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  1. #1
    Join Date
    Jan 2003
    Location
    Brisbane Australia
    Posts
    1,525

    "where did these holes come from?" tutorial.

    I have seen a lot of questions lately, "where did these holes come from?", "there is a hole in the wall?", "somthing is blocking me?", "I cant line my brushes up on the grid?". If you have said one of these things or somthing like it then keep reading.

    So hopefully Im going to write a quick tutorial on how to fix all these things.

    All these things are actually related to the one thing, messy BSP.
    What is messy BSP you ask? In the picture below is of 4 brushes blue, pink, green, yellow. looking from the top view.
    and in the orange is some nasty bsp holes.




    Now in the next pic is a closeup of the corner where blue green and yellow meet. All these lines should meet and not overlap. this is what i call messy bsp, the lines are all over the place.



    What we want to do is get them sitting back on the grid. To do this set the grid to 1 click the vertex editing button
    In the Top viewport left click on one of the lines to select the brush. then hold down ctrl + alt + click and drag with the left mouse button on the corner of the brush so that the point is inside the red box, like in the picture below. Or you can simply left click on the point you want to select.


    Now the point should be white this means that it is selected. If you have more than one selected hold ctrl + right click on one of the points to deselect them.
    Once you have a point selected righ click on it with the mouse. This will snap the point back to the nearest grid. Continue to do this to the remaining brushes and points until they are all back on the grid, See picture below



    Now do the same in in the front and side views till it is all lined up correctly.

    Hopefully you understand this tutorial, so to test you knoledge Im going to post up the level in the pictures above and get you to fix it.

    Attached Files Attached Files
    Last edited by Slay3r; 05-26-2003 at 10:31 PM.

  2. #2
    Join Date
    Oct 2002
    Posts
    110
    So you're saying that messy BSP has BSP-holes as result?

  3. #3
    Join Date
    Jan 2003
    Location
    Brisbane Australia
    Posts
    1,525
    Not all the time, some times you can get away with it.
    It mostly happens when brushes intersec at funny angles.

  4. #4
    rivit Guest

    Talking ye

    good 1 dude sure help a few ppl that do stuped things like me
    was in vtm but slipt my mind with every thing im trying to learn and still make my ctf

  5. #5
    rivit Guest
    hy my son nice tut but how the hell did you fix that brush on my level ffs its getting on me
    any whay if you like to teast level out tell me and ill up load it for you

    Moderators Comment: Watch your language please.
    -SLAYER
    Last edited by SLAYER; 05-31-2003 at 03:02 AM.

  6. #6
    Join Date
    Jan 2003
    Location
    Brisbane Australia
    Posts
    1,525
    Yeah sure Ill take a look at it.

  7. #7
    Join Date
    Jan 2003
    Posts
    536
    bsp holes happen alot when using semi solids, or when you "go back and fix something" after youve laid down zone portals. they also happen alot when trying to make a few brushes co-planer. i just had a nasty battle with a bunch of bsp holes in my map. however, i won.

  8. #8
    Join Date
    Dec 2002
    Posts
    74
    My advice is never to work off the grid when using bsp. Only staticmeshes don't really have any strange effects when put off the grid.

    One of my findings about invisible collisions in my current map is that there are statich meshes with a too much complex collision model which causes some strange collision effect across your entire level. Check one of the beams in the abaddonhardware usx package it has a too complex collision hull and that sometimes causes a collision without making a bsp cut, strange stuff.

  9. #9
    Join Date
    Apr 2003
    Posts
    6
    I read somewhere that pnly geometric shapes cause BSP holes. Do static meshes do too? What about a static Mesh and a geometric shape.

  10. #10
    Join Date
    Jan 2003
    Posts
    536
    has anyone ever LOOKED at epics maps? there are easily 500 brushes in most of them, and some have even more. ive seen over 700 bsp brushes in some of them. and none have bsp holes. why is this?

    simple. they know what theyre doing. using bsp isnt the worst thing you can do, but like anything, it takes a deep understanding of what bsp is, how it works, and why we use it.

    bsp holes happen most when either brushes "break" because their surfaces lose their plane. meaning you vertex edit it, and one side of your cube isnt a plane, and it causes warps and bends, and eventually breaks. OR they happen when you get too many added and subtracted brushes that intersect each other. every time you do this, you "cut the bsp tree." basically, every brush you add makes nodes. nodes are both good and bad. they are formed by vertices of added and subtracted brushes, and the polygons that surround them. nodes are what the engine renders, the more you have the more it has to render. also, bsp is occluded (not rendered) based on nodes. so having too many nodes is bad, and having not enough is bad because when you walk into a new zone, you load huge chunks of bsp, and everything touching them, at once. this causes glitches and hitches in your performance, and its very distracting. so having more nodes can soften this effect, or having too many could amplify the effect.

    bsp holes happen when the engine builds the geometry and makes an error, and occludes something that it should. i dont think anyone really knows why it happens, or whats the cause, but it is an error. it happens most when you have lots of coplaner brushes, or sloppily vertex edited brushes.

    they say to stay on the grid, and this is good, but its not nessicary. the reason youre told to stay on the grid is because it makes sure that all of your surfaces line up properly. its the easiest way to avoid holes. but just because youre on the grid, does not mean you will never have holes.

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