Incorrect substraction from in stock or demand when using +10% or -10% buttons from station's lobby

[Max5377]

Observed behaviour

Selling or buying fuel in station's lobby using +10% or -10% buttons incorectly substracts it from in stock or demand respectively. For example, when I sell 3t of fuel it will subtract 2t from demand, and when buying 2t of fuel, it will substract 3t from in stock.

Expected behaviour

Selling fuel and buying fuel should correctly substract corresponding columns.

Steps to reproduce

1. Go to commodity market;
2. Remember Hydrogen in stock and demand;
3. Go to lobby, watch how much fuel you have now;
4. Sell or buy fuel using +10% or -10% buttons, watch how much it substract or adds it to you ship fuel;
5. Compare this with in stock(buy) or demand(sell).

My pioneer version (and OS):
Latest master build (ac06900) (Windows 10 x64)

[sturnclaw]

Selling fuel reducing demand is correct, and is intentional to prevent market simulation exploits. Buying fuel from the market should not increase the amount of fuel in stock though, will look into that.

[Max5377]

@Web-eWorks My bad. Buying fuel correctly substracts it from in stock. But what's wrong is that for example, I have Coronatrix with 23t of fuel. I sell it using -10% button. This will substract 3t of fuel from my ship, but will substract 2t from demand instead of 3t(23t from my ship - 10% = 2,3). Same issue with +10% button, if for example I buy fuel using this button and it adds 2t of fuel to my ship, it will substract 3t of fuel from in stock(18t from my ship + 10% = 1,8).

[sturnclaw]

This is most likely caused by an incorrect fractional value of stock being passed to SpaceStation:AddCommodityStock in SpaceStation.lua.

[Max5377]

@Web-eWorks
Pioneer\data\pigui\modules\station-view\01-lobby.lua in local refuelInternalTank
The problem really was with AddCommodityStock, more specifically, in this line in refuelInternalTank:

station:AddCommodityStock(Commodities.hydrogen, -math.ceil(mass))

math.ceil is rounding number up, so if this number is negative(ex. -2.3) it will be rounded to -2 because it is nearest value that greater or equal to -2.3. So the solution is to change above mentioned line to:

local commodityChangeAmount = mass < 0 and math.floor(mass) or math.ceil(mass) station:AddCommodityStock(Commodities.hydrogen, commodityChangeAmount)

Accepted answer by Guffa(albeit it's for javascript, but works the same way)

[impaktor]

Good find. If you're interested in hacking pioneer's code, this is a good first pull request to learn the process. If not, we can push the fix.

[Max5377]

I'll try to do that.