[Torcs-users] Help with variable radius in curves

[Simone S. <sim...@gm...>]

Hi everyone!

I'm trying to understand how variable radius curves are implemented in
TORCS. I'm following this file [1]. In my Main Track, I have

<attnum name="profil steps length" unit="m" val="4.0" />
<attstr name="profil" in="linear,spline" val="linear" />

This means that I should not enter the spline branch of the if at line 978,
but the else branch, which sets "steps" at 1. However, this should also
mean that my curve segments have a single step, with the start radius, and
no connection to the end radius. The "radius" variable is in fact changed
and set to the value of end radius at the end of the while loop (line
1280), but then the while exits right away because the number of steps has
been reached.

However, both in the track editor and in the game, the curve segments are
rendered the same way, i.e., with variable radius. The track editor clearly
shows a number of "subsegments", each with (apparently) a different radius.
However, I can't understand how the number of subsegments is determined, as
they don't match either the number of steps calculated in track.cpp (which
should be 1) nor the ratio between the length of the segments and the
profil steps length.

Can anyone please shed some light on this?

Thank you!

Regards,
Simone

[1]
https://sourceforge.net/p/torcs/code/ci/master/tree/torcs/torcs/src/modules/track/track4.cpp