Comments on: How To Make a “Falling Sand” Style Water Simulation http://w-shadow.com/blog/2009/09/29/falling-sand-style-water-simulation/ Slightly Advanced Computer Stuff (and some magic) Thu, 18 Mar 2010 17:05:30 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: White Shadow http://w-shadow.com/blog/2009/09/29/falling-sand-style-water-simulation/comment-page-1/#comment-31619 White Shadow Wed, 30 Sep 2009 13:14:58 +0000 http://w-shadow.com/?p=1295#comment-31619 You are correct, updating bottom-to-top is a good approach. I didn't mention it in the post, but that's exactly what my demo app does. However, that alone wouldn't be enough to prevent "teleportation" in a more complex simulation. For example, if you added a rule like "if this fluid particle has another fluid particle above it, move this one sideways" (i.e. a very basic pressure factor), you'd get particles teleporting left or right depending on the direction of your X loop. So tracking which particles have been updated still makes sense. You are correct, updating bottom-to-top is a good approach. I didn’t mention it in the post, but that’s exactly what my demo app does.

However, that alone wouldn’t be enough to prevent “teleportation” in a more complex simulation. For example, if you added a rule like “if this fluid particle has another fluid particle above it, move this one sideways” (i.e. a very basic pressure factor), you’d get particles teleporting left or right depending on the direction of your X loop. So tracking which particles have been updated still makes sense.

]]> By: Ross Shannon http://w-shadow.com/blog/2009/09/29/falling-sand-style-water-simulation/comment-page-1/#comment-31618 Ross Shannon Wed, 30 Sep 2009 13:00:31 +0000 http://w-shadow.com/?p=1295#comment-31618 Good tutorial, thanks. I don't understand the problem with particles teleporting downwards though — it seems to be that the only reasonable way to program this is to do the simulation updates bottom-to-top. Otherwise, if you update top-to-bottom, when you update the game state array, any particles that have another particle above them will be overwritten by the top particle falling into their position? Good tutorial, thanks. I don’t understand the problem with particles teleporting downwards though — it seems to be that the only reasonable way to program this is to do the simulation updates bottom-to-top. Otherwise, if you update top-to-bottom, when you update the game state array, any particles that have another particle above them will be overwritten by the top particle falling into their position?

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