[Haskell-cafe] How to model outer space for a MUD

Tikhon Jelvis tikhon at jelv.is
Fri Aug 14 22:36:17 UTC 2015


The problem with just modeling things is that certain questions become
difficult. For example, it's often useful to know what thing is closest to
some given thing, or what a thing's closest neighbor is.

Moreover, while there is certainly a lot of space out there, this is
Haskell so we can model all of it lazily. That's what Conal's blog post is
about: a practical way to lazily model images with no bounds and no
resolution limit.
On Aug 14, 2015 3:31 PM, "Jeffrey Brown" <jeffbrown.the at gmail.com> wrote:

> I would not model space -- there's too much of it -- rather Things in
> space. Each Thing has a 3d coordinate (plus more geometric information,
> plus more information). Things can be rooms, and things can have position
> defined in terms of other things.
>
> On Fri, Aug 14, 2015 at 3:23 PM, Michael Litchard <michael at schmong.org>
> wrote:
>
>> Well, thinking more about it, I think I want an 8-regular complete graph.
>> I've been doodling and came to the conclusion pretty quickly that thinking
>> of this space in terms of a grid wasn't quite right. I *would* like to only
>> hold data of populated nodes if possible, to model an infinite space as
>> David mentioned. I've been looking at fgl to help me think about this
>> problem in terms of a graph. I'll think and tinker over the weekend and see
>> if I can come up with something more articulate. Not committed to a graph,
>> but I want a discrete structure and this looks like it fits the bill at the
>> moment.
>>
>> On Fri, Aug 14, 2015 at 2:00 PM, KC <kc1956 at gmail.com> wrote:
>>
>>> I agree with Tikhon
>>>
>>> But a sparse matrix might be conceptually simpler to start with
>>> But are sparse matrices easy to implement in Haskell and then is it easy
>>> to change the data structure layer on?
>>>
>>> --
>>> --
>>>
>>> Sent from an expensive device which will be obsolete in a few months! :D
>>>
>>> Casey
>>>
>>> On Aug 14, 2015 1:50 PM, "Tikhon Jelvis" <tikhon at jelv.is> wrote:
>>>
>>>> It depends on exactly what you want to represent and how you want to do
>>>> it.
>>>>
>>>> The first thing that comes to mind for me would be using an octtree[1],
>>>> which is the three-dimensional analog of a quadtree[2]. Conal Elliott has
>>>> an interesting point about using quadtrees to represent images in
>>>> Haskell[3], and you should be able to adapt the idea to indexing into a
>>>> three dimensional world with an octtree.
>>>>
>>>> [1]: https://en.wikipedia.org/wiki/Octree
>>>>
>>>> [2]: https://en.wikipedia.org/wiki/Quadtree
>>>>
>>>> [3]: http://conal.net/blog/posts/topless-data
>>>>
>>>> On Fri, Aug 14, 2015 at 1:44 PM, David McBride <toad3k at gmail.com>
>>>> wrote:
>>>>
>>>>> If you are thinking of it as a 3d grid, you might just have a (Map
>>>>> (Integer, Integer, Integer) Contents, where every room in this 3d grid that
>>>>> has something in it is in the map and every room that is empty space has no
>>>>> corresponding entry in the map.
>>>>>
>>>>> Then when you enter a room you can quickly look up what is in that
>>>>> room, then reasonably quickly check the neighbors in every direction to see
>>>>> what the ship might be able to sense were it to travel in that direction.
>>>>>
>>>>> In this case, space is infinite, but the datastructure is only as big
>>>>> as the amount of content you have.
>>>>>
>>>>> On Fri, Aug 14, 2015 at 4:34 PM, Michael Litchard <michael at schmong.org
>>>>> > wrote:
>>>>>
>>>>>> Star Wars MUD has a 3-D coordinate system such that (0,0,0) is some
>>>>>> planet. I'm curious as to how one might model this system that could
>>>>>> simulate a ship's movement through a 3-D grid. Matrix, 3-D array, graph.
>>>>>> None of these? Ideas?
>>>>>>
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>>>>>>
>>>>>
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