bit regular, maybe some mixes between sizes of deatil, or some hand painted aditions might make them better.

almighty_gir · Sep 2006

instead of rendering out the maps using coloured lights, why dont you do each direction at a time in grayscale, and use those as your RGB channels?

wouldnt that give you a lot more control over the final output?

Eric Chadwick · Sep 2006

Well, as always, I've had to shift focus onto something else.

Good ideas Shepeiro.

almighty_gir, same thing really, just the colored lighting is easier/faster.

arshlevon · Sep 2006

i also think the shader has a good deal to do with it, clouds are really fluffy and absorb tons of ambient light making them almost glow, right now they have a very solid hard matt material that looks like stone. this is really interesting, i kind of want to try something similar with crazy bump, cause i havent really got to mess with it yet.

Sage · Sep 2006

Hi Eric I kind of like the shape of your clouds but the textured part just seems too hard and not soft and fluffy. Here isa quick attempt. I set the shader transparency to additive and that softened the effect a lot the downside was that it made too bright. I just painted the normal map in photoshop and embossed it 4 times top, bottom, left and right. Then processed the layers with the nvidia filter. Let me know what you think.

Clouds without the additive filter.

cloud normal map

Eric Chadwick · Sep 2006

Yeah I agree with both of you, I think my textures are too fractalized, harsh.

I think you're going in the right direction Sage. Thanks for posting this! I think it's looking a bit clumpy, too uniform, too thick. I thought J.I.Styles and arshlevon had the right idea about needing some luminosity.

I'm shooting for something like low-level fractocumulus, or stratocumulus...

I'd love to get cumulus mediocris, but I don't think that's achievable with a single shader scrolling across a flat (or arched) geometry.

My clouds have to work well with a moving sun, sunrise/noon/sunset/moonlight, that kind of thing. And I want it to look like wind is slowly pushing them across the sky.

Anyhow, on a couple other projects right now. Hope to get back to this soon.

Vassago, didja ever get a chance to install it?

CrazyButcher · Sep 2006

http://crazybutcher.cottages.polycount.com/wip/skymeshshaderfull/

I also did some work on dynamic skies, though it has no normalmap use, but I will come back to it once the other effects are done and do a "second pass" on the effects with some pixel shader use.

but faking the "height" of the clouds while still just flat is gonna be hard

Afterburn -> normal map?

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