# [Haskell-cafe] Representation of 3-D objects in non-continuous space

Michael Litchard michael at schmong.org
Sun May 22 18:08:20 UTC 2016

```I mean, I could only find ones with bounding rectangles.

On Sun, May 22, 2016 at 10:57 AM, Michael Litchard <michael at schmong.org>
wrote:

> I've been poking at the problem that I've talked about in the following
>
>
>
>
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> And my misguided conclusions here
>
>
> I'm trying to write a clone in haskell of the space-system implemented in
> http://swmud.org.
>
> The biggest error in my thinking so far is assuming I could do without
> spatial extent.
> Nope, these objects in space will have to have spatial extent. So no
> octree for me.
> investigate R-trees.
> I could only find specifics about how to describe 2-D.
> Until I found this paper on layered R-Trees.
>
>
> http://www.isprs.org/proceedings/XXXIII/congress/part4/1216_XXXIII-part4.pdf
>
> This looks like what I want. Here's my re-formulation of the criteria:
>
>
> (1) Objects in space will be either ships that can move or stationary
> things like non-moving game-controlled ships, space-stations , moons and
> planets.
>
> (2) Objects will have spatial extent. Will use bounding volumes to help
> determine collisions.
>
> (3) Space is non-continuous
>
> (4) Movement happens by setting a destination vector and a speed. There's
> no steering exactly, but you can change destination while moving, slow down
> or stop suddenly.
>
> (5) Represent this space with a layered R-tree, This tree will at most
> have say, 200-300 objects in it, most of which could be moving around in
> this space.
>
> It's the number of objects that have me wondering if layered r-tree might
> be too heavy-weight.
> If so, Any links to R-tree variants that include bounding volumes? I could
> only find ones with bounding boxes.
>
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