Explanation of Empire At War's AI "engine"

Drieick

Category: Coding Level: Intermediate Created: Monday February 25, 2008 - 3:03 Updated: Monday May 5, 2008 - 22:43 Views: 6349 Summary: Taken from the forums, a tutorial on EAW's AI

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Basic expression syntax
It's quite simple, really. You basically just follow the order of operations found in math. All you really need to know are the operators:

* = Multiply/can be used as a form of an "If" statement
+ = Add
- = Minus/Subtract
/ = Divide
> Greater than
< = Less than
() = Blocks of expressions which end up as one value
# = Unknown/I'm not sure what this operator means

The mulitply, I think, is the hardest to get used to, but it's quite easy. It can be used to multiply or an "If" statement. How? Well, remember how each function returns a value? Well, if one expression in that function require something and that requirement isn't met, then it returns 0; if it's true, then returns 1. Something such as this...

(Variable_Self.BaseLevel > 0)

...will return 0 if it's false and 1 if it's true. What's the point? The multiplication. If the statement is false and it's multiplied by something, then the result is 0. For example:


<Allowed_To_Retreat_From_Space>
    Game.IsCampaignGame
    *
    Variable_Self.CanRetreat
    *
    (1.0 - Variable_Self.IsFaction {Parameter_Faction = "Pirates"})
</Allowed_To_Retreat_From_Space>


If Game.IsCampaignGame returns 0, then the function returns a 0, no matter what the other values are. If Variable_Self.CanRetreat returns 0, but Game.IsCampaignGame and (1.0 - Variable_Self.IsFaction {Parameter_Faction = "Pirates"}) return 1, the whole thing is 0: 1 * 0 * 1 = 0.

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