The idea (for the interpolating case) is that drawing occurs between two physics states; say at time0 physics has state0 (position, orientation etc) and at time

The idea (for the interpolating case) is that drawing occurs between two physics states; say at time0 physics has state0 (position, orientation etc) and at time1 physics has state1. Then the state at draw time is an interpolation of the states (lerp for positions, slerp for orientation quaternions etc) with parameter t (where t is (draw_time - time0) / (time1 - time0)). The non-intuitive thing is that drawing is always bracketed by a physics step in the past and a physics step in the future.