How do I find the topological solution for sculpt-smoothing into a triangle shape?
I am sculpting a trench coat in Blender, and I am having a terribly difficult time finding the topology necessary get sharp looking rips into the fabric.
Every solution I try, like this one for example, will usually produce sharp edges at the bottom of the "triangle", but the top will smooth out into a round shape. This is pretty crap topology, but even more elegant solutions have the same issue.
I am sculpting into the coat with the multiresolution modifier, and will definitely need to do some smoothing in these areas. I cannot just do this via transparency in texturing because the coat is double-sided.
Short video of the issue demonstrating the desired response on the bottom edges of the cut into the coat, but an undesired response from the top: https://i.gyazo.com/115825ef6c428f49e335ec0b9bd74219.mp4
Replies
Use subdivision modifier with crease edge values .
The issue is that it's a whole trench coat with sculpting all over the topside of it. While multiresolution does subdivide it, I can't just use a subdivision modifier for my purposes. The reason I need this is because there's of course all sorts of waves that will come in that loose bit of the trench coat at the bottom.
The rips have to flow with it, so they've got to hold up to sculpting. I'm assuming that this is possible because I'm able to get the corners of the coat for example to stay sharp just fine despite being sculpted on.
Unfortunately creases have thus far not seemed to have much of an impact. I need this both for my current project and for just generally my knowledge of topology for future projects such that I might not run into this issue again. As you can see, that solution in your picture works just fine, but it similarly does not survive sculpting.
Theoretically, I'd be able to just apply this sort of solution after I've finished my sculpting, but sadly it seems the multiresolution modifier does not much like it when you change the topology after you've put some work in.
The thing is that while the multiresolution modifier does just subdivide the mesh, I cannot use subdivision surface for my purposes. There is a lot of sculpting on the top half of the coat, and there will be waves in the bottom of the coat that the rips will need to follow.
The solution you showed works great until it sadly suffers the same fate in that the top point does not survive sculpting. I imagine what I'm trying to achieve here is possible because I can manage to get the sharp bottom corners to stay sharp just fine like in the example I showed in the OP.
Theoretically I could try cutting into the topology like that after the sculpting is completely finished, however the multiresolution modifier does not take kindly to having its topology edited after sculpting has been applied.
To be honest I don't use multires modifier at all. As well as subdivision too except for a few very specific cases. I use dynatopo and remesh settings and fine details only later in textures soft .
I think multires modifier is just a remnant of ancient sculpting approaches .
I don't see much of sculpted details in your coat to care about. Like folds or something. Anyway such things is better to do with cloth physic or cloth sculpting tool. Just an opinion .
I personally choose to use multires both for performance reasons and so that I can maintain a low topology version in shape and skip over most of the retopo process. I'm using a remesh workflow for the face, but using it for everything feels destructive. It's just not showing the details I did on the top of the coat because it's in edit mode.
Odds are I probably should just use marvelous or something for this sort of thing, but I don't have or know marvelous and I might run into this issue with non-clothes objects in the future.
That inside corner will need additional support loops to remain sharp. The width of these loops should be similar to the width of the other perimeter support loops. There's a few different ways to approach the topology layout. As long as everything smooth properly, it's possible to use triangles and n-gons to connect the corner support edges to the rest of the geometry. Since this mesh will be used as a base mesh for sculpting it probably makes sense to try and keep everything on a quad grid.
Here's a couple examples of all quad topology layouts that provide additional support for the inside corner. The first example uses a bit more geometry and since the peak of the cut out lands between the segments the topology is compatible with back to front mirror modifier.
The second example uses a bit less geometry but, since there's a quad connecting the edges around the peak, it won't work with a back to front mirror modifier. Both of these topology topology layouts would probably have to be created before sculpting on the base mesh.
If I end up deciding on some way of just adjusting the geometry after the sculpting (using shrinkwrap or something to copy details from unaffected parts of the mesh, dunno), I'll definitely be using one of those layouts to make sure they subdivide well because they do look good.
Perhaps it is just not possible to get a point like this to just refuse to round out? This corner, for example, will always smooth out into a point.
It cannot be rounded out by smoothing. Perhaps the equivalent just does not exist in a negative form?
https://i.gyazo.com/115825ef6c428f49e335ec0b9bd74219.mp4