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Comment by kul_ | Hacker News Reader

I have never seen very realistic fire in any games! Is there a substantial challenge in fire simulation vs say water?

I think in part it's down to the fact that we want to interact with water - interactions with fire tend to be more incidental, and therefore there's less incentive to simulate or mock it up to a higher standard.

Thats not very convincing, I am sure setting fire to zombies would be fun!

I don't work in 3D graphics but it seems challenging to me because of the fluid dynamics. Fire is very low density gas rushing upward into the moderate density air - and even if you can do all the fluid dynamic calculations to render the boundary of the flame, you also have to render the light it's throwing onto the surrounding surfaces. I have no idea how close technology can come at this moment but I'm not surprised the answer is "not close enough for prime time".

Same for hair and cloth. Still got miles to go.

Something I've been meaning to find out for a while: we've all played with tearable cloth simulators in Javascript or HTML5. Surely game engines are more powerful than these, yet even modern games have cloth that doesn't move, stops bullets and can be stood on like it's concrete. Is it just not a priority/not worth the cycles?

It is easy to make something like that.

It is less than easy to interface something like that with a full game engine. Things like requiring collision culling (not doing the whole O(n^2) "check if A is colliding with B" thing), doing proper shadows, being properly deterministic, being alright with variable framerates, that sort of thing.

Also, I don't know what simulators you've seen, but the ones I've seen take an absurd amount of CPU time. Or occasionally GPU time. Works well for a proof-of-concept. But for a full game... Their priorities are elsewhere. Not worth the cycles.

That being said, I fully agree that game focus should be shifted slightly away from straight graphics and more into gameplay.

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