From BlenderWiki

Jump to: navigation, search
Tutorial Note
I know that this isn't really a tutorial per se, but i figured i do not want to disrupt the work that is done on the manual (see BSoD) with additional text. I believe this should be included into the manual or the reference somewhere later on though.


What do I need to auto-fill

When working with geometry in Blender you sometimes are in the situation where you want to fill a hole or empty area with faces. This does not always work, and if it works it has different results depending on the method you use.

Note
I'll call the vertices/edges around the 'empty' area "ring" inside this tutorial.


Doesn't work

Tutorial-fill-faces-01.png

The first thing you need to check is if the ring you want to fill is complete. i.e.: the ring is closed. Otherwise the filling with faces will not work later on.

The image shows such an 'open' ring/area ... a classic "C-shape".

Fixing the problem

To close the ring you do the following:

  • Optional: make sure you are in Vertex select mode by pressing Ctrl⇆ Tab -> Vertices
  • Select the two ends of the ring (Hold ⇧ Shift + click 2x RMB Template-RMB.png on the vertices)
  • Hit F (or Space -> Edit -> Edges -> Make Edge/Face) to create the closing edge.
Tutorial-fill-faces-02.png


Filling the ring

In Blender there are several ways to fill a ring with faces. But currently they all start with the #Basic fill below.

Basic fill

To fill a ring with faces you do the following:

  • Select (RMB Template-RMB.png) the ring in either Vertex or Edge selection mode (Ctrl⇆ Tab again)
  • Press ⇧ ShiftF
  • Now the ring will be filled with triangles.
Tutorial-fill-faces-03.png


Convert to beauty fill

There is a command called Beauty Fill to convert existing faces (in this case the generated triangles of the #Basic fill method) into a pattern that is sometimes 'cleaner'.

  • Select the faces you want to convert
  • Press AltF
Tutorial-fill-faces-04.png
Note
It doesn't matter where the faces come from that you want to convert. e.g.: You can fill a ring, then make it a beauty fill or you can also select some random faces on a mesh and do this.


Convert to quads

Another useful command to 'clean' faces is the one to convert them to quads (4-sided faces).

  • Select the faces you want to convert
  • Press AltJ
Tutorial-fill-faces-05.png
Note
And again it doesn't matter where the faces come from that you want to convert. e.g.: You can fill a ring, then make it a beauty fill and finally convert them to quads or you can also select some random faces on a mesh and do this.


The Extrude-scale-merge way

There is one more way to fill the ring, but it can't be used on every occasion:

  • You can't use smooth subdivision or a SubSurf modifier afterwards in most cases.
  • The ring can't have specific shapes (like a double-T shape ... that's because there is a single vertex created in the middle (by scaling to zero) that will most likely force some edges to cross the outer boundary.

Step by step:

  • Select the ring
  • Extrude edges E -> Only Edges (Extrude the ring.)
  • Scale to 0 (S, 0, ↵ Enter)
  • W -> Remove Doubles (Remove Doubles.)
Extrude the ring.
Remove Doubles.
Subsurf tip
You can make this way SubSurf-able if you extrude the edges, but don't scale to 0, but to something bigger, then extrude again, scale to 0 and merge. this will subsurf a lot better not. Tutorial-fill faces-extrude 03.png


Single faces

Sometimes you want to define for yourself where some of the faces should go. There are several commands that will help you with that.

Create single face

This is one of the most-needed function for face-creation.

  • Select two edges or 3-4 vertices (RMB Template-RMB.png again)
  • Press F
Tutorial-fill-faces-06.png
Note
Some faces can't be created because they would make a concave polygon/face. Read more about that in
Introduction to Character Animation: Concave quads


Cleanup after creation

If you create faces one by one sometimes Blender doesn't know where to put the 'outside' (i.e. the Normal) of the face. This will result in strange gradient changes and/or color streaks/lines all over the mesh.

Normally the best way to solve this is to

  • Select all geometry with A
  • Press CtrlN to Recalculate normals outside (or Space -> Edit -> Normals -> Recalculate Outside)
Tutorial-fill-faces-07.png


In case of strange gradient it may also be helpful to check the set smooth/set solid option.

TODO: Bridge/Loft

Mode: Edit Mode (Mesh)

Menu: Mesh → Scripts → Bridge Faces/Edge-Loops

There is a script that can bridge/loft faces or edges in blender. It is located in the menu MeshScriptsBridge Faces/Edge-Loops in Edit Mode (⇆ Tab on a mesh object).

See also Scripts/Catalog/Mesh#mesh skin.

TODO: Write nice tutorial to show what it can do.

Select two face-regions (or edgeloops) an run execute the bridge command.

TODO: N-Gons