Monday, April 7, 2014

VFX Tips - Making Smoke Textures

I was playing Space Marine the other day, and I was interested in the way they handle their smoke textures. The textures aren't animated as far as I can tell, and manage to get a lot of mileage without needing too high of a particle count.

I decided to try painting a smoke texture similar to the ones they used.

First I painted a brush to use to make the body of the smoke.

I made it out of a gradient circle brush and the smudge tool. I set it to use a bit of scatter, random angle and size, and a dual brush with a gradient circle to help unify the edges while painting.

I painted the general shape of the smoke with the brush.

I always like the paint on a midtone color because it gives you a better idea of what it could look like ingame. I then dropped the cloud I painted down to a dark tone.

They layed on highlights using a soft brush.
I then added a bit of darker value to help separate the cloud shapes more.
Then added a brighter highlight to better define the edges.
I slightly overlayed some photos of real smoke to add a bit more internal noise, and made the whole thing a slight tone of yellow (giving a texture some internal color differences can help your effects not look so uniform when colorized)

Now perhaps the most important thing to consider when making a smoke texture is the alpha map. You want to break up your alpha map as much as you can. Give it a lot of gaps and turbulence in the texture. You want to do this because when you have a particle fade out in a particle system, less of the detail is defined by the diffuse texture and is instead defined by the alpha texture, so if your alpha is a big opaque blob, that's what it's going to look like at a low alpha.

Good alpha map...
...Gives good results!

Bad alpha map...

... Gives bad results :(

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