Yesterday dandan reported a bug for OTTD (http://bugs.openttd.org/task/2444). Thanks dandan, also for the test grf
. Planes use property 7 resp. callback 12 of train 0 for mail when gradual loading. As we were unsure about the correct behaviour, we choosed the easy way, and tested it in TTDP r2072. Unfortunatelly that resulted in the same bug
So that did not help, and we are still unsure about the correct behaviour. Options that came to mind include:
a) Use the same load amount for mail as for passengers. However, as mail capacities are usually a lot smaller than passenger capacities, mail is basically loaded immediatelly, and then has to wait for the slow passengers to join them. OTOH the old (but wrong) train load amount looked nice in game.
b) Base the mail load amount on the passenger load amount using a fixed factor, or using the quotient of passenger and mail capacities (if they are not zero).
c) Call callback 12 for the main plane (carrying the passengers) and the shadow of the plane (technically carrying the mail
[0]) The callback can then use variable 40 or better 47 to decide which cargo is meant. However this might be unexpected to existing grfs, and variables accessed through varaction2 type 81/85/89 might not contain valid values. Type 82/86/8A should work though.When the callback is not used, one has still to decide between a) and b).
So the main question is now: Which solution do TTDP devs prefer, and which behaviour is expected by grfauthors of existing and future (
) planesets?[0] Compare the shadow of a plane with a wagon attached to a train.