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Thread: What am I aiming for in the cell structure of the map?

  1. #1
    New Member
    Registered: Feb 2019

    What am I aiming for in the cell structure of the map?

    Hello TTLG,

    I have been working on a map for a few months now, recently I decided to do a little extra reading into DromEd and NewDark, now I've been going around what I've made with show_cells enabled.

    Clearly, there is some dodgy looking stuff in what I've made. I've had some success in correcting what looked bad, a lot of seemed to do with air brushes intersecting cylinders. I am also vaguely there are some restrictions on the kinds of architecture that works well in DromEd, though don't know what those are exactly.

    The thing is, I have no idea what cells are for, and what are the red flags / bad practices in cells. All I know is there is a maximum limit. Like, for instance ...


    This looks less than ideal to me.


    But are the cells in this doorway bad?

    Can someone enlighten me on the best approach to dealing with cells? Or point me towards a tutorial I've missed.

    Thanks

  2. #2
    Member
    Registered: May 2017
    Location: USA
    Cell limit is around 32000. Indeed, cylinders are a bit “greedy”, and you can often achieve the same structure with fewer cells using wedges. Take a look at some of Skackys missions in dromed. He’s a master of pushing dromed to its architectural limits.

    However, if dromed isn’t complaining, I’d just keep doing what you’re doing. Unless your plans are pretty ambitious, planning around the cell limit probably isn’t needed.

  3. #3
    Member
    Registered: Apr 2011
    Location: Montpellier, France
    The limit is 32760.
    I don't know all the inner workings of the engine, but cells is pretty much the way the engine splits faces on polygons. If you want to keep cells in check it's important to avoid using too many air brushes, especially complex air brushes such as cylinders with many faces. Protruding bits of geometry also increase cells, such as trims that aren't flush with walls. With NewDark the cells limit is the one you're most likely to reach first, but if you're not planning your mission to be a behemoth of size and complexity there's no real reason to worry too much about it.

  4. #4
    New Member
    Registered: Feb 2019
    Thanks for the replies! I think they pretty much explain everything I wanted to know.

  5. #5
    Member
    Registered: Jan 2001
    Location: Formby, NW England
    My description of cells is that they're the 3d space that's generated by portalizing or optimizing (the latter of the two usually reduces the number of cells/polygons in any given area).

    The strangely shaped cell in the first screenshot is only a problem if the AI consistently struggle to navigate around or through it. Navigation problems may be helped by using a 'blockable' brush, which changes the arrangement of cells that intersect it.

  6. #6
    Member
    Registered: Sep 1999
    Location: Austin, TX
    Quote Originally Posted by skacky View Post
    ...Protruding bits of geometry also increase cells...
    DIAMONDVEHICLE: Sometimes this is hard to avoid to make interesting architecture, however if you can, try using objects for these details, this will save you such cells. The community is good at making custom objects (often asked for here https://www.ttlg.com/forums/showthread.php?t=129765), and a cuboid would be super easy. I can pump some out, just name the DU dimensions you need, and send the texture that would fit in your mission. If I'm wrong about texture size, you can mod it using a MTL file - which I can help you with. But as said, you may be okay anyway. Just optimize to see them cut down, then also you can use blocking brushes touching a surface that's really spiderwebbed with cells.

  7. #7
    New Member
    Registered: Feb 2019
    Thank you so much for all this extra info.

    @R Soul ... I had been neglecting Optimise this whole time. That just halved my cell count...

    @gamophyte -- I really appreciate that offer. Like you say, I'm not sure if it will be necessary. My cell count is looking a lot better now than it was.
    If my level gets to the stage where I need that level optimisation, I may get back to you. If the offer is no longer available then's that fine

    My pessimism about cells has been a bit of a blocker for me in terms of motivation, so I can't overstate how useful this thread has been.

  8. #8
    ZylonBane
    Registered: Sep 2000
    Location: ZylonBane
    IIRC, one of the original Looking Glass documents that came with DromEd included an extensive section on minimizing cell splits. I'm not sure where to find it though.

    As for what cells actually "do", that's explained in detail here: https://nothings.org/gamedev/thief_rendering.html (TL;DR, they're used to calculate visibility when rendering)

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