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thallish

Cube Map Resolution and Skybox Questions

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thallish    202
Hi In Real-Time Rendering they propose 'ScreenResolution/tan(fov/2)' is the approximate texture resolution, so if I have a Field of View of 45 degrees, and the screen resolution are '1024*768', then the appropriate texture resolution would be (1024*768)/(tan(45/2)), right? Then if I wanted a square textures then I would just take the square root of the texture resolution and then I get 1378*1378. But isn't that very large or is it expected to be that large? I mean thats a lot of memory when you have to account for 5 or 6 faces. I also have some questions on when it is more appropriate to use a sky sphere/sky dome instead of a sky box. My main concern is what can't be done with a sky box, but with a sky sphere/sky dome? Most people don't really expand on the issue but just state that it all depends on what you need to do, and a for static sky a sky box is most commonly used. But what are some of the issues that arise? I imagine that having a full day-night cycle would be hard to do with a sky-box because of the movement of skies and celestial bodies, but I can't really explain it, it is just a gut feeling. I have also been searching GD and have found some answers that I have to get clarified, but a more thorough explanation of the subject would be very helpful: 1) _Darkwing_ writes in this thread: Sometimes domes can be used for low-frequency base color or to use some specific mapping effects that can't be made so simple with sky box. Questions: What is meant by low-frequency base color? What mapping effects can not be made with a sky box? 2) I once found a thread where Yann L. said something about atmospheric gradients and to properly depict them, a sky sphere/ sky dome would be needed. Can't find it now unfortunately. Questions: What are atmospheric gradients? color changes? How would one go about showing them? So if anybody can help me get wiser on the subject please do![wink] Regards

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