AI See Player

I'm making an ai behavior where the agent will attack the player when it "sees" him. My question is what is the best way to make the agent see.

 

Test for proximity and direction, if close enough and in the right direction fire a few rays out to check if anything is in the way.

 

I would use a collider to detect if the player is in range, then either:

A) Start sending out raycasts directly forward of the enemy's head until you see the player. You could also use a SphereCast to simulate a cone of vision / field of view.

B) Do a simple angle compare until the angle between the enemy forward and the vector to the player is within the cone of vision you want to use, such as +/-10 degrees.
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I can't resist a shameless plug. TargetPRO can do this work with a couple of components:
http://forum.unity3d.com/threads/13...-logical-Games?p=953417&viewfull=1#post953417

 

Yeah collider is fine for the first step too, better in many ways (slightly less efficient, but much simpler/cleaner code).

 

I would think it is more efficient since it is passive when the player isn't in range.

 

Okay, that sounds like it'll be simple to do, thanks.

The agent will be able to hear as well could that stand in for the first step?

 

And how do you think the physics engine determines if something is in range? Magic?

EDIT: Of course there are many optimisations (e.g.sleep), but in the end the physics engine is still going to have more effect on frame rate than a single distance check done each frame.

But anyway, I agree your solution is better, its what I use in my own turret defence game!

 

That is up to you and how you want to implement it. You could add a child object that has a smaller collider for the hearing range, and another child with a larger collider for the visual range, I suppose. You could use a simple OnTrigger in each child's script to notify the parent when it is time to act.

 

Yes

Triggers are supposed to be very light. I'd love to see some tests, but honestly i have never seen it impact performance and I have a lot running at once: turrets, projectiles, enemies, etc.

 

Not likely to be any real issue but compare it to a vector sqrMagnitude calculation.You can do several million of these in less than second on an old PC.

Edit: A very rough test ...

5000 enemies (cubes, non kinematic rigidbodies, on a layer that doesn't collide with itself and spread out on a 50x50 area), 1 player (sphere collider with trigger radius 10), enemies drift randomly. FPS on my machine ~5m/s

Remove all physics components and loop through each enemy doing Vector.sqrMagnitude on the difference of positions ... ~80fps.

Do no calculation ... ~80fps

 

Interesting. Wouldn't it be more accurate to test with isKinematic (rigid body) and isTrigger (collider) set to true? This should be the lightest use of the Physics engine.

Thanks for taking the time to have a cursory look. I wish I had it!

 

Anyone framiliar with Rain One AI?
I am working on a FPS and am
Looking for someone to assist me with setting it up.
I'm brand new to the world of scripting and don't really know where to start

 

Sorry the bodies were *kinematic*, not non-kinematic.

I'm not sure making the other colliders triggers would have much effect on performance (as they don't collide with each other), but will check it out.

- Johnny A