amphetaman@[EMAIL PROTECTED]
wrote:
> Greetings! I recently started learning OpenGL and I have run into
> quite a problem. I really have no idea how to implement a simple
> camera using OpenGL's transformation functions. What particularly
> bothers me is the order in which transformations must be applied.
>
> Suppose the camera is located at (x, y, z) and its rotation is -45
> degrees (from the default orientation, that is, looking towards (0, 0,
> -1)).
>
> If I translate first, by calling glTranslate(-x, -y, -z), the rotation
> will have that point as its origin. I don't need that.
>
> If I rotate first, I will have to somehow calculate the translation
> vector (because forward, for example, won't be (0, 0, -1) anymore).
>
> Any help is appreciated.
If you can think in terms of transformation matrices and their
compositions, then Section 5.6 of:
http://www.jgcampbell.com/graphics1/cgogl.pdf
may shed some more light (fungus has given you a good answer).
Or, maybe better, find an online version of the Red Book --- the old 1.1
version will do fine.
If you mooch around my course website (e.g. ch05.zip), you'll find the
model1.c program and any function library that it uses. However I should
add that my lecture on this topic contains vigorous arm waving and
supplementary use of a whiteboard.
You should also have a look at gluLookAt (sp.?) and how positioning and
orienting the camera, and glTranslate and glRotate.
Best regards,
Jon C.
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