Hello All,
Is it possible to break only a specific part of a mesh?
For example:
if I have a wall or a floor mesh and I want it to destruct in a path from point A to point B ?
like a crack in the floor for example?
Thanks ahead and Sorry about my bad English.
Yes this should be possible, but would require a little setup and depending on your final need.
If you want an animated style where pieces fallout after another you can do this as an animation similar to this: Unreal Engine 4 "Elemental" Demo Running on PlayStation 4 - YouTube
If you want it to just have parts fallout in a specific area of the DM you can could use a combination of Support Depth (set to 1), chunk parameters for Do Not Fracture, and setting the Damage threshold to a value that’s needed.
Once the Dm has been setup you could use some radial force actors along the path of the DM where you want these to be affected to apply the damage to remove them.
It shouldn’t be too difficult to setup and if you need further help with it just let me know and I can help. 
Thanks Tim,
That’s what I’m trying to accomplish!
The thing is that I’m still new to UE4, and the other thing is that I want it more for Cinematic purpose like in the demo. (not for a game) so maybe it’s different or the same process I have no clue how to get started.
I’m still exploring / testing the basics of it thanks to video tutorials from UE4.
Is there a video-tutorial on such thing you can share?
Sure thing! any help will be very appreciated Tim, but since I’m a noob I think that only a visual step-by-step video tutorial is the best way for me to learn so far (also because of my bad English).
I don’t even know how to start, I think the best way is from a simple cube… to emulate a floor or a wall, unless I should export/import a specific mesh with vertex groups or something like that from Blender.
I’m fully inspired after watching this demo and hope that I can do something simple based on this idea…
also hopefully my hardware can handle this madness, I have no idea.
I see you’re using Blender and all this should be possible there as well. Essentially, if you want it only for a cinematic type thing you can just create the physics simulation in the modeling application. When the physics simulation is baked to your timeline you can then select all the fracture pieces and place them in a “group.” Once they’ve been grouped you can export the FBX with the animation into UE4 and it will play as a rigid mesh animation.
This process was used throughout the Unreal Engine 4 Elemental demo for the rocks falling and breaking, and the ice splitting down the middle.
I’ve setup a simple tutorial with this in one of my threads here: [TUTORIALS] Photons Be Free: Mini-tutorials and other curiosities - Community & Industry Discussion - Epic Developer Community Forums
This method uses 3Ds Max, but should be similar in other programs. I mostly go through the process of getting it into UE4 rather than discussing how to create the physics simulation. There are videos on YouTube that show how to do all that side of things.
For this second one I’ll try and make some time this afternoon to setup something simple as a demonstration. If you want to create a floor or wall it’d probably be best to just use a custom mesh from Blender that is the size you need. For the demonstration I’ll just use a BSP that is converted to a static mesh and start from there. It shouldn’t be too difficult. I’ll try to record a video when I do it, but no promises. I’ll try and be as clear as possible with steps to help though if I can’t.
If you want something like the Elemental Demo that’s a lot of particle effects in addition to some destruction. It’s a combo method that is used often when creating these types of assets or effects. Games have to fake reality often and here is no exception. 
Thanks for the detailed reply Tim, I appreciate it!
I will check out that link, hopefully I will be able to understand it.
I thought that I can setup the mesh in a way that the fracture will have a real-time control for example if I’ll move an “invisible sphere” or any other object that will collide the path and start the destruction, but if I understand from you it’s all baked on the 3D software and imported. I’m still confused but I’ll have to explore more of course.
The particles, smoke, dust, etc… is definitely something I want to combine with it, but first I think I should understand how the mesh destruction works and only than mess with the particles which is something I can’t wait to get into as well.
If you’ll make a video tutorial I’ll make sure to check it out, and I bet it will be very helpful for other UE4 users.
I may ask more questions in this thread but first I’ll look around and also in YouTube as you suggested.
Yeah no problem. Ask any questions you have.
If I do set something I try to take it with that approach that I can make it available for others as well. That’s kind of why I started that thread with some things of interest that I’ve worked on since my time with Epic. No since in it just going to waste on my hard drive. That’s certainly not helping anyone.
Typically I prefer written tutorials over videos, but I’ll see what I can do.
That’s very kind of you Tim!
I respect and like that people can share information with the community to learn new things. 
Video Tutorials are easier for me to follow because I can see every single step usually and maybe it’s my brain who can understand it better hehe.
OK, so back to the subject:
Just to be clear, I don’t have a specific idea for the effect yet but I know that I will use it for sure in UE4.
I’m a bit confused with: the Real-Time destruction in UE4 V.S. baked animations and import to UE4.
Since UE4 is still new to me I’m still “afraid” of it a bit hehe (like any new software), I’m learning as much as I can with the video tutorials but I’m trying to focus and cover more subjects related to the UI and the visual / cinematic parts because my highest priority in UE4 now is to make cinematic, instead of render in Blender.
Do you think for a simple “TEST” is it possible to make a simple floor cracking (like in the demo but much simple) 100% inside UE4?
If I understood from you, the best is to animate and bake the full animated floor, but is it better than keep a real-time result inside the engine?
As you can see I’m very confused, please don’t get me wrong I’m not complaining, I appreciate a lot your supportive spirit and patience with my bad English and probably… stupid questions. 
Meanwhile…
I’m now messing around with a simple sphere and doing the most simple destructible test by letting it fall and break into parts… so far so good, it works and it was easy to do.
Your English is not bad and there are no stupid questions here.
If you need a very specific look and aren’t looking to use any real-time physics simulations then a physics simulation baked and imported as an animation would be ideal. This isn’t real-time and you get the best results that are reproducible every time without question.
If you just want a destruction effect that a player can trigger and it’s physically simulated in real-time in UE4 then using the destruction tools available in UE4 are a way to go about that.
I would say a simple floor cracking and falling is not too difficult to setup with a Blueprint and have it triggered to have pieces crack and fall away when the player gets close. The idea behind this is that it’s fully interactive and depending on factors in the game environment these can affect if the destruction.
Thanks Tim!
You put some sense in my brain, I think that the baked animation will be ideal for me as you recommend.
I’ll try to make something simple in Blender and bake it.
So, once I’ll have the FBX exported and ready to use in UE4 (baked animation with all the keyframes).
Do I import to the content browser just like I would do with any other object OR do I need to import it inside the DM editor?
which doesn’t make sense because I need to create a DM first I guess (I may be wrong).
This will actually take me a little bit longer than I had thought. My initial tests worked OK, but not exactly the way I was hoping. Isn’t that always the way it goes though. 
Really the best results are going to be an animation in Blender or whatever modeling application and then exported and imported into UE4.
If you bring that into UE4 that will import as a skeletal mesh. No need to bring in as a DM.
A destructible mesh created in UE4 is not the same thing as an animation of a destruction so it won’t be considered a dynamic destructible that can move around the scene with separated chunks.
I could do a video of that process, but since you use Blender and I’m on 3Ds Max it may be more confusing.
As for the destructible mesh in UE4 I’ll play around with this over the next week or so when I get time and see what I can come up with that may look halfway decent. Should be doable, but it’s not something I’ve setup previously so I’ll have to work out the kinks and go from there.
Thanks again Tim!
I’ll keep playing with it and keep update in here if I have a question or a “TEST” update to share the results.
hi,
my apologies if this question is not for here, but I have not found solution elsewhere.
I am trying to simulate a machining process to show material removal. something like this link: Tech Tip - SOLIDWORKS CAM Getting Started - YouTube
in 2:30 it shows the cutting process and that’s what i’m trying to do. i have used box collision+decals+texture of a hole/other shapes during the process, but it just doesnt work properly.
does any one have any idea about how to do such a thing like in the video?
any help is greatly appreciated