Well, I've tried to get a skybox up and running and when I load up my level, the sky just displays a lot of HOM and stuff. How exactly do I set a skybox up?

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I've been seeing the term skybox being thrown around lately. what exactly is a skybox? what are they used for?

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A skybox is basically an attempt to make the sky as realistic as possible. In Doom all the way to Quake, the sky is essentially a big, flat surface which uses the same texture all around.

Heretic 2 was the first time that I saw a skybox, but I really didn't pay much attention to it at the time. A skybox is like a large cube, with each side containing a section of the sky (and the ground when looking straight down). It's sort of like a Doom map using a sky with a size of 1024, except with a unique top and bottom section included.

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Fredrik said:

Why not simply play the example level to find out? :)


the reason why I asked is cuz I didn't get the point from playing the example. btw, thanks for the explanation ichor. I'm gonna try it out and if I can do it myself.

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You can get HOM style effects from a skybox if you don't pay too much attention to where you place the skybox camera, and if you have certain effects in your level.

eg, if you have created a level where the edges of outside areas are surrounded by low walls (effectively lowering the edges of the sky) or you have high platforms that let you look down towards some areas using F_Sky, then you may get a HOM type effect if your camera is sitting on the ground in the sky box.

Remember, the sky is drawn from the viewpoint of the camera. If the player is in such a position as he can look down towards a sky area, the camera view is essentially looking down into the floor (at least thats how it seems).

Give your skybox camera a zcoordinate to lift it slightly and see if that helps.

Once you get the hang of sky boxes, you can do all sorts of fancy things with them, including multiple skies in the same level, animated skies, varying the appearance and brightness of the sky, scrolling clouds over fixed mountains or buildings, fake teleport portals that let you see your destination, and to my mind one the cleverest, Gooberman's starbox example showed the illusion of being in a flying space craft that flies into the superstructure of a space station using a moving camera.

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Dadealus: Alien Defense is making alot of use of sky boxes and it looks very cool.


Cadman - Member TeamTNT

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Ichor said:

Heretic 2 was the first time that I saw a skybox

IIRC Heretic 2 used the same skybox code that came with the Q2 engine. Surely you played Q2 before Heretic 2 :P
ZDoom's skyboxes are similar to the ones used in Unreal-engined games (and what I'll be using in my own engine) - a section of the level is set aside to be used as the sky viewed from a specified point. The great thing about this is that you can specify the point to be wherever, even inside the map itself (one person on the ZDoom forums was inspired by my starbox example to use skyboxes to make teleporters where you could see the destination).

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I don't have Quake 2 and I haven't played the demo for more than a few minutes.

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I got the sky box going with SKY2 background, but the F_SKY ceiling isn't scrolling. do I have to use something else that isn't in the doom2 iwad?

I made the litte triangle sector, but I'm curious as to what the function of that is.

::edit:: I put a cyberdemon in the skybox. its huge looking. now if I could get a gojira sprite and have him walking around in the city that would look awesome. ::end of edit::

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Enjay said:

You can get HOM style effects from a skybox if you don't pay too much attention to where you place the skybox camera, and if you have certain effects in your level.

eg, if you have created a level where the edges of outside areas are surrounded by low walls (effectively lowering the edges of the sky) or you have high platforms that let you look down towards some areas using F_Sky, then you may get a HOM type effect if your camera is sitting on the ground in the sky box.

Remember, the sky is drawn from the viewpoint of the camera. If the player is in such a position as he can look down towards a sky area, the camera view is essentially looking down into the floor (at least thats how it seems).

Give your skybox camera a zcoordinate to lift it slightly and see if that helps.

Once you get the hang of sky boxes, you can do all sorts of fancy things with them, including multiple skies in the same level, animated skies, varying the appearance and brightness of the sky, scrolling clouds over fixed mountains or buildings, fake teleport portals that let you see your destination, and to my mind one the cleverest, Gooberman's starbox example showed the illusion of being in a flying space craft that flies into the superstructure of a space station using a moving camera.


I'm willing to bet that having a self-referencing skybox would cause HOM as well (has anyone checked?).

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GooberMan said:

IIRC Heretic 2 used the same skybox code that came with the Q2 engine. Surely you played Q2 before Heretic 2 :P
ZDoom's skyboxes are similar to the ones used in Unreal-engined games (and what I'll be using in my own engine) - a section of the level is set aside to be used as the sky viewed from a specified point. The great thing about this is that you can specify the point to be wherever, even inside the map itself (one person on the ZDoom forums was inspired by my starbox example to use skyboxes to make teleporters where you could see the destination).


Wow. I never knew that ZDoom has this.

Does JDoom have a similiar system or does it have something else?

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KDarigal said:

I'm willing to bet that having a self-referencing skybox would cause HOM as well (has anyone checked?).

Whipped up a map in a minute to test it, the skybox draws normally using MAPINFO's sky definitions (or default sky for whatever map you're on)

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