Rendering polygon

[rev111]

After doing a step, I am trying to send the vertices of a polygon body to a client and render them there. Its a simple convex polygon falling on a plane. The body is rendered and I can see it falling after a few steps, but it's not rotating. Even if I set an angle of 0.8 when creating the body, it is still rendered as if angle=0.
It seems that neither body.concavePath nor body.shapes[0].vertices are ever changing. However, body.angle is changing!
Am I looking at the wrong place in body? Or do I have to apply the angle to the vertices myself?
I tried to check how it is done in the demos and the rendering sandbox, but the rendering code there is too opaque for me.
Where should I read the vertices of a convex (and concave) polygon?
Thanks for any help!

[rev111]

I should have examined the examples. The box example shows how it's done with ie Pixi:

// Transfer positions of the physics objects to Pixi.js
graphics.position.x = boxBody.position[0]
graphics.position.y = boxBody.position[1]
graphics.rotation = boxBody.angle

So I have to send the angle to the client-side renderer as well, the polygon vertices appear to have an initial position with angle=0 and never change. The client renders this initial polygon and rotates it afterwards.
That makes me wonder: In order to calculate collisions and impacts, p2 needs to do a new rotation calculation for each body on each step, no? Then it seems to calculate a new angle and writes this new angle in the body, but not the vertices.
Isn't that quite inefficient? This is an honest question, I don't know much about physics engines and it may very well be the right way to do that...