OpenGL - Unwanted z axis camera rotation

Question

When I rotate my camera on the X axis while the Y rotation is > or < than 0, it also rotates the Z axis.
Why does it do this?

if(Keyboard.isKeyDown(Keyboard.KEY_UP)){
    xRot-=speed_rotation;
    glRotatef(-speed_rotation, 1, 0, 0);
}
if(Keyboard.isKeyDown(Keyboard.KEY_DOWN)){
    xRot+=speed_rotation;
    glRotatef(speed_rotation, 1, 0, 0);
}
if(Keyboard.isKeyDown(Keyboard.KEY_LEFT)){
    yRot-=speed_rotation;
    glRotatef(-speed_rotation, 0, 1, 0);
}

if(Keyboard.isKeyDown(Keyboard.KEY_RIGHT)){
    yRot+=speed_rotation;
    glRotatef(speed_rotation, 0, 1, 0);
}

I think I know what is causing it, but I'm not so sure...

Answer 1

不要glRotate()在键盘的处理程序，只需更新X / Y旋转值就像你正在做的，并发出一组的glRotate()s在绘制之前。