Regarding the New Physics Model v2.0

December 10, 2009, 03:19:43 pm

I have given a preliminary test of Bernd's new physics model v2.0 , and I notice the following things while testing with a train from pak64 :

(1) the train doesn't slow down at 45 degree curves
(2) the train doesn't slow down when climbing up a one-level high slope, though it will slow down if the slope is 2 or more levels high
(3) the train, with a max speed of 90km/h, occasionally goes up to 91km/h. Not happening all the time though.

For (1) and (2), are they intended?

Re: Regarding the New Physics Model v2.0

Reply #1 – December 10, 2009, 03:56:06 pm

Knightly,

(1) might be caused by the fact that the train's speed limit is lower than the track's speed limit. In Simutrans-Experimental, corners simply reduce the track's speed limit by a certain factor, so, if the train is going slowly enough to start with, it will not slow down further for corners (especially gentle corners). If the track speed limit was at or close to the train speed limit, however, there is indeed a problem. (If I recall correctly, I tested this a while ago and I think that it worked all right).

The others do, however, need looking into. Also, I have found that the acceleration is rather too fast with the model as currently implemented. Ideally, a convoy that takes a certain distance to accelerate in real life should take the same distance in Simutrans when the scale is taken into account. For example, suppose that, in real life, a certain train (particular locomotive and certain number of carriages) would not get to maximum speed for 5km, it should take 5 tiles to reach maximum speed at 1,000m/tile; 10 tiles at 500m/tile, and 20 tiles at 250m/tile. The scale should be factored into the acceleration but not, of course, the total amount that can be hauled at any given maximum speed.

Re: Regarding the New Physics Model v2.0

Reply #2 – December 12, 2009, 11:18:01 pm

(2) the train does not slow down just because there is a slope. If the engine is strong enough to compensate the additional load, is does not slow down. A convoy at the power limit on a plane way must slow down noticeably even on a one-level slope.

(3) I've adjusted the speed calculation to more accurately obeying the limit. A little overshooting can still happen, but in the end all convoys should drive at the limit. The overshooting can be observed in the acceleration graph. I suggest to watch airplanes on runways (e.g. pak64: Concorde).