Cut, weld, and extract to modify topology

00:03

To develop this bottom edge of the side panels,

00:06

the topology will have to reflect all of these different directions.

00:10

And for this, I can use the Cut

00:13

the Weld and Unweld and the Extract tools.

00:16

So I'll need an extra face down here, so I'll just use Extrude

00:21

and make sure that's set to Subdiv Edges.

00:24

And this will weld to the origin edge but not to the side here.

00:30

So I can do that manually using the Weld tool.

00:34

And To Target means that I pick one vertex or edge

00:38

and then ask it to move and join to this one.

00:41

Or if I undo that

00:44

To Midpoint finds the center position.

00:46

And so I can just drag-select the vertices to join them in the middle.

00:52

And to show you the Tolerance option first, I'm going to use Unweld.

00:56

So if I wanted to separate out this fender, for example,

00:60

I could pick this edge loop and then choose Unweld.

01:03

And you can see that it's now a separate SubD.

01:08

But if I undo just the move,

01:11

these are still separate subdivs with the vertices pretty much coincident

01:16

and certainly within this tolerance.

01:19

So when I box-select and let go,

01:22

only the close or coincidence CVs are welded.

01:28

Over here on the hood, I could use Unweld again,

01:31

but I can also just pick the faces and do Extract

01:35

with Keep original off.

01:37

Then it works just like a cut and paste for SubD faces.

01:42

And then at this frontage,

01:45

if this time I use Extract with Keep original on,

01:49

then it's the equivalent of a copy and paste

01:52

because the normal copy and paste tools don't work on subdiv faces,

01:56

so we use Extract instead.

01:58

And then I could use that to start some new geometry

02:02

which starts out with the same structure and shape as the hood.

02:06

So Weld and Extract work within the existing topology and edge flow.

02:11

But if I now go back to the body side

02:14

and just get this angle how I want it.

02:18

I'm wanting to create an indent feature here.

02:20

So I'm going to need to change the flow of the topology.

02:24

So I'll start with a simple Insert

02:28

and then to add edges across here, I can now use the Cut tool

02:33

and so Cut works on CVs and edges.

02:37

And when Both is set, then I can use the Ctrl key for point snap on a vertex,

02:42

but just click and drag for an edge.

02:46

And I could use this Offset parameter if I want a particular value.

02:49

But more typically we just click and drag by eye

02:53

and that will give me these new edges

02:57

and I don't want a triangle

02:58

so I can cut again from this point to this edge.

03:03

And then I can just pick this edge,

03:05

not this one

03:06

and hit Delete on the keyboard to get back to a quad.

03:11

And then I can adjust the shape a bit if I want to.

03:15

But now I've got a five sided face here

03:18

so I can use Cut again, and I've got a choice of how to work.

03:22

I can either click on each edge to get the flow that I want

03:27

or if I undo that

03:29

I can also just get into a view where for example, this edge is lined up

03:34

and then just click all the way across

03:36

to create a cut that gives me a good layout.

03:42

So all that work reorganizing the topology now allows me to pick these edges.

03:48

And I'll just unpick those

03:51

and move them inwards to create a fully

03:53

controlled light catching feature along the bottom edge.

04:01

And then finally, I could add an extra edge here using Insert,

04:06

but I can also use Cut in a different mode.

04:10

So when my first click is not on the geometry,

04:13

then the second creates this cut line which is actually viewport based.

04:17

So you can see that I can move the model around and get it lined up

04:21

or adjust that cut line

04:24

and then hit Cut Through.

04:26

And that adds the new edges which I can just pick and move to tidy up the shape.

04:34

So Weld and Cut allow you to change the flow of the topology

04:38

to develop the features that you want on your design.

Video transcript

00:03

To develop this bottom edge of the side panels,

00:06

the topology will have to reflect all of these different directions.

00:10

And for this, I can use the Cut

00:13

the Weld and Unweld and the Extract tools.

00:16

So I'll need an extra face down here, so I'll just use Extrude

00:21

and make sure that's set to Subdiv Edges.

00:24

And this will weld to the origin edge but not to the side here.

00:30

So I can do that manually using the Weld tool.

00:34

And To Target means that I pick one vertex or edge

00:38

and then ask it to move and join to this one.

00:41

Or if I undo that

00:44

To Midpoint finds the center position.

00:46

And so I can just drag-select the vertices to join them in the middle.

00:52

And to show you the Tolerance option first, I'm going to use Unweld.

00:56

So if I wanted to separate out this fender, for example,

00:60

I could pick this edge loop and then choose Unweld.

01:03

And you can see that it's now a separate SubD.

01:08

But if I undo just the move,

01:11

these are still separate subdivs with the vertices pretty much coincident

01:16

and certainly within this tolerance.

01:19

So when I box-select and let go,

01:22

only the close or coincidence CVs are welded.

01:28

Over here on the hood, I could use Unweld again,

01:31

but I can also just pick the faces and do Extract

01:35

with Keep original off.

01:37

Then it works just like a cut and paste for SubD faces.

01:42

And then at this frontage,

01:45

if this time I use Extract with Keep original on,

01:49

then it's the equivalent of a copy and paste

01:52

because the normal copy and paste tools don't work on subdiv faces,

01:56

so we use Extract instead.

01:58

And then I could use that to start some new geometry

02:02

which starts out with the same structure and shape as the hood.

02:06

So Weld and Extract work within the existing topology and edge flow.

02:11

But if I now go back to the body side

02:14

and just get this angle how I want it.

02:18

I'm wanting to create an indent feature here.

02:20

So I'm going to need to change the flow of the topology.

02:24

So I'll start with a simple Insert

02:28

and then to add edges across here, I can now use the Cut tool

02:33

and so Cut works on CVs and edges.

02:37

And when Both is set, then I can use the Ctrl key for point snap on a vertex,

02:42

but just click and drag for an edge.

02:46

And I could use this Offset parameter if I want a particular value.

02:49

But more typically we just click and drag by eye

02:53

and that will give me these new edges

02:57

and I don't want a triangle

02:58

so I can cut again from this point to this edge.

03:03

And then I can just pick this edge,

03:05

not this one

03:06

and hit Delete on the keyboard to get back to a quad.

03:11

And then I can adjust the shape a bit if I want to.

03:15

But now I've got a five sided face here

03:18

so I can use Cut again, and I've got a choice of how to work.

03:22

I can either click on each edge to get the flow that I want

03:27

or if I undo that

03:29

I can also just get into a view where for example, this edge is lined up

03:34

and then just click all the way across

03:36

to create a cut that gives me a good layout.

03:42

So all that work reorganizing the topology now allows me to pick these edges.

03:48

And I'll just unpick those

03:51

and move them inwards to create a fully

03:53

controlled light catching feature along the bottom edge.

04:01

And then finally, I could add an extra edge here using Insert,

04:06

but I can also use Cut in a different mode.

04:10

So when my first click is not on the geometry,

04:13

then the second creates this cut line which is actually viewport based.

04:17

So you can see that I can move the model around and get it lined up

04:21

or adjust that cut line

04:24

and then hit Cut Through.

04:26

And that adds the new edges which I can just pick and move to tidy up the shape.

04:34

So Weld and Cut allow you to change the flow of the topology

04:38

to develop the features that you want on your design.

Video quiz

Required for course completion

Since the normal copy and paste tools do not work on subD faces, which of the following is often used as the equivalent of a copy and paste operation?

(Select one)
Select an answer

1/1 questions left unanswered

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