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rouncer

unlimited detail

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I was thinking about unlimited detail, and the main thing that baffles me is how can they instance so many rocks, theres one rock for every grain of sand, the amount of instances would blow the ram itself, If you wanted to do it with the gpu then youd get a huge draw call problem... anyone else have an idea about this aspect?

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Ugh, it's been discussed on here before. They've been trying to sell their tech for over 10 years now.

The point of instancing is that it doesn't take up much RAM. One rock at high detail takes up a lot of RAM, and then each instance of that rock only takes up a few dozen bytes -- this is why their demos are made up of the same pieces repeated over and over again.
Also, they don't instance grains of sand -- they've have a model of some sand, covering, say a 5m*5m area, and then they instance this model many times.

As for the GPU, they're not using the GPU - they're performing a kind of ray-casting on the CPU - akin to tracing a frustum through an oct-tree until you find a solid leaf node. When they port it to the GPU, they'll likely still be performing ray-casting instead of drawing batches of polygons (as "no polygons" is the whole point), so DrawCall counts aren't a problem.

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not that I like their marketing style, its just I find the fact they seem to be able to instance so much kinda useful... so theres nothing really magical going on here? Its just if I went to do this id surely run into too many draw calls... but imagine the power of being able to replicate things on such mass, would be kind of useful.

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GPU's support a variety of techniques that go under the umbrella name "instancing", which allows you to draw thousands of instances of a mesh in a single draw-call.

The specific kinds of instancing that you can use depends on which graphics API you're using.

Some random google-results on the topic:
Efficiently Drawing Multiple Instances of Geometry (Direct3D 9)
http://www.rastertek.../dx11tut37.html
http://software.inte...-in-directx-10/
http://www.slideshar...get-started-now
http://www.slideshar...n-battlefield-3
http://en.wikipedia....etry_instancing

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It seems they are using an octree data structure. If that is the case, they have only one octree node with the elephant data stored in and then many octree nodes from around the level have that same node as a child. The elephants and trees and all stuff is perfectly aligned if you have noticed, and the level feels like it is made of tiles. This suggests a monolithic octree structure with like 10 "real" nodes that each has 30000 parent nodes pointing at it. If you want to look at a serious attempt at voxels google Atomontage engine. UD is a scam and Bruce Dell is full of crap.

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