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Coordinate systems in Racer.

INTRODUCTION

A car is built out of graphics & physics. It can be quite difficult to see how things are interrelated. The later Racer versions introduced the concept of a (virtual) nullpoint, around which the car is built.

THE NULLPOINT

The nullpoint is the center of modeling the car (not just graphically). Most things are specified relative to the nullpoint. In the past, the CG actually was the same as the nullpoint. So it makes sense to start out with a CG at (0,0,0) and try to keep it that way.

To find the height of your nullpoint, set (in the car's car.ini) car.cg.y to 0, then run Racer with the car sitting still on a perfectly flat track. Press Ctrl-9 to see the CG height; that is the height of your nullpoint as well then. You may want to record this value as a comment in your car.ini file.

THE CG

Try to start out with a CG of (0,0,0). It will simplify things. The CG is specified relative to the nullpoint.

(last updated June 29, 2009 )