"Inversely Textured" Sphere?

Started by Jedi_Mediator, June 16, 2008, 02:36:51 PM

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Jedi_Mediator

I'm looking to create a series of six images to build a skybox for a game level. I have a theory of how to do it, but I can't figure out how to make it work in TerraGen 2.

I've got lots of options for skysphere images on the CGTextures site, and I'm thinking that somehow I could map one of those skysphere textures onto a sphere in TerraGen 2, position the camera inside the sphere, and then render six frames that don't require any atmosphere, shadows or practically anything else. Basically this is just a conversion from skysphere to skybox "format."

My main trouble is that, at least by default, TerraGen 2 maps a texture onto the outside of a sphere instead of the inside. How would I get the sky texture "inversely mapped"--a.k.a., mapped onto the inside of the sphere?

moodflow

The "background" is an actual object thats simply an inversed sphere.  You can tell since the diameter is a negative value (and huge so it encompasses the scene).  At this point, I have no ideas on how you could apply this method to your project.

Another thing that may work (but I haven't tried yet) is to render an image with a FOV of 360 degrees. 

Or you could render 6 separate images with a 1x1 width to height ratio, and FOV of 90 degrees.  You'd have to turn the camera laterally 90 degrees for 4 images such as N, S, E, W, and 2 images of which would be "up" and "down".  Then assemble these images in a 3rd party app designed for sky boxes.

I hope this helps.


Quote from: Jedi_Mediator on June 16, 2008, 02:36:51 PM
I'm looking to create a series of six images to build a skybox for a game level. I have a theory of how to do it, but I can't figure out how to make it work in TerraGen 2.

I've got lots of options for skysphere images on the CGTextures site, and I'm thinking that somehow I could map one of those skysphere textures onto a sphere in TerraGen 2, position the camera inside the sphere, and then render six frames that don't require any atmosphere, shadows or practically anything else. Basically this is just a conversion from skysphere to skybox "format."

My main trouble is that, at least by default, TerraGen 2 maps a texture onto the outside of a sphere instead of the inside. How would I get the sky texture "inversely mapped"--a.k.a., mapped onto the inside of the sphere?
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Jedi_Mediator

Quote from: moodflow on June 16, 2008, 03:58:14 PM
Or you could render 6 separate images with a 1x1 width to height ratio, and FOV of 90 degrees.  You'd have to turn the camera laterally 90 degrees for 4 images such as N, S, E, W, and 2 images of which would be "up" and "down".  Then assemble these images in a 3rd party app designed for sky boxes.

Heh. This is exactly the method I am using for making skyboxes, and practically the only one. The big problem is that I don't know how to map an image to the background, since normally the background encompasses atmosphere and rendered things like that.

Hmm. Maybe if I give my sphere a negative diameter it would go inverse?

Oshyan

I'm not entirely clear on what you want to do here - what value is TG2 in what you're aiming for? What TG2 elements are there in your scene and do they need to be affected by atmosphere? You could always just apply your texture to the background node and then turn off atmosphere rendering...

- Oshyan

iisthphir

Hello,
First of all why skybox?
skydomes are generally much nicer, i suppose they give you problems in some game engines though.
Anyway if you want a box you can make a nice one generated in terragen using the six camera technique (already tutorials on that), (I do wish they would add option for rendering panoramas in box, fish eye and lat/long though, and hdr)
If you must convert a skydome into a box though then use hdr shop very small download free and very easy to use, all the options you need to convert between many panorama formats with hdr support and dds and exr export.