How should I get the relative facing direction of camera?

[1FoNo1]

Hi! I am working on this tank movement that allows player move forward by pressing W key when camera is looking at the forward of the tank. The player can move backward also by pressing W when camera is looking at the back of the tank. I need to find a condition to set the forward vector to negative. But I am struggling to find that condition, the condition by checking camera forward vector will be affected by tank’s own rotation… Please help me out!

[Chatouille]

Use DOT product between camera forward vector and tank rotation forward vector, if result is negative then you want to go backwards.

Something like this

[1FoNo1]

Thank you! That works for me!