Horde3D

Next-Generation Graphics Engine
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 Post subject: Skybox texture tutorial?
PostPosted: 25.01.2009, 19:24 
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Joined: 21.12.2008, 23:46
Posts: 23
What I am really missing in the tutorials section are some hints on how to
create a custom texture for the skybox.
Unfortunately the most common skybox-texture format is
Code:
          TOP
   LEFT  FRONT RIGHT BACK
        BOTTOM

instead of the Horde format
Code:
          TOP
   LEFT  FRONT RIGHT
         BOTTOM
         BACK

Of course I can convert the common format to fit into Horde's pattern
and move the BACK-side "under" the BOTTOM and rotate it by 180°
but it somehow corrupts the distortion that makes the vertical sides
fit to the top and bottom sides when mapped onto the cube and it
always looks crappy. Creating my own one from scratch wasn't successful
due to problems with the distortion.
Are there any tutorials on how to make Horde-compliant skybox textures?
Or are there any available for free? A space-skybox would be great. ;)


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PostPosted: 26.01.2009, 00:32 
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Joined: 19.03.2008, 01:22
Posts: 79
You could easily modify horde to work with your skybox arrangement of choice :)


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PostPosted: 26.01.2009, 09:45 
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Joined: 11.06.2008, 10:34
Posts: 119
Ive not tried it, but perhaps a tool worth looking into is the ATI Cubemap maker. I think the current default direction does need moving to a more standard layout? :)

As for the skys themselves you may find it better to create a geo cube, and map the 6 texture accordingly not using the Skycube shader - at the moment theirs allot of pixel wastage.

Ive tried shunting in some very large images via the skybox, but almost impossible to get the quality without bogging down the system.

wakko wrote:
Or are there any available for free? A space-skybox would be great. ;)


If you want a space scene (starfield), I can make one up for you sometime.

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PostPosted: 26.01.2009, 15:35 
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Joined: 05.03.2007, 19:38
Posts: 167
Location: Romania
I'd recommend using a sky dome. Less stretching that way. Been using them for a while now.

I switched to them when i've encountered the same problem as you have and was looking for a fix.

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PostPosted: 26.01.2009, 22:43 
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Joined: 10.09.2006, 15:52
Posts: 1217
The cubemap layout that we have now is called vertical cross. We had the other layout (horizontal cross) before but more tools (like HDR Shop) seem to support the vertical cross, that's why it was changed. Actually there should not be any distortion when manually converting the cube layout from horizontal to vertical. I did that with the sample sky cube map and noticed no problems.

When we get dds support, dds will probably be the format of choice. ATI's CubeMapGen can be used to generate the dds from a vertical cross.


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PostPosted: 30.01.2009, 12:27 
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Joined: 21.12.2008, 23:46
Posts: 23
HDRShop was a great hint. Didn't know about that. Thanks


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PostPosted: 07.01.2010, 07:59 
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Joined: 09.09.2009, 18:58
Posts: 107
How would one go about implementing a 3D skybox such as those seen in Valves Source engine?


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PostPosted: 07.01.2010, 16:14 
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Joined: 15.06.2008, 11:21
Posts: 166
Location: Germany
afaik that's just a second scene with much smaller scale (you can see it e.g. in counterstrike when you fly away from the map, tiny geometry of a less detailed map floating around there with the center missing where the real map is inserted). Should be quite simple when done with Horde3D).


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PostPosted: 07.01.2010, 18:46 
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Joined: 09.09.2009, 18:58
Posts: 107
Yeah, I'm aware as to how they are made in Hammer, but what I am puzzled about is how they make the 360 degree camera and then render it out to the skybox utility texture.


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PostPosted: 07.01.2010, 20:27 
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Joined: 15.06.2008, 11:21
Posts: 166
Location: Germany
huh - is it even rendered to a texture? Why not just manually draw it as 3D geometry? The effect would be the same, but with less textures involved.

If you *really* want it on a texture (but this needs more rendering work actually as you cannot cull invisible geometry that quickly and have a much higher memory throughput), then you have to use 6 cameras, each for one cube side. I actually did something similar for point light sources somewhere in the community repo although I quite think that that branch is long dead (wasn't any good either).


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PostPosted: 08.01.2010, 00:04 
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Joined: 08.11.2006, 03:10
Posts: 384
Location: Australia
Yeah I'm pretty sure they place the camera inside the sky-box model and render the scene, then they clear the depth buffer, place the camera back inside the actual world model and render the scene again.


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PostPosted: 14.01.2010, 15:47 
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Joined: 09.09.2009, 18:58
Posts: 107
DarkAngel wrote:
Yeah I'm pretty sure they place the camera inside the sky-box model and render the scene, then they clear the depth buffer, place the camera back inside the actual world model and render the scene again.


Picture a skinny pale white guy being crushed by big block letters that spell out the word "DERP!" and you get the general idea of how I am feeling right now.


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