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# modding details

Discussion in 'rFactor' started by rlativo, Apr 1, 2010.

1. ### rlativo

I am currently preparing a mod for my GP2 team in order to explore Rfactor posibilities for driver´s training.

When building the .pm file I have realised that the origin for the coordinates in this file are not very well explained.. I mean that the official ISI modding guide tells that the (0,0,0) point is located on ½ of the wheelbase at chassis bottom tub height. However, after analysis of several mods previously done for GP2 I have seen that in those cases, the (0,0,0) point is not located at ½ wheelbase. In fact an example of Z coordinate (in Rfactor axis system, not in a SAE-type one) for the front spindles is -1,65m and 1,35m for the rear ones. So the (0,0,0) point clearly is not placed at mid wheelbase!

Where should I place the origin (0,0,0) for coordinates in the .pm file in order to build a good car model? Or does this have no influence at all?
On the other hand I would like to know also what is the meaning for the values in brakets in the following mod´s .pm file:
[JOINT&HINGE]
posbody=rl_wheel negbody=rl_spindle pos=rl_wheel axis=(-1.0,0.0,0.0)
Are they the (X,Y,Z) coordinates of this corner joint?

2. ### Ryan Callan

The 3D model of the car has a coordinate system that defines (0,0,0)

Additionally each 3d model of the wheels has a coordinate relative to this coordinate.

Lets say that the .pm file gives a rear wheel position like this:
// Rear wheels (includes half of rear-axle)
[BODY]
name=rl_wheel mass=(20.139) inertia=(0.927,0.659,0.659)
pos=(0.7,0.0,0.924) ori=(0.0,0.0,0.0)

If this position (0.7,0.0,0.924) does not coincide with the coordinate given in the 3d model of the wheel, then rfactor will shift the coordinates of wheel/upright/wishbones in the .pm file to coincide with the 3d model.

This means that the absolute coordinate of the .pm file does not have to be accurate, but the relative position of wheel/upright/wishbones for each corner is very important!!

A little tricky to get used to But once you got the .pm file done, you can move it around simply by moving the 3D model