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TheSteve

OpenGL Camera Class Woes and Questions

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I'm not sure if this post belongs here or in the OpenGL section, but here it goes anyhow. I'm currently trying to design a Camera Class from the ground up that would be able to look around the scene a-la a Quake-esk style view. From what I've read, I believe that I'm going to have to use Quaternations and don't really find the math to be especially challenging. That said, I do have some fundamental hang-ups when it comes to getting necessary view positions and vectors. Consider this article: http://www.gamedev.net/reference/programming/features/quatcam/ The concept is heavily reliant upon getting a view vector. Unfortunately, I don't really understand how you can "get" a view vector. If I'm not mistaken, it's the current position of your perspective matrix? Is that right? Moreover, it's also reliant upon using glulookat, which I don't believe is the hard core way to do it. Could someone fundamentally explain/verify: 1) What method you'd use to look around like you would in quake/doom 3/fear/etc? 2) How you establish "where" you are looking from? 3) How to actually get OpenGL to render from that location (glulookat?) 4) Where I can find some good resources on the method? I'm sure there are more questions that I left out, but I'm sure they'll come to me as the thread gets going. If I can get your help in this I'd like to make a very good tutorial on the whole subject.

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I hate to sound repetitive but, IMHO, quaternions are widely misunderstood. And then there are those who misunderstand the ways in which they are misunderstood! (But I won't get into that here :) Basically, you don't need quaternions for a simple FPS camera, and you might even be better off without them.

I'm going to repeat myself again, because it'll be much easier (and perhaps more effective) than writing a lengthy explanation of the concepts you asked about. A while ago I wrote a tutorial class that you can find in this thread. The class implements FPS character, FPS spectator, and 6DOF motion for both cameras and objects in OpenGL. (And not a quaternion in sight!) The only thing you need to supply is a vector class with basic functionality. The only gotcha is that the FPS modes assume a particular up axis (Y, IIRC), so you might have to make some adjustments for, say, Z up (which is common in FPSs). Anyway, maybe it'll be helpful to you, and I'll be happy to answer any questions you might have about the code.

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Jyk, you continually amaze me with how much butt you kick. Thanks man!
Heh, well I don't know about the first part, but in any case you're welcome! :) I do think that particular class is useful, though. I use it all the time in my demo code for both cameras and objects and have never had a problem with it. Anyway, I hope it helps, and let me know if you have any questions.

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