In all these years no proper rear view mirror thing has been implemented, mostly probably because it's impossible in some way, either camera-related, rendering-related or something else.
What if a very basic wireframe, or even a box, using coordinates of a vehicles' bones (and peds bones), are drawn? It wouldn't be pretty or detailed, but it'd give some valuable information for the player, especially when racing or evading the cops.
So how I envision this happening is:
- Get the points on entities behind the camera/vehicle
- Translate those points to whatever is in the camera's view (get relative coords to the camera and flip them all?)
- Scale the points to some miniscule size and translate them again, inside the car/in camera view
- Rear view mirror achieved?
I'm not sure if some basic translation and scaling would work for this. There's also the thing about perspective. I don't think one can do anything other than a simple isometric projection with this method. Math is also an issue probably regarding scaling/fov/camera stuff where some matrices are used? idk
I'm giving it a shot somewhen, probably.