From BlenderWiki

Edges Tools

Here we will see mainly some of the options in the Specials/Edge Specials and Mesh » Edges menus. There are many more advanced options for edges, that we will see later on.

Bevel

Loop Subdivide... (or Loopcut in Edge Specials)

Knife Subdivide...

Subdivide

Subdivide Multi

Subdivide Fractal

Subdivide Smooth

All these “subdivision” tools are described in details here.

Make Edge/Face

It will create an edge or some faces, depending on your selection. We have already discussed this tool in the editing basics page.

Mark Seam and Clear Seam

Seams are a way to create separations, “islands”, in UV maps. See the UVTexturing part for more details. These commands set or unset this flag for selected edges.

Mark Sharp and Clear Sharp

The Sharp flag is used by the EdgeSplit modifier, which is part of the smoothing technics. As seams, it is a property of edges, and these commands set or unset it for selected ones.

Adjust Bevel Weight

This edge property (a value between 0.0 and 1.0) is used by the Bevel modifier to control the bevel intensity of the edges. This command enters an interactive mode (a bit like transform tools), where by moving the mouse (or typing a value with the keyboard) you can set the (average) bevel weight of selected edges.

Crease SubSurf

This edge property (a value between 0.0 and 1.0) is used by the Subsurf modifier to control the sharpness of the edges in the subdivided mesh. This command enters an interactive mode (a bit like transform tools), where by moving the mouse (or typing a value with the keyboard) you can set the (average) crease value of selected edges.

Rotate Edge CW / Rotate Edge CCW

Description

Rotating an edge clockwise or counter-clockwise spins an edge between two faces around their vertices. This is very useful for restructuring a mesh’s topology. The tool can operate on one explicitly selected edge, or on two selected vertices or two selected faces that implicitly select an edge between them.

Examples

Selected edge rotated CW and CCW.

Be aware that sometimes, as shown in (Selected edge rotated CW and CCW), indicated with a “T”, that you could produce what appears to be “T” junctions/nodes by using this tool. However, Blender has created additional edges that prevent cracks in the mesh. You can test this by selecting the vertex at the “T” and moving it around while noting that there are two edges now instead of one long edge.

Adjacent selected faces.

To rotate an edge based on faces you must select two faces, (Adjacent selected faces), otherwise Blender notifies you with an error message, “ERROR: Select one edge or two adjacent faces”. Using either Rotate Edge CW or Rotate Edge CCW will produce exactly the same results as if you had selected the common edge shown in (Selected edge rotated CW and CCW.).

Edge Slide

Description

Edge Slide slides one or more edges along faces adjacent to the selected edge(s) with a few restrictions involving the selection of edges.

Options

• LMB confirms the tool, and RMB or Esc cancels.
• This tool has both a Percentage and Proportional mode, which is displayed in the 3D View header. The default one is Percentage, use P to switch between them. See examples below for details.
  • In Proportional mode, Wheel , or ← and → changes the selected edge for calculating a proportion. Unlike Percentage mode, Proportional mode treats the edge as having a start and end vertex with the start marked by an enlarged magenta marker. You can flip to the opposite vertex using F.
• Holding Ctrl or ⇧ Shift control the precision of the sliding. Ctrl snaps movement to 10% steps per move and ⇧ Shift snaps movement to 1% steps. The default is 5% steps per move.

Examples

Simple

Simple edge slide.

(Simple edge slide) is an example of sliding an edge along an extruded box. The selected edge is labeled “E” and the adjacent faces to that edge are “F1” and “F2”. In “Edge moving”, the edge is being slid along the edge drawn in green. “Moved” shows the results.

Sliding Modes

Edge Slide Example Grid.

In order to explain Proportional and Percentage modes we can use a very simple mesh laid out like a 2×9 grid, (Edge Slide Example Grid). The vertices at “A” and “D” have been moved in order to emphasize the difference between the two modes. The vertices at the level “C” and “B” remain unchanged. “E” is an area of interest when looking at Proportional mode.

We assume you added a intermediate edge loop in this grid, using one of the subdivide tools (Subdivide, Loop Subdivide, Knife, …), and have selected only this edge loop.

Percentage mode

Percentage header.

In Percentage mode the 3D window header changes to (Percentage header) showing a number between -1 and 1 with 0 representing 50% or midway between.

As you move the mouse the percentage changes and the edge loop line, drawn in yellow, moves as a percentage of the distance between the edge marked in green as shown in (25% between), (Mid-way) and (89% between).

25% between.

Mid-way.

89% between.

The yellow loop line is always the same percentage along edge of the crossing edge loops, regardless of the edges’ lengths. For example, in (Mid-way) the yellow loop line is exactly halfway between vertex “A” and “B” and it is also exactly halfway between vertex “C” and “D”. For (25% between) you can see that the yellow line loop is always 25% along each of the crossed edges.

Proportional mode

Proportional header.

Proportional edge sliding keeps (or changes) the shape of the selected edge loop the same as one of the edge loops surrounding it, rather than sliding a percentage along each perpendicular edge.

In Proportional mode the 3D window header changes to (Proportional header) showing the position along the length of the currently selected edge which is marked in green, from the vertex that as an enlarged magenta marker. Movement of the sliding edge loop is restricted to this length. As you move the mouse the length indicator in the header changes showing where along the length of the edge you are.

Vertex Marker.

Vertex Marker Opposite.

Moving the mouse moves the selected edge loop towards or away from the start vertex, but the loop line will only move as far as the length of the currently selected edge, conforming to the shape of one of the bounding edge loops.

Proportional Range.

(Proportional Range) shows an example of how the distance is restricted by the length of the current edge (“B”). Looking at (“A”), you can see that the line loop has moved the same distance. If the line only moves 0.2 units on the selected edge then the line only moves 0.2 units everywhere else in the face loop region. The portion of the line loop at “A” hasn’t gone all the way to the “bottom” because the selected edge is only 0.25 units in length. The line portion at “A” will not be able to move more than 0.25 units down because the range of movement is restricted to the length of the selected edge.

Proportional Range Flipped.

(Proportional Range Flipped) is another example where the start vertex has been flipped while using the same selected edge as compared to (Proportional Range). You can see that movement is still restricted to the length of the selected edge. The yellow edge loop line stays straight, conforming to the bottom bounding edge loop because selected loop is placed a constant distance from the bottom edge loop, along the crossed edges.

Limitations & Workarounds

Loop crosses.

Single edges.

Order loop.

There are restrictions on the type of edge selections that can be operated upon. Invalid selections are:

“Loop crosses itself”

This means that the tool could not find any suitable faces that were adjacent to the selected edge(s). (Loop crosses) is an example that shows this by selecting two edges that share the same face. A face cannot be adjacent to itself.

“Was not a single edge loop”

Most likely you have selected edges that don’t share the same edge loop. (Single edges) is an example where the selected edges are not in the same edge loop, which means they don’t have a common edge. You can minimize this error by always selecting edges end to end or in a “Chain”.

“Could not order loop”

This means the tool could not find an edge loop based on the selected edge(s). (Order loop) is an example where a single edge was selected in a 2D Plane object. An edge loop can not be found because there is only one face. Remember, edge loops are loops that span two or more faces.

A general rule of thumb is that if multiple edges are selected they should be connected end to end such that they form a continuous chain. This is literally a general rule because you can still select edges in a chain that are invalid because some of the edges in the chain are in different edge loops. (Loop crosses) is just such an example where the selected edges form a chain but they are not in the same edge loop.

If you select multiple edges just make sure they are connected. This will decrease the possibility of getting looping errors.

Delete Edge Loop

Description

Erase menu.

Delete Edge Loop allows you to delete a selected edge loop if it is between two other edge loops. This will create one face-loop where two previously existed.

Limitations & Workarounds

You can only delete one (part of) an edge loop at a time, else the tool will show you one of the error messages “loop crosses itself” or “Was not a single edge loop”. In general, the same restrictions as those of Edge Slide apply, see above for more details.

Examples

The selected edge loop on the UV Sphere has been deleted and the faces have been merged with the surrounding edges. If the edges had been deleted by choosing Edges from the (Erase Menu) there would be an empty band of deleted faces all the way around the sphere instead.

Before Delete Edge Loop.

After Delete Edge Loop.

Collapse

This options is the same as the one described in the Merge menu (don’t know why it is here…).