How do I use an enemy's OnTriggerEnter to collide with stationary player?

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I have a player ship and many enemy ships (prefab). I want the ship to collide with enemies (ship takes damage, enemies are destroyed), but I don't want enemies to collide with enemies (don't want them to destroy each other).

Here's how I have tried to do this. Ship and enemy prefab have Colliders, ship has a Rigidbody. Ship is the Trigger. I use OnTriggerEnter in the ship's script.

Problem: if the ship is stationary, enemies pass right through it.

How do I get enemies to ignore each other, but collide with the the stationary ship? If I need to use Triggers then I will. If I shouldn't use Triggers, please tell me that also.

Answer 1

Best Answer

Answer by aldonaletto · Jan 24, 2013 at 04:16 AM

Simply add kinematic rigidbodies to the ship and the enemies: trigger events will be generated no matter if the ship is static or moving.

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brag42 · Jan 24, 2013 at 06:49 PM 0

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@aldonaletto: Thank you for your answer. I made the ship kinematic and now the enemies collide when the ship is stationary. After your suggestion, I read about non-kinematic collisions and found out they "fall asleep" when stationary. That's why the enemies pass through my sitting ship.

aldonaletto · Jan 24, 2013 at 10:37 PM 0

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I suspect that the reason is different: apparently, the collision system only tracks rigidbodies (kinematic or not), thus it can detect when a rigidbody hits a collider, but not the other way around. As a rule of thumb, any moving collider should have a kinematic rigidbody for the collision system to work. Non-kinematic rigidbodies "go to bed" when not moving in order to reduce the CPU load, but they wake up when another rigidbody collides with them.

brag42 · Jan 25, 2013 at 08:07 PM 0

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@aldonaletto: I didn't think it would work to put a Rigidbody on the enemy prefab too, but it did. It's working exactly how I want it to. Now I just need to understand collisions and triggers better. Obrigado, Aldo!

Maskeowl · May 03, 2021 at 06:36 PM 0

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I want the exa$$anonymous$$er in an area to perceive that there are no enemies around, but when he detects the player, he immediately opens the door, even if there is an enemy inside, how can I fix it?

Answer 2

Answer by cdrandin · Jan 24, 2013 at 03:48 AM

This should help you http://docs.unity3d.com/Documentation/ScriptReference/Physics.IgnoreCollision.html

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brag42 · Jan 24, 2013 at 03:52 AM 0

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@cdrandin: Thank you, that looks very useful. I need to go try it out.

How do I use an enemy's OnTriggerEnter to collide with stationary player?

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