Arcball with OpenGL

[System123]

Hi

I am trying to implement an arcball view of a heightmap I created using OpenGL and Qt4 in c++. I have looked at various sites, with example projects but I can't make sense of it. Why do they use quaternions? Is this necessary? I don't quite know how the whole glRotate call should look, because some sites say I must perform the operation on the Model matrix and others say the projection matrix. Can someone please give me a good explanation or link.

Thanks

[stampede]

Here: http://nehe.gamedev.net/
You will know answer to all your questions and a lot more. Just try to learn OpenGL and graphics programming step by step. Dont copy-paste the code and be happy it works, its useless. Also, you must be familiar with linear algebra, without it graphics programming will be really painful (if not impossible).

Why do they use quaternions?

Because using quaternions is efective way to represent and calculate rotations in 3D.

Is this necessary?

No. You can use matrices.

Oh, almost forgot: http://www.opengl.org/sdk/docs/man/

[System123]

Hi

thanks for the links, I am new to graphics programming, and do not have time to start with basic examples as I have a project to do for varsity, which gives me 3 weeks for quite an advanced graphics program. I have a good knowledge of linear algebra, (part of my course). I believe that NeHe has the answers I need.

Many Thanks