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Sky Plane - Where to start?

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Lets see I've tried SkyCube and thought it looked pathetic. I tried SkyDome and felt as tho it worked, used it for a game, still didn't feel comfortable with it. I have seen several screen shots and played several new games which use sky plane. It looks beautiful with apparently minimal effort. With extensive effort a sky-plane will look almost realistic. Now, I cannot find any articles, tutorials, or good threads. If someone could give me a lamen explanation or post an article, tutorial, thread I'd be quite pleased. Thanks, Halsafar

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You need some way to 'enclose' the terrain with sky since the sky comes down to the ground at the horizon. Sky-boxes can look fine and sky-domes practically perfect so it's probably your textures or how you fit them to the polygons which causes problems - do you have any screenshots of your attempts with these?

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I refuse to use Skybox, I've seen them done very well and they definetly do not suite an open terrain fantasy-like work.

Here is a shot of my sky dome.
I did not like how it looked, yes the texture looks function at the point I took the screeny, thats why so you could maybe assist that. The rest of the texture looks great. This screeny is from a debug form of an old game I made in Dx7, the camera is below the terrain so its culled and you got a good look at the sky.

If you have played World Of Warcraft or Final Fantasy XI, they do not use SkySphere and they have some of the best looking sky's I've seen.

So regardless of how you wish to address this, I want to get a sky plane working because SkySphere just doesn't suite my needs.


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It's definitly your UV or mesh that's messed up, not sky domes in general. I would double check that you have set everything up correctly.

As for sky planes, I believe they are ussually used in conjunture with skydomes/boxes. You let the sky dome cover everything, and then use the plane to add a layered look to the sky. The end result is really spectacular, especially if u animate the uv's of the plane, so it looks like the clouds are moving and stuff.

As for actual resources, I don't have any off hand. I know there's some info in a book I have. I'll take a look when I get a chance and let you know.

Matt Hughson

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Quote:
Original post by _DarkWIng_
Skydome can look very nice with a few tricks: pic1, pic2 (and yes, the clouds are moving/scrolling). It's all how you generate your texturing coordinates.


I wish you'd release your darn source for the atlantis demo :-) I am sooo much wanting to learn from that!

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Dark Wing, beautiful sky, I love it.

Care to share the tecniques used?
Was it a sky dome and a sky plane?
It has to be, I can clearly see the dome and the cloud plane...




My tU and tV coords where a little funky, I have no idea how to fix it.
Anyone care to post there dome drawing/texturing routine?

Edit:
How did you get skydome to look big enough to capture the terrain without seeing the dome chop through the terrain... I've had that problem before, as you walked towards the dome you'd see it in some places clearly cutting through the ground. The only way to fix it was to raise the dome and then it would no longer meet the terrain and the horizon would look funny.....

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Quote:
Original post by Halsafar
Care to share the tecniques used?
Was it a sky dome and a sky plane?
It has to be, I can clearly see the dome and the cloud plane...

It's just a sky-dome (no planes), that's the point. You can try the demo and see the wire-frame.
Texturing is done by projecting texture coordinates from virtual sky-plane to real skydome. A simple steps:

-Create sky-dome with some radius R. For better results make it anisotropic(sp?) tessellated so it has more triangles on horizon.
-Create a virtual plane (at height H) that will represent your cloud layer.
-For each vertex V of sky-dome create ray R from origin to vertex.
-Find the point P=(x,H,z) where R goes trough your plane.
-Use point P (x,z components) as texture coordinates for vertex V
-Use distance from origin to point P as weigh for alpha blending so your clouds fade out at horizon.
-Be careful with rays that are parallel to plane.


edit: One this important here is choosing parameters R, H and distance weighting function. Here the only solution would be trial and error. Find something that looks good for you.

Quote:
Original post by Halsafar
How did you get skydome to look big enough to capture the terrain without seeing the dome chop through the terrain... I've had that problem before, as you walked towards the dome you'd see it in some places clearly cutting through the ground. The only way to fix it was to raise the dome and then it would no longer meet the terrain and the horizon would look funny.....

-Standard way: Render sky-dome first with z buffer disabled. Most games use this.
-I added a little trick to it (idea from Charles Bloom's page). I fade terrain with distance so it 'melts' into the sky showing no borders. It has some other nice side-effects but also some problems. It's up to you to decide if it's worth it.

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Okay I've done nothing with RAYS, but is it simple a vector position, vector direction and length to travel?

Like a bullet from a gun to its target...


What do you mean by weight? (lol don't take me wrong I know my body weight is 140lbs, but what do u refer too in this content?)

Now, your method there is very intillegent I can see how you got such a nice looking skydome. Although I do believe a cloud plane might be necessary to simulate some realistic looking clouds but thats beside the point.


I'll see if I can get it working but it seems a bit tricky.
Do you happen to have any tutorials? articles? books I should buy/read? that would cover this topic in a professional area than a thread...


Thanks,
Halsafar

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