- [Narrator] The cut tool,
lets you interactively slice
through any part of a model
and it's very intuitive.
And additionally it will snap
to individual sub objects
that already exist on the model
so you can get clean geometry.
And in this case, we want to employ
it in order to get rid of this problematic situation,
which is known as a concave polygon.
In every corner on this object on these walls
we have this problematic situation
of a concave polygon,
and that is a situation we want to avoid
when we're doing a Boolean.
So the simple solution
to this is just to cut a new edge straight
through here at that corner.
And that will divide this concave polygon
into two convex polygons.
The blue outline around the model
makes it a little bit harder for me to visualize
what I'm working on.
And since I have edged faces turned on,
I know that the object is selected
when those edges are highlighted in white.
So I don't really need the selection highlighting.
That's just kind of getting in my way.
I'm going to turn that off.
There's a keyboard shortcut for that which is Alt-J.
All right, so getting real close here on this corner,
and let's invoke the cut tool.
In the modify panel it's an editable poly object
and the cut tool is found in edit geometry.
So invoke that cut tool.
Now when you hover your mouse,
your cursor's going to change
depending upon what you're hovering over.
If you're hovering over a polygon in the middle of a face,
you'll get a large crosshair.
If you hover over an edge, you'll get this crossbar.
If you hover your mouse over a point or a vertex,
you'll get a smaller crosshair.
So there's a difference between the larger crosshair
which is polygon face and tiny crosshair,
which is a vertex.
We want to snap to vertices.
So we'll get a clean cut right here.
So that's kind of important.
We don't want to accidentally click
in the middle of a polygon,
or in the middle of an edge.
In this case, we want to make sure
we're snapping exactly to a vertex.
And the cut tool has its own snaps built-in.
We don't want to have snaps enabled on the main toolbar.
So make sure that's off.
And then all you need to do is just click on one point.
And then when you move your mouse around
you're not holding down the button,
you're just moving the mouse around,
you'll see a preview of the new edges you're going to create.
We just go down here to this other point,
and click and now we created that new edge.
And when we're done creating edges, right click.
And now we're no longer creating or cutting
but the cut tool is still active.
If you want to make it a little bit easier
to see where these points are,
you can be in vertex sub-object mode,
and now you can actually see the points.
It's not strictly necessary.
You want to go around and cut those edges
on each corner for the top and bottom.
So I'll go over here and I'll notice
what I'm seeing here is actually
some vertices are currently selected.
They're highlighted in red.
So that doesn't really matter,
but I can click half of them in order to unselect them.
So exit out of cut and just click off the model
and click on it again
and then click on it to make sure
I'm not selecting any vertices.
All right so go back to the cut tool,
getting closer and these vertices are in blues
they're not selected,
but I can see them.
So it makes it just a little bit more intuitive.
All right, and then right click
and I just need to do that on all the corners.
Make sure that I have none of those concave polygons
anywhere and we'll need to do that on the top and bottom.
So I'll right-click
to exit that particular cut operation
orbit around with Alt-middle mouse
and pan with middle mouse.
And just repeat that process everywhere.
So that I have none of those pesky concave polygons.
Okay, that's how to use the cut tool
to chop through to create new edges
based upon existing vertices or points.