Commodities.plist

Commodities.plist is a dictionary with an entry for each type of market. Three are defined initially, 'default' containing the default (natch) information for each commodity in the universe, 'rockhermit' which has the prices and quantities available at a rock hermit and 'none' which has prices and price variation set to zero.

Each market is an array of 17 commodities, each in itself an array of 10 items:

1. The name of the commodity
2. Units available at a market (this is calculated at each marketplace)
3. Price per unit at a market (this is calculated at each marketplace)
4. The base price per unit MARKET_BASE_PRICE
5. An adjustment to price based on the economy MARKET_ECO_ADJUST_PRICE
6. An adjustment to units availble based on the economy MARKET_ECO_ADJUST_QUANTITY
7. The base quantity available to a market MARKET_BASE_QUANTITY
8. A 'mask' which defines how the price varies MARKET_MASK_PRICE
9. A 'mask' which defines how the quantity varies MARKET_MASK_QUANTITY
10. The unit of quantity (0 == tons, 1 == kilos, 2 == grams)

At each market prices and quantities are calculated from values 4..9 and a random value from 0-255 (MARKET_RND) according to a complex series of steps:-

Code:

 // calculate the local price 
price = (MARKET_BASE_PRICE + (MARKET_RND & MARKET_MASK_PRICE) + (economy * MARKET_ECO_ADJUST_PRICE)) & 255 

// calculate the local quantity available 
quantity = (MARKET_BASE_QUANTITY  + (MARKET_RND & MARKET_MASK_QUANTITY) - (economy * MARKET_ECO_ADJUST_QUANTITY)) & 255; 

// if the quantity gets too high it's zeroed 
if (quantity > 127) quantity = 0; 

// limit the quantity to 0..63 units 
quantity &= 63; 

Thus if you wish the price of a commodity to be higher in good economies you set MARKET_ECO_ADJUST_PRICE to a high positive value. If you require the price to vary less randomly you set MARKET_MASK_PRICE to a low value (1 or 0). You can work out the rest I'm sure!