re: [Algorithms] Skysphere or skybox?

[George W. <ge...@ap...>]

On Wed, 24 Apr 2002 11:50:33 +0200, "Joris Mans" <jor...@pa...>
wrote:
> Since I don't know much about it , I'll try to get some info here. Can
> someone explain me the advantages and disadvantages between using a
> skybox and a skysphere? More specifically, I would like to show a
> horizon with e.g. mountains on.

I'd throw in a third option: sky cylinder. The horizon wraps around like a
cylinder with the ground cutting off the bottom and a sky plane (w/wo
clouds) cutting off the top.

BTW: When we were playing with the skybox code we were seeing some
deformation of the flat textures near the edges of the box (where the faces
meet) when we rotated the box around our camera (esp. When the edge was
directly ahead of the camera). For some reason there was much less of this
distortion when we keep the box vertices constant (in relation to the
camera) and only changed the texture coordinates at those vertices in order
to rotate the image. We then switch to the cylinder and the distortion
completely vanished. This also allowed us to use a display list preceded by
a glRotate to spin it. This was much faster than the box or remapping the
texture coordinates.
--
Enjoy,
George Warner,
Mixed Mode Magic Fragment Scientist
Apple Developer Technical Support (DTS)