# How do I convert Euler Orientations to 2D rotation.

Let me first describe what I am trying to accomplish...

I have a 3D simulated environment that describes the orientation of objects as Euler angles (alpha, beta, and gamma).

In this environment I have an object with an obvious forwards and backwards direction (lets say a coin with a forwards arrow drawn on it).

Now I want always know what the rotation of this coin is at all times relative to the world.

If the coin is simply rotating around its vertical axis I can measure this as the rotation to the world.

But if the coin was to flip over (now the arrow is on the bottom of it), I have not measured any rotation in the vertical axes, but the arrow is now pointing 180 degrees in the other direction.

I'm not sure if I am being tackling this the wrong way, but I cant seem to find a way of working out something heading from the given Euler Angles.

If anyone knows an easy way to convert between the two, that would be great.

C