Search in
Sort by:

Question Status:

Search help

  • Simple searches use one or more words. Separate the words with spaces (cat dog) to search cat,dog or both. Separate the words with plus signs (cat +dog) to search for items that may contain cat but must contain dog.
  • You can further refine your search on the search results page, where you can search by keywords, author, topic. These can be combined with each other. Examples
    • cat dog --matches anything with cat,dog or both
    • cat +dog --searches for cat +dog where dog is a mandatory term
    • cat -dog -- searches for cat excluding any result containing dog
    • [cats] —will restrict your search to results with topic named "cats"
    • [cats] [dogs] —will restrict your search to results with both topics, "cats", and "dogs"

Trigger Collision is colliding with AI characters

Since 4.9, I have strange issue with grenades. I have two big radius collision spheres as components for the static mesh (grenade). The grenade collide the right way with enviroment, but those collision spheres collide with AI skeletal mesh actors even I have set the collision as trigger and also tried with overlap all. If I disable the collision for spheres, the grenade fly correct again.

I tried to enable those spheres when the grenade is about to explode (so can check nearby actors), but even I enable only query the nearby AI actors get pushed away from the collision area. Using mixamo fuse characters if that have some strange effect.

Product Version: UE 4.9
more ▼

asked Oct 07 '15 at 10:05 PM in Bug Reports

avatar image

333 17 33 42

(comments are locked)
10|2000 characters needed characters left
Viewable by all users

1 answer: sort voted first

Hello SaOk,

How do you have the collision on your AI set up? Are you ensuring that it is not set to block your grenade's collision?

more ▼

answered Oct 08 '15 at 07:12 PM

avatar image

Sean L ♦♦ STAFF
43.5k 485 152 442

avatar image SaOk Oct 08 '15 at 08:29 PM

AI characters have capsule set pawn and skeletal mesh as character collision. Those shouldnt block the grenade trigger volume when the grenade trigger volumes have overlap all setting, but they do.

avatar image SaOk Oct 08 '15 at 08:36 PM

Update - Its the pawn collision that blocks those trigger volumes. I set collision to "ignore only pawn" for the trigger volumes and seems I can now manage proper grenade behaviour that way. Still seems like a small bug?

avatar image Sean L ♦♦ STAFF Oct 08 '15 at 08:40 PM

The character mesh is set as a Pawn object type by default if you have a look at the expanded Collision tab in the character blueprint. This is why you'd have to set your collision to ignore the pawn in order to prevent the object and the character from colliding. Any time you want to have two objects interact with one another, each object's collision needs to be set in such a way that they are able to either collide, overlap, or ignore one another. Hope that helps explain the reasoning behind your issue.

avatar image SaOk Oct 08 '15 at 09:18 PM

Yes, but it seems pawn still collide even the colliding object have collision that should overlap pawn. So overlap pawn setting seem to work wrong since 4.9 for me. Ignore pawn works, but not overlap pawn.

You could test it by creating physic object that have big volume around it with overlap pawn collision setting. If you walk to the object it should move before reaching it.

avatar image Sean L ♦♦ STAFF Oct 08 '15 at 09:19 PM

Are you sure that the pawn is set to overlap whatever the grenade's object type is?

avatar image SaOk Oct 08 '15 at 09:44 PM

Yes, 100% sure :)

Grenade static mesh (physicActor) overlaps dynamic and pawn. Volume (component for grenade) overlaps all.

AI actor capsule (pawn) overlaps physics, dynamic and pawn. Skeletal Mesh (component for capsule) also overlap the same as capsule.

avatar image Sean L ♦♦ STAFF Oct 09 '15 at 01:00 PM

I've done some investigating, and it turns out there is actually a bug in our system, UE-21559, that relates to sphere components and player capsules having some collision issues, which could explain the behavior you were experiencing. Is it possible for you to either create a video, or zip up a test project that shows the bug so that we can confirm that it is the same bug? Thank you.

avatar image SaOk Oct 09 '15 at 02:52 PM

Hi, yes sounds like the exact same bug. Its the capsule that collide with the sphere, not skeletal mesh. Also box component is having the same issue. Made video, bit bad vid but you can see the bumerang effect unless not throwing at the AI characters. https://youtu.be/SGypP8kH5m8

avatar image Sean L ♦♦ STAFF Oct 09 '15 at 03:00 PM

Could I get a screenshot of the components tab of the grenade blueprint? Try using a scene component as the root, and then parenting the mesh and the volume as children of the root.

avatar image SaOk Oct 09 '15 at 03:15 PM

Sure here, for sphere also have tried overlap all dynamic, overlap only pawn, trigger and custom. Also object type world dynamic.

EDIT: Will try that scene component as root.

alt text alt text

ue4bugpic1.png (268.4 kB)
ue4bugpic2.png (270.2 kB)
avatar image Sean L ♦♦ STAFF Oct 09 '15 at 03:46 PM

I have tried to reproduce your issue in a new project, but was unable to. Could you try to create a new project with just the character and grenade and see if you still have the same issue? If you are having the issue, please zip up the project and send it my way so we can have a look at it and see exactly what the issue is. Thank you.

avatar image SaOk Oct 14 '15 at 11:14 AM

I tried to have scene component as root, but couldnt make the grenade fly then. But as strange effect, when I returned to old structure (as in that pic) now the grenade seem to work as intented. Overlap all for sphere no longer collide with pawn. :S

avatar image Sean L ♦♦ STAFF Oct 14 '15 at 12:41 PM

Did you make any changes when you re-did your old structure after trying the scene component as the root, or did you reset it to exactly what it was?

avatar image SaOk Oct 14 '15 at 04:02 PM

Just removed the scene and moved the old components to have old structure. But earlier I made the pawn to ignore physics actor. Could be the sphere in grenade was somehow detected as physicsActor even only its root (the mesh) is physicsActor. Seems like it inherited the root collision settings.

(comments are locked)
10|2000 characters needed characters left
Viewable by all users
Your answer
toggle preview:

Up to 5 attachments (including images) can be used with a maximum of 5.2 MB each and 5.2 MB total.

Follow this question

Once you sign in you will be able to subscribe for any updates here

Answers to this question