I've found something that can be interesting. glRotated(angle, x, y, z) is performing the rotation angle around the vector (x,y,z). That's why glRotated(90, .5, 0, 0) did not rotate the ball at 45 degrees.

I guess I need to do some math to calculate the rotation that is the sum of the rotation on each axis. Then I would have the angle of the rotation and the vector of the rotation, and would just have to call glRotate accordingly.

So, is there any way to do that (I have a vector class with dot and cross product, calcul of an angle between 2 vectors).

[edited by - Roming22 on November 12, 2003 3:11:15 PM]

I am talking to myself ?

I don''t care, I''ve found the solution.

First I needed a matrix in my class:

double rotationMatrix[16];

Then I needed to initialize it as the Identity (once, at the very beginning of the game):

glPushMatrix();
glLoadIdentity();
glGetDoubled(GL_MODELVIEW__MATRIX, rotationMatrix);
glPopMatrix();

Afterwards, each time the ball rotates of an angle alphe around the axis (x,y,z) I have to do the following:

glPushMatrix();
glLoadIdentity();
glRotated(alpha, x, y, z)
glMultMatrixd(rotationMatrix);
glGetDoubled(GL_MODELVIEW__MATRIX, rotationMatrix);
glPopMatrix();

Finally when drawing the ball I do:

glPushMatrix();
glTranslate(position.x, position.y, position.z);
glMultMatrixd(rotationMatrix);
gluSphere(quadric,radius,sections*2,sections);
glPopMatrix();

And that makes my ball(s) roll and pivot the way it should.
I could find it out thanks to the code of BilliardGL. It wasn''t easy to figure everything out as the code is in german, and I don''t speak a word of it, which made it difficult to find the right classes and functions (and for your information, a ball is a "kugel" in german).

Yep, I won''t touch it.

I guess the OpenGL calls are very fast and therefore I think that adding a quaternion class or doing my own matrix multiplication will result in a performance decrease.

But that''s my guess...

d stands for double.
You have to use degrees in glRotate functions.
The conversion from radians to degrees is simple:
radians = degrees*PI/180

Hope I helped,

Roming