Edit mesh: points, edges and polygons

Until now a click in the 3D view picked a whole part. Edit mesh lets you into the part. You pick its points, its edges or its polygons, and you can move them, take them out, join them or close a hole. If you have used Cinema 4D, it works the same way.

A mesh is made of three kinds of piece. A point is a corner (the glossary calls it a vertex). An edge is the line between two points. A polygon is a flat face. Two triangles that together make a four-sided shape count as one polygon, as a cell of a grid or a strip of a tube wall does. A triangle with no such partner is a polygon of its own. See Words you will meet.

Go in and out

The mode button is at the top of the tool strip on the left edge of the view. It offers four modes: Points, Edges, Polygons and Model. Model is the app as it always was: a click picks a part.

1

Points

2

Edges

3

Polygons

4

Model: leave Edit mesh

• Click the button once to go into the last piece mode you used, or back out again.
• Hold the button to see the list of all four.
• While Edit mesh is on, three more buttons appear under the mode button: Points, Edges and Polygons. The lit one is the kind of piece you are picking, and a click on another switches to it. The mode button itself shows the Model icon then, and a click on it goes back to Model.
• The view modes (solid, wireframe, X-ray, heatmap) that these keys used to switch are now on Alt1 to Alt4. See View modes.

What you see

• The selected parts show their mesh lines in blue, as polygons rather than triangles.
• The pieces you have picked are orange. The one under the pointer is light.
• In Points mode every point of the part is shown.

Pick pieces

The Edit mesh tools are a bar at the right edge of the view, under the view cube. It replaces the card that earlier versions had. At the top of the bar are three tools that decide how the left mouse button picks. With all three, Shift adds to what is picked and Ctrl takes away from it.

Click

One piece at a time. A click beside the model clears the pick. A double-click picks a loop. With Click, a point is taken only when the pointer is within 16 pixels of it, and an edge within 12 pixels.

Box

Drag a rectangle. What lies in it whole, and can be seen, is picked. The pick is live: it follows the box while you drag, and pieces the box lets go of are let go. The gizmo is put away during the drag. The history gets one entry when you let go. If you change tool, or the pointer is lost, in the middle of a drag, the box is cancelled and what you had picked comes back.

Brush

Paint over the model. What the brush passes over is picked. Hold the middle button and drag to change the size of the brush, or type it in the bar.

With Box and Brush, Alt and drag turns the view. Loops in the bar does what a double-click does for every click, and lights the loop under the pointer before you click.

A loop of polygons runs across four-sided polygons like a ring round a tube. Where the polygons are not four-sided, the loop is the whole face. A loop of edges is the outline of a face when the edge is sharp or open, and the row of edges when it is smooth.

CtrlA

Pick everything of the selected parts

CtrlZ

Take back the last change of what is picked

Move, turn and scale

The gizmo sits in the middle of what is picked. E moves, R turns and T scales, and Shift snaps, as for a whole part (see Move, rotate, scale). It moves the points the pieces stand on, so everything that uses those points follows.

The bar also sets the gizmo’s axes: World, Local or Normal. With Normal the gizmo’s Z points along the average normal of the picked pieces, so a polygon can be pulled straight out of itself.

Letting go of the gizmo is one undo step, and the pieces stay picked. Clicking a handle without dragging adds nothing to the history. In the wireframe view the part keeps one set of lines while its pieces are worked on, and they follow the move.

Delete and reverse

• Del takes the picked pieces out. A point or an edge takes every polygon that uses it. A part is never emptied this way. The polygons of what stays are kept.
• Reverse normals turns the picked polygons round, so their front becomes their back. Use it for faces that came in the wrong way, which look dark or see-through from one side.

The tools that change the mesh

Each one is a button in the bar, below the gizmo’s axes, and each is one undo step. A button works on one kind of piece and is dimmed when something else is picked.

Dissolve

With CtrlBackspace. Picked points are taken out and the surface closes over them. For picked edges and polygons the polygons become one, and the points left inside them, or on a straight line of their outline, go. The shape does not change there.

Planarize

For polygons. Moves the points of each picked polygon onto its best-fit plane. A polygon that would have to bend a long way, such as a curved face, is left as it is.

Straighten

For edges. Moves the points along a picked line of edges onto the straight line between its two ends.

Weld

For points and edges. Opens a small card of its own, with Join within and a Weld button. Picked points become one, at their middle. With a distance in Join within, the points that are that close to each other become one each. With 0, all the picked points become one. Picked edges collapse to a point. Triangles that are left with two corners in one place go.

Fill

For edges. Closes a hole whose whole rim is picked. A double-click on an open edge picks the whole loop. The cap has points of its own, so it shades on its own.

Extract

For polygons. Takes the picked polygons out into a part of their own, in the same place and with the same material.

Reverse normals

For polygons. Described above.

Key tips

While Edit mesh is on, the faint list of tips at the bottom right of the view shows what the mouse and keys do right now. It follows the tool you hold and what is picked. With nothing picked it tells you how to pick, and that CtrlA picks all and Esc goes back to Model. With something picked it adds Del to delete, CtrlBackspace to dissolve and Esc to let go.

Good to know

• The quads and n-gons of an OBJ or FBX file are remembered after the file is read, so the polygons of the file are known afterwards.
• Quick remesh does not run while Edit mesh is on. Go back to Model first.
• Leaving Edit mesh in the middle of a drag finishes the move as one undo step.
• Everything here is one undo step, and after an undo the pieces are picked again. See Undo and redo.