Bevel and Subsurface makes concave corners weird

Question

In hard-surface modeling there are often sharp edges and smooth, flat areas side by side. To get smooth areas, subdivision surface modifier is used. Edges that need to stay sharp, must be surrounded by edgeloops or have to be creased. Manually setting edge loops needs a lot of work and often don't work as expected as edgeloops need to loop the whole object, which creates problems in areas that need to be smooth.

I'm trying to use bevel modifier for edgeloops as this is a non-destructive way to sharpen out edges, furthermore I can control which edges get bevelled by using weights or vertex groups.

In the picture I manually beveled my mesh to showcase the problem.

It seems that when bevelling concave edges, the subdivision surface kinda overlaps the mesh.

Blender file

Previous questions didn't have clear answer or suggested usin edge loops, which don't work in many cases. Is this sort of problem fixable without using edgeloops or creases?

Thanks in advance

Answer 1

There is a very simple solution to that bad topology. Just add two edge loops to fix the effect of the Suburf, see the image:

There's a video of CG Fast Track which talks about this problem. Blender 2.8 Beginner Tutorial - Part 2: Sword. Watch it from minute 41.

Answer 2

• In edit mode
• select the edges
• press CTRLB
• Roll the MMB (mid mouse button)
• turn until you get the number of bevel cuts you want and press enter or LMB (left mouse button)

and that's all the work is done The only thing you should do is practice these types of bevel exercises

Blend Solution

Click in the pumpkin

Answer 3

I had a similar problem with concave angles and subsurface modifier (check Weird behavior when using bevel and subsurf)

You don't necessarily need to add bevels to make the shape look sharper with subsurf. The solution for this problem that I had is very similar to this. Here's what you can do:

• Model the basic shape
• Apply subsurface modifier
• Select all edges that need to be "sharp"
• Select all edges that are connected to the problematic area
• Add them to a new Vertex Group
• Add a bevel modifier before subsurf, set it to 2 or more segments
• Change the method to Vertex Group
• Select the vertex group that you just created, you should end up with something similar to this:

Edit

I noticed that the final result has some undesirable edges along the side of the model. To fix this, work the topology like so:

• Select these edges

• Add a bevel

• Work the topology by dissolving edges and merging vertices to look like this