[Tutorial Preview] Gore Mesh & Dismemberment Tutorial

[Chosker]

@n00854180t;572277

I may just make it so that stuff can be multiply-broken. To be honest there’s no reason it can’t do that, it’s just that it would require an additional proxy and ellipse for each sub-break.

yeah that would work.
these proxies, are they also having ragdoll, or how would it look for example a cut arm?

I’m completely fine with implementing the UDK method, it’s just that

1. I don’t know how it works exactly in terms of the code - e.g., did UDK have a broken mesh and an unbroken one, or just the pre-broken one, and it was up to the user to hide the seams themselves (see this post earlier in the thread for issues w/ that)

2. I don’t have any art to test it, and I’m not an artist, so going into a character mesh and cutting the limbs, making caps etc is beyond me.

3. The pipeline is problematic for me personally - copying the weights/updating each character mesh to have broken joints isn’t really feasible for me personally as I have no idea how to do that, and have about 20 character meshes that would need to be redone, and I don’t have the source art for almost any of them.

1. the code itself is what I described earlier: it modifies the vertex weight data at runtime to swap it with the ‘broken’ version of it.
   as for the assets, UDK has an unbroken mesh and a broken one, stored in the same mesh asset (internally it’s probably just a diff list of those vertices that have different weights). as it keeps track of which vertices are associated with which bone, it allows partial swapping (i.e. you can cut an arm at the torso and the other arm will be fine).
   the user had to hide no geometry seams because the bodypart-adjacent vertices are skinned exactly the same (the issues from the screenshot didn’t occur). the only seams came from vertex normal discrepancies and that was only because UDK’s FBX import of SkelMeshes didn’t support custom vertex normals (hope it’s supported in UE4).
   then again vertex normal seams are common in games with paperdolling, like in Skyrim.

2. I have my own art from my UDK game, where I fully use dismemberment. I can provide you with this but only for private testing.

3. for me the pipeline is easier than having to do “pre cut” versions of every body part to use as proxies.
   the requirement is that your meshes need to be separated into detached sub-objects, so that the cut can be clean.
   the other hard requirement is that the broken and unbroken meshes need to have exactly the same amount of vertices/faces, as the swapping is done 1:1 using the vertex indices.
   usually they should also have “stumps” to avoid holes, already as part of the original mesh, but you wouldn’t need them if you do the l4d-style hole filling.
   for me it works like this: for every mesh that can be cut, I make a copy in my 3d software. then I modify the weighting of the vertices at the cutting zones so they only belong to one or the other bone. export, done. for me it’s like 3 minutes per mesh but I’m used to the workflow.

So if you want to supply a mesh I can try this with (base and alt-weights), I can go ahead and investigate implementing a node or some other helper functionality for swapping the weights during break.

I would indeed like to have an alternative to the L4D2 ellipse hiding method because it’s not ideal having to edit the two .usf files. Nor is it very good that the vertex parameters have to carry an extra 12 bytes (float3) of data for every mesh despite only needing it for very few skinned meshes.

I myself would stay away from anything that modifies the engine source or the shaders.

I can provide you with some source art. but actually I’d just do it with the unreal mannequin so you could provide it as an example if you release the code.
but only if you’re convinced that the workflow would suit you