Hmm, I just noticed something interesting that I feel I should add. The probabilities for a meteor hit are not the same as the probabilities for a missile hit.
Un-upgraded Meteor Defense
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50% EMP Missile
50% Small meteor (size = 0)
40% Medium meteor (size = 1)
30% Large meteor (size = 2)
Upgraded Meteor Defense
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75% EMP Missile
75% Small meteor (size = 0)
60% Medium meteor (size = 1)
50% Large meteor (size = 2)
The range in any case is 20 tiles. (If (distanceApproximation <= 20 tiles) Then fire). The range is calculated at the point when the miss/hit is determined. Remember that the missile/meteor is moving as it comes in. The hit checking time seems to vary somewhat. This implies that the exact range will also vary accordingly. This means that the faster the object is moving, the shorter the effective range of the Meteor Defense. Similarly, if the miss/hit is determined longer before the actual point of impact, the shorter the effective range of the Meteor Defense. (i.e., the object is farther away when the miss/hit is determined).
EMP Missile: (12 < actionTimer <= 20) => [13..20] (With the 1.3.5 Beta 2 Meteor Defense patch) [13..20 ticks?]
Meteor: (actionTimer == 2) [16 ticks?]
The only problem with the above actionTimer values, is that they don't necessarily correspond to ticks. In some cases, certain functions that would decrement the timer would only be called every 1, 4, or 8 ticks. Also, it's possible that some code may double decrement the timer before returning. I believe the EMP Missile may have it's timer decremented once per tick. I believe a meteor has it's timer decremented every 8 ticks.
A meteor moves 15 pixels left, and 11 pixels down on each tick. (-15 x, + 11 y).
An EMP Missile doesn't "move" while landing. ( +0 x, +0 y). It's graphics are offset based on how much time is left before it lands (20 pixels down per tick), but this is not taken into considering when determining distance from the Meteor Defense.
