# Line Trace not Blocked by Physics Asset: Why?

**URL:** <https://forums.unrealengine.com/t/line-trace-not-blocked-by-physics-asset-why/2651183>\
**Category:** Programming & Scripting\
**Tags:** line-trace, unreal-engine, Collision, question\
**Created:** [August 26, 2025, 6:01pm UTC](https://forums.unrealengine.com/t/line-trace-not-blocked-by-physics-asset-why/2651183 "2025-08-26T18:01:43Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![jyelon](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@jyelon](https://forums.unrealengine.com/u/jyelon)\
**Post date:** [August 26, 2025, 6:01pm UTC](https://forums.unrealengine.com/t/line-trace-not-blocked-by-physics-asset-why/2651183/1 "2025-08-26T18:01:43Z")

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I’m trying to get a line trace to hit a physics asset. I’ve configured everything in a way that I think is correct, yet the line trace just goes right through the character as if the character wasn’t there.

Here is my blueprint:

 ![lt-blueprint](https://d3kjluh73b9h9o.cloudfront.net/original/4X/6/1/9/619d5cbada0efc199cd6354be4c0a73c51a9c16f.png)

The helper function Line Trace Through Pixel really just calculates the start and end position, then calls Line Trace by Channel:

 ![lt-utility](https://d3kjluh73b9h9o.cloudfront.net/original/4X/5/3/3/533367b6a26b0a5b097cf2577f968e104406c5ac.png)

Here are the collision presets for the skeletal mesh component:

 ![lt-charcoll](https://d3kjluh73b9h9o.cloudfront.net/original/4X/d/7/f/d7f77f1a0be7099c816530923fd80b38f07bfbe6.png)

It seems to me (as a newb) that these settings ought to work: the ray ought to hit the physics asset. But when I turn on ‘Show Collisions’ in the viewport, and also ‘Draw Debug Mode’ for the line trace, I can see the line trace go right through the character physics volumes without hitting.

Note that the character I’m trying to hit is pretty much just Quinn. The character is adapted from one of the template games, the skeletal mesh is SKM\_Quinn\_Simple, and the physics asset is PA\_Mannequin.

I’ve previously been advised to turn on/off ‘Trace Complex’. I’ve tried it both ways, no difference.

I’ve also been advised to turn on ‘Enable Per Poly Collision.’ That does cause the line trace to hit the character, but it’s also very slow. I’d rather use collision volumes.

Any idea why the line trace doesn’t hit the physics asset?

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**Author:** ![nande](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/nande/32/1057698_2.png) [@nande](https://forums.unrealengine.com/u/nande)\
**Post date:** [August 27, 2025, 3:07am UTC](https://forums.unrealengine.com/t/line-trace-not-blocked-by-physics-asset-why/2651183/2 "2025-08-27T03:07:17Z")

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“end = start + distance”

i think this will work, but you should make sure the coord system is positive forwards.

i would disable trace complex. at least until you can get it to work.

can you also share the settings for “LookAtDirection” channel in the settings?

also share the code for setting “TraceChannel”. i get the feeling that might be not great.

here’s my code for tracing [Making sure you're not a bot!](https://codeberg.org/jerobarraco/Interact/src/branch/master/Source/Interact/CInteractor.cpp)

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**Author:** ![jyelon](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@jyelon](https://forums.unrealengine.com/u/jyelon)\
**Post date:** [August 27, 2025, 10:33pm UTC](https://forums.unrealengine.com/t/line-trace-not-blocked-by-physics-asset-why/2651183/3 "2025-08-27T22:33:56Z")

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I am 100% certain that my trace start and trace end positions are already correct. I can turn on “Draw Debug” for the line trace and I can see that it’s drawing the trace in the right place. Also, if the trace hits a static mesh, it works perfectly. So this isn’t the problem.

As I explained in my initial post, I’ve turned “trace complex” off. Didn’t make a difference.

The initial post contains the setting for LookAtDetection, it’s there in one of the images.

The initial post contains the code for setting trace channel. Again, it’s in the images.

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<div class="post-metadata">

**Author:** ![nande](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/nande/32/1057698_2.png) [@nande](https://forums.unrealengine.com/u/nande)\
**Post date:** [August 27, 2025, 10:39pm UTC](https://forums.unrealengine.com/t/line-trace-not-blocked-by-physics-asset-why/2651183/4 "2025-08-27T22:39:29Z")

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hello, i see you’re frustrated by this, i’m just trying to help, it’s important to make sure of certain things.

> [@jyelon](#):
>
> So this isn’t the problem.

great.

> [@jyelon](#):
>
> I’ve turned “trace complex” off.

great, i’ve read that, i meant to _keep_ them off. make sure you don’t enable them again until it works.

> [@jyelon](#):
>
> The initial post contains the setting for LookAtDetection, it’s there in one of the images.

i think you’ve miss understood, i meant this.

 ![image](https://d3kjluh73b9h9o.cloudfront.net/original/4X/0/f/c/0fcea1c70b2802782151fdb3c53b46aaf11ff3cb.jpeg)

maybe make sure that your channel is a trace channel and not an object channel.