Camera circle movement

OpenGL
1

Hey there.

I want to make the camera moving along a circular path around the zero point (0,0,0).
So to calculate the position for the camera I use cos(deg) for the x movement and sin(deg) for the z movement in order to move along the path.
To obtain the zero point centered on the screen I just calculate deg + 180.
When you change your position with deg = 10° you have to turn arround with 190° to obtain the zero point centered.
Since glRotate() does work with degrees I thought this might work.
To put this in a code I did :

static float deg = 0;
deg+=0.1;

if (deg > 360.0)
{
   deg = 360.0 - deg;
}

static float temp = 0;
temp = deg + 180.0;
if (temp >= 360.0) temp = 360.0 - temp;

glRotatef(m_Camera.m_Rotate.y , 0.0, 1.0, 0.0);
glTranslatef( cos(inRad(deg)), 0, sin(inRad(deg)) );

glutSolidSphere(2,80,80);

This kinda doesn’t work like I want to.
For example, when I move the camera with 45° degrees I have to rotate by 145° to maintain the zero point centered on the screen.
For 90° I have to turn by 180°

EDIT :

Ok, problem is I have to change

temp = deg + 180.0;

to this

temp = deg + 90.0;

But can someone explain why it’s not working or why it’s only working with +90 ?
How does OpenGL rotate ? Clockwise or Counter-clockwise ?

Thanks in advance

2

Using http://www.opengl.org/sdk/docs/man/xhtml/gluLookAt.xml might make it simpler. You would compute new eye position and then use gluLookAt() to look at (0, 0, 0) (input it as center).

You can see in http://www.opengl.org/sdk/docs/man/xhtml/glRotate.xml that “rotation follows the right-hand rule, so if the vector x y z points toward the user, the rotation will be counterclockwise”. Or, in the specification itself, http://www.opengl.org/registry/doc/glspec42.compatibility.20110822.pdf Section 2.12.1: “The computed matrix is a counter-clockwise rotation about the line through the origin with the specified axis when that axis is pointing up (i.e. the right-hand rule determines the sense of the rotation angle)”. See also Appendix B corollary 15.