i need to rotate a vector according to the mouse movement: i use this vector as a direction vector for the movement and later for things like shooting (rockets etc.). if i move the mouse to the left or right, the vector rotates around the y-axis and if i move the mouse up or down the vector rotates around the x-axis. for this i have two variables xrotation and yrotation. i add the x and y movements from the mouse to that variables. every frame i reset the vector to: x = 0 y = 0 z =-1 and then i rotate it by xrotation around the x-axis and yrotation around the y-axis. this works already, but if i rotate the vector +90 degrees around the y-axis so that it is x = 1 y = 0 z = 0 and then move the mouse up and down, it has no effect on the y coordinate of the vector. i know why, because i now have to rotate the vector around the z-axis to point up and down. but i want to rotate the vector around the x-axis every time to point up and down without looking on the y-rotation. also if i rotate the vector 180 degrees around the y-axis and then point up and down the vector moves the inversed way (if i move the mouse up the y coordinate decreases and if i move the mouse down it increases). i heard about gimbal lock and that i can solve it with quaternions. is my problem gimbal lock or can anybody help me ?