Free ship!

[Cmdr James]

In an unmodified trunk, with a handful of oxps, I sometimes get a zero cost ship for sale in the shipyard. If I buy it, then it has its normal resale value, so I could make a stack of money this way. It is very hard to test, as I do not know what conditions cause it to occur, and removing oxps removes most of the ships I have seen it on.

In my most recent case (save-file available) it is a mosquito trader available for free. It is a "standard customer model, forward weapon upgraded to mining laser" There is another mosquito for a normal price (212300) at the same shipyard.

Is anyone looking at the (many) different ways ship value is calculated? If no one is, then I might try to get a single method on ShipEntity called something like calculateCost and see where I get to.

Just an idea, the standard forward weapon is a beam laser, which is 1000, and it is "upgraded" to a minig laser (800) it doesnt seem likely, but maybe this downgrade is breaking the calculation someplace?

[JensAyton]

That saved game would certainly be useful.

[Influence D]

I've also seen this, but I didn't think to keep the save file (because I thought the shipyard reset every time I loaded?)



I haven't updated my SVN build for about a week, maybe... I have a few OXPs installed, but nothing particularly fancy.

[Commander McLane]

Hmm, also this FdL's laser is upgraded to a Mining Laser, as in Cmdr James' case. So probably he is right to assume that the problem may originate from here.

[Influence D]

I've subsequently found other FdLs with mining lasers and a reasonable cost - the difference being, they had other equipment also.

Perhaps it is an artifact of having ONLY a mining laser?

[Influence D]

I've just found another case of this, also with an FdL with just a mining laser.
Some random logging revealed the cause of it:

Fer-de-Lance base_price = 485000

the code then adjusts prices for the cost of weapons:

Code: Select all

price -= [self getPriceForWeaponSystemWithKey:fwd_weapon_string] * 90 / 1000;	// 90% credits

Fer-de-Lance price2 = 484100

Code: Select all

price += eq_price * 90 / 100;

Fer-de-Lance price3 = 484820

Fer-de-Lance price, base_price before cunningFee = 484820 485000
(this is the only ship where price ends up lower than base_price)

Code: Select all

price = base_price + cunningFee(price - base_price);

Fer-de-Lance price after cunningFee = 0

[Influence D]

since it wasn't very clear what I was saying there - this appears to be being caused by an unsigned/signed conversion when the difference between price and base_price goes negative.

if I printf 'value' in cunningFee, I get 18446744073709551616.000000 - which is clearly way, way too big.

I'm not entirely certain how this ends up making a zero total price - perhaps cunningFee bombs out and returns the last value on the stack? perhaps an overflow? I'd assume that it would not be consistent for every OS / build...

a simple patch would be:

Code: Select all

			if (price > base_price)
				price = base_price + cunningFee(price-base_price);
			else
				price = base_price;

alternately, you could just drop the 'else' clause and leave price with its current value, which I have tested and works.

[JensAyton]

Thank you, fixed.