NOTE: I know this is old.

Hello there.

I don't think you've got your answer since you're asking about dodging bullets (and not general avoidance ai behaviour).

There are many simple ways to deal with that, each one is appropriate for a different scenario.

1- trace a ray from all bullets towards their respective progrades and with the ray magnitude (distance) relative to their velocity PLUS (or TIMES) the inverse of a 'response time' factor. If the ray hits an enemy, you get they outta the way. (MEDIUM SPEED BULLETS)

2- trace a ray(/triangleish/coneish shape if there's spread) from the weapon when the player shoots. If there's an enemy there, move him outta the way. (HIGH SPEED BULLETS)

3- if the bullets are really slow, you could simply loop all of them for each enemy and determine their positions in the future, and add to that the velocity vector of the current enemy being looped, consider a reasonable response time and threshold, if the positions are similar, then don't move the enemy there OR move the enemy outta there. (LOW SPEED BULLETS)

P.S.: I'm assuming you're using a physics engine (box2d, etc) for the 1st and 2nd items.

if the bullets doesn't have 'speed', but are simply raytraces (instantly hits anything), then there's no way other than using the direction the player is facing to somehow determine that (see OriginalDaemon's answer).

I don't think you've got your answer since you're asking about dodging bullets (and not general avoidance ai behaviour).

There are many simple ways to deal with that, each one is appropriate for a different scenario.

1- trace a ray from all bullets towards their respective progrades and with the ray magnitude (distance) relative to their velocity PLUS (or TIMES) the inverse of a 'response time' factor. If the ray hits an enemy, you get they outta the way. (MEDIUM SPEED BULLETS)

2- trace a ray(/triangleish/coneish shape if there's spread) from the weapon when the player shoots. If there's an enemy there, move him outta the way. (HIGH SPEED BULLETS)

3- if the bullets are really slow, you could simply loop all of them for each enemy and determine their positions in the future, and add to that the velocity vector of the current enemy being looped, consider a reasonable response time and threshold, if the positions are similar, then don't move the enemy there OR move the enemy outta there. (LOW SPEED BULLETS)

P.S.: I'm assuming you're using a physics engine (box2d, etc) for the 1st and 2nd items.

if the bullets doesn't have 'speed', but are simply raytraces (instantly hits anything), then there's no way other than using the direction the player is facing to somehow determine that (see OriginalDaemon's answer).