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Does Crysis 3 have a volume texture cover the entire level for particle turbulence?


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#1 Sock5   Members   -  Reputation: 162

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Posted 04 May 2013 - 08:55 PM

For my particle systems I'm using a relatively small 3d texture that pretty much stores the info about the turbulence field around the particle system.The issue with this is that it has a limited size(the confines of the particle cloud), so it wouldn't take too much memory and that it is kinda slow to update from the application(at least for me), and it gets problematic when I have a lot of particle systems running at the same time, but in Crysis 3 the vegetation/particles/cloth react everywhere, also the nex APEX(or whatever it's called) system for particle turbulence seems to not suffer from the limitations I experience.So how do they do it?Even with cascades, to get that fine effect from the videos at close range, you would need a gigantic texture and they even had multiple particle systems mixing around at close up blink.png .Any ideas?


Edited by Sock5, 04 May 2013 - 09:46 PM.

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#2 Bacterius   Crossbones+   -  Reputation: 8886

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Posted 04 May 2013 - 09:55 PM

Are you sure they don't calculate this on the fly based on some procedural approach?


The slowsort algorithm is a perfect illustration of the multiply and surrender paradigm, which is perhaps the single most important paradigm in the development of reluctant algorithms. The basic multiply and surrender strategy consists in replacing the problem at hand by two or more subproblems, each slightly simpler than the original, and continue multiplying subproblems and subsubproblems recursively in this fashion as long as possible. At some point the subproblems will all become so simple that their solution can no longer be postponed, and we will have to surrender. Experience shows that, in most cases, by the time this point is reached the total work will be substantially higher than what could have been wasted by a more direct approach.

 

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#3 Sock5   Members   -  Reputation: 162

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Posted 04 May 2013 - 10:13 PM

Are you sure they don't calculate this on the fly based on some procedural approach?

yeah here's a reference video, at 0:49 they show wireframes of the "turbulence nodes", but as you can see they can stretch infinitely as long as the particle trail is, so if the character goes very fast, they can stretch the entire room, not to mention there are multiple such systems running at the same time.Also notice the fine detail at 1:15 and later on, it has to be some really dense field/grid...

(I used an Unreal Engine video, cause the Crysis 3 videos don't show it mich, it has to be seen in-game, but I think it's the same concept)


Edited by Sock5, 04 May 2013 - 10:17 PM.

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#4 Hodgman   Moderators   -  Reputation: 30388

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Posted 05 May 2013 - 12:41 AM

With APEX, they might not be using a grid at all to store/propagate turbulence, it could be using something like SPH instead. If so, SPH requires each particle to inspect the state of it's nearby neighbours, so they would likely use a grid to accelerate the neighbour search. However, this grid could be built from scratch every frame, with a different size each frame. Each frame, they could use the bounding box of the particle system as the bounding region of the grid, so that as the particles occupy a larger space, the grid cells simply increase in size to accommodate it. This wouldn't change the behaviour of an SPH system at all, it would only decrease the efficiency of the neighbour search in dense areas.

 

With crytek's foliage, etc, I'd guess they're using procedural turbulence effects. e.g. an explosive creates a spherical force emitter, which points can test themselves against over time to calculate the forces imparted on them.


Edited by Hodgman, 05 May 2013 - 12:44 AM.


#5 InvalidPointer   Members   -  Reputation: 1433

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Posted 06 May 2013 - 11:40 AM

Grass recieves special treatment in Crysis 3-- a 16x16x16 turbulence grid centered on the player, IIRC, but as far as I know common vegetation still uses something like this for procedural animation. Objects have a wind vector/time value, and sub-object detail is all shader trickery.


clb: At the end of 2012, the positions of jupiter, saturn, mercury, and deimos are aligned so as to cause a denormalized flush-to-zero bug when computing earth's gravitational force, slinging it to the sun.




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