[gameprogrammer] Re: Rotation, Rotation, Rotation...

  • From: Vince <uberneen@xxxxxxxxx>
  • To: gameprogrammer@xxxxxxxxxxxxx
  • Date: Mon, 17 Mar 2008 05:30:21 -0700 (PDT)

It sounds like you're trying to overcome Gimbal lock. 
I ran into the same problem with my own camera but I
haven't gotten around to fixing it yet.
It looks like the definitive solution is quaternion
rotation.
http://www.gamedev.net/reference/programming/features/quatcam/

Vince~

--- richard sabbarton <richard.sabbarton@xxxxxxxxx>
wrote:

> Hi Guys,
> 
> I have a problem and I am absolutely sure that I
> have missed something
> obscenely obvious.  This is C++ with OpenGL/SDL.
> 
> In a 3D environment my player struct has 3 values
> for rotation around
> x,y and z.  I want the player to be able to freely
> rotate around all 3
> axis and I always want the mouse/joystick/keypad to
> operate the x and
> y axis rotation.  When I initially move the mouse
> the rotation is
> correct.  Left/Right and my scene rotates left and
> right.
> 
> If I rotate around z and then move the mouse my
> scene moves up and
> down instead of left and right.  Now, I thought that
> all I needed to
> do was change the order in which I rotated around
> each axis.  I
> thought that if I rotated around Z first and then x
> and y after then
> the movement of the mouse would always appear
> correct onscreen.  This
> is what I call:
> 
> glRotatef(Player.ZRot,0.0f,0.0f,1.0f);  // Rotation
> around Z axis
> glRotatef(Player.YRot,1.0f,0.0f,0.0f); // YRot is up
> and down around X axis
> glRotatef(Player.XRot,0.0f,1.0f,0.0f); // XRot is
> left and right around Y axis
> 
> 
> I thought that after performing the rotation the
> subsequent rotations
> would be relative to the previous one.  So, if I
> rotate 90deg around Z
> I thought it would then rotate relative to that
> effectivly switching
> the x and y axis.  But it doesn't does it...
> 
> So I guess that is my question...  How do I perform
> a rotation and
> then make all subsequent rotations relative to that
> initial rotation?
> 
> Regards
> 
> Richard
> 
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