Stockpiling

Stockpiling is a new way that secondary industries process cargos. All my industry GRFs use stockpiling.

Original TTD industries have instantaneous processing; you deliver some cargo, and the cargo is instantly transformed into whatever that industry produces. With stockpiling, the incoming cargos are stored, and then gradually transformed into the outgoing cargo.

This allows for a number of new behaviours:

• It is possible to overwhelm an industry, by supplying more raw material than it can handle.
• Industries can require more than one cargo, and only process when they have both (eg, the steelmill requires iron ore AND coal).
• Industries can adjust production level based on a number of factors (eg, the amount of cargo waiting, or if any cargo was transported away last month)
• Industries can change graphics based on waiting cargo.