Ok, I know I’ve had lots of questions here lately but I don’t know where else to go. Iv’e done ALOT of research last couple days and it seems I cant do what I want.
I have a LinetraceSingle() returning a HitResult and I can determine which actor was hit no problem.
I have a Cube blueprint and In that blueprint I want it to recognize it was hit by the trace, and which face was hit.
The line trace comes from a C++ actor component attached to the player.
With a FVector_NetQuantizeNormal, I can store a HitResult.Normal, but only in world space. So if the cube is rotated I get different results.
Another problem with this is all of that is in my linetrace function. I’m having a hard time figuring out how to simply tell the hit actor it was hit, then preform whatever action
its supposed to do from within its own class (or blueprint).
I’m far from a “good” programmer so I apologize if what I’m asking makes little sense. Unreal C++ tutorials are pretty limited.
Thank you.
PS: If anyone out there wants to look at my code and help me fix fundamental problems with it, I’d be more than happy to compensate you with whatever seems fair
You could just get the rotation of the cube, then unrotate the normal using that. You’ll end up with a normal relative to the cube, which seems to be what you want
Another possible solution would be to get the UV coordinates of a HitResult (never used it but heard it was added in some UE version).
From UV coordinates you’ll be able to figure out which side the line trace hit.
Not sure if that is computationally faster then unrotating normals, but can give you more interesting options.
You can easily do this by converting the hit location (which is in world space) to local space (relative location of the cube). Here is an example I made for you.
In your cube blueprint you need to create this:
https://i.imgur.com/KQP38d9.jpg
Then in your character (or wherever you want) you can trace like this to fetch the face ID.
Yea, I keep coming back to simply doing a dot product on each axis, the lowest absolute value one would be the direction then just map that to the appropriate face. Haven’t sat down and worked out the actual math, but I think that would work.
EDIT: You’d also need the raw dot product value to determine which face along the axis was hit, but you would have that already while doing your compares.
Also think about getting the faceIndex (triangle) and the primitive mesh component. If you construct your own mesh or know how the mesh (always) looks like, this will allow you to understand which face exactly got hit. If I create a mesh, I usually use a special array stating additional information about the triangle. This way I can easily look up what exactly was hit. Once you know the triangle you can also determine where on this particular triangle the hit occured. This is one way for example you can calculate a decal.
Hey!
You can mark the line trace as Trace Complex and then can use the face index, where the upper portion of the face will give you a even integer and lower part will give you a odd integer and total 12 integers for 6 faces, Good luck!
