2

I am trying to add a boolean modifier to a cube, cut a hole in a face but it does not appear to be working.

Even though I'm a newbie I'm sure I'm using the modifier correctly.enter image description here

Jkmail
  • 381
  • 3
  • 5
  • 14

3 Answers3

6

You can't see the result of the boolean operation because both meshes are visible. If you disable the visibility of the cutting object you can see the result of the boolean operation.

enter image description here

But you should really try to avoid using booleans for simple operations like this. Booleans will create very messy topology that will give you headaches down the line. There is a indeed a time and a place for booleans, but if you are starting with blender, start on a more solid footing by learning other ways that will yield proper topology.

Watch https://www.youtube.com/watch?v=Bc52fcrHvAA

  • I watched the videos and understand what is involved but as a newbie, it seems very complicated. Your suggestion to hide the visibility did not work, – Jkmail May 21 '19 at 03:42
  • to help you further please explain what happens. "didn't work" is not useful if you don't inform us what result you got instead. Use the edit link at the bottom of your post and add additional information and images updating what you tried. –  May 21 '19 at 03:56
2

You won’t see the hole in the face of the cube until the modifier is applied. One way to see if the boolean worked is to display the appearance of the cylinder as a wireframe. To do this go in Properties editor > Object > Display> Wire. Or check this link on how to make objects transparent.

How to make objects draw transparent/wireframe in the viewport?

I don’t use the boolean modifier that much because it destroys the topology of the surface(s) where the boolean is applied but there are ways around it to fix it.

Hyun Moon
  • 111
  • 2
  • 6
  • You don't need to "apply" the modifier to see the hole. Just hide (or restrict visibility) on the cutting object. –  May 20 '19 at 23:48
  • If he is leaving the face as it is he doesn’t have to apply it and can hide the cylinder but if he is modeling on top of it and want to use the vertices of the cutted face well he has to. I wouldn’t recommend using booleans tho. – Hyun Moon May 20 '19 at 23:58
  • If you don't recommend using a boolean modifier how would you cut a hole in a mesh how would you do it? – Jkmail May 21 '19 at 02:59
  • @BlendweMS I use Looptools to make holes in a mesh. I learned how to use it by watching tutorials on youtube. Here's one: https://www.youtube.com/watch?v=DSwTexnPDa0

    I'm also a newbie but I watched different ways of making holes in a mesh, this is one of many so it might be useful to you or not depending on what kind of model you are making. I like to watch people speed model to see what kind of methods people come up with and copy them. See if it works for you lol and have fun

     – Hyun Moon May 21 '19 at 04:01
2

Well, part of your problem could be that the default cube has no thickness, and of course you can't see the hole made by the boolean modifier if the cylinder is rendered solid.

Here you see what I mean, and how to solve:

enter image description here

Changing the cylinder to "wire" lets you see the hole, but the hole is wrong because the cube has no thickness. Adding a solidify modifier and putting it before the boolean makes a much better hole.

m.ardito
  • 11,967
  • 2
  • 23
  • 36
  • Why add a solidify modifier ?? –  Jul 09 '19 at 16:40
  • This is the correct answer. Blender will cut 2-dimensional holes into 2-dimensional meshes (i.e., planes), but as soon as you have a mesh that is extended in all three dimensions, Blender tries to be smart and treat it as though it was a "closed" even if it isn't (not sure how exactly, convex hull?). You can test this by boolean-cutting a hole into an ordinary plane vs a plane with one edge extruded out-of-plane. Solidifying "actually" closes off the mesh so Blender will make holes into these closed-off volumes. Not sure how it all works in detail but that seems to be the general idea. – smheidrich Jun 03 '21 at 05:54
  • The documentation also mentions this (emphasis mine): "Only Manifold meshes are guaranteed to give proper results, other cases (especially “opened” meshes, Non-manifold but without any self-intersections) will usually work well, but might give odd glitches and artifacts in some cases." – smheidrich Jun 03 '21 at 05:55