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index.rst.txt

@@ -1,13 +1,18 @@
+.. _bpy.types.Mesh:
+.. _bpy.ops.mesh:
 
-###########
-  Editing
-###########
+##########
+  Meshes
+##########
 
 .. toctree::
    :maxdepth: 2
 
-   transform_panel.rst
-   surface.rst
-   control_points.rst
-   segments.rst
-   other.rst
+   introduction.rst
+   toolbar/index.rst
+   structure.rst
+   primitives.rst
+   selecting.rst
+   editing/index.rst
+   properties/index.rst
+   mesh_analysis.rst

introduction.rst.txt

@@ -3,45 +3,25 @@
 Introduction
 ************
 
-Curves are 2D objects, and surfaces are their 3D extension.
-Note however, that in Blender, you only have NURBS surfaces,
-no Bézier (you have the *Bézier* knot type, though; see below),
-nor polygonal (but for these, you have meshes!).
-Even though curves and surfaces share the same object type (with texts also...),
-they are not the same thing; for example,
-you cannot have in the same object both curves and surfaces.
+Mesh Modeling typically begins with
+a :doc:`Mesh Primitive </modeling/meshes/primitives>` shape (e.g. circle, cube, cylinder...).
+From there you might begin editing to create a larger, more complex shape.
 
-.. _fig-surface-intro-surface:
 
-.. figure:: /images/modeling_surfaces_introduction_nurbs-surface.png
+Modeling Modes
+==============
 
-   NURBS surface in Edit Mode.
+The 3D View has three principal modes that allow for the creation,
+editing and manipulation of the mesh models.
+Each of the three modes have a variety of tools. Some tools may be found in one or more of the modes.
 
-As surfaces are 2D, they have two interpolation axes, U (as for curves) and V.
-It is important to understand that you can control the interpolation rules (knot, order, resolution)
-*independently* for each of these two dimensions
-(the U and V fields for all these settings, of course).
+Modes that used for modeling:
 
-You may ask yourself "but the surface appears to be 3D, why is it only 2D?".
-In order to be 3D, the object needs to have "Volume", and a surface, even when it is closed,
-does not have volume; it is infinitely thin.
-If it had a volume the surface would have a thickness (its third dimension). Hence,
-it is only a 2D object, and has only two interpolation dimensions or axes or coordinates
-(if you know a bit of math, think of non-Euclidean geometry -- well,
-surfaces are just non-Euclidean 2D planes...). To take a more "real-world" example,
-you can roll a sheet of paper to create a cylinder; well, even if it becomes a "volume",
-the sheet itself will remain a (nearly...) 2D object!
-
-In fact, surfaces are very similar to the results you get when
-:doc:`extruding a curve </modeling/curves/properties/geometry>`.
-
-
-Visualization
-=============
-
-There is nearly no difference from NURBS curves,
-except that the U direction is indicated by yellow grid lines,
-and the V one is materialized by pink grid lines, as you can see in
-Fig. :ref:`fig-surface-intro-surface`.
-
-You can :ref:`hide and reveal <curves-show-hide>` control points just as with curves.
+Object Mode
+   Supports basic operations such as object creation,
+   joining objects, managing shape keys, UV/color layers.
+Edit Mode
+   Used for the majority of mesh editing operations.
+Sculpt Mode
+   Instead of dealing with individual mesh elements,
+   support sculpting with brushes *(not covered in this chapter)*.

mesh_analysis.rst.txt

@@ -0,0 +1,115 @@
+.. _bpy.types.MeshStatVis:
+.. _modeling-mesh-analysis:
+
+*************
+Mesh Analysis
+*************
+
+.. admonition:: Reference
+   :class: refbox
+
+   :Mode:      Edit Mode
+   :Panel:     :menuselection:`Header --> Overlays --> Mesh Analysis`
+
+Mesh analysis is useful for displaying attributes of the mesh,
+that may impact certain use cases.
+
+The mesh analysis works in *Edit Mode* and *Solid* Viewport shading.
+It shows areas with a high value in red, and areas with a low value in blue.
+Geometry outside the range is displayed gray.
+
+Currently the different modes target 3D printing as their primary use.
+
+
+Overhang
+========
+
+Extrusion 3D printers have a physical limit to the overhang that can be printed,
+this display mode shows the overhang with angle range and axis selection.
+
+Minimum/Maximum
+   Minimum/Maximum angle to display.
+Axis
+   Axis and direction to use as the bases to calculate the angle to visualize.
+
+.. figure:: /images/modeling_meshes_mesh-analysis_overhang.png
+   :width: 350px
+   :align: center
+
+   Overhang.
+
+
+Thickness
+=========
+
+Printers have a limited *wall-thickness* where very thin areas cannot be printed,
+this test uses ray casting and a distance range to the thickness of the geometry.
+
+Minimum/Maximum
+   Minimum/Maximum thickness to display.
+Samples
+   Number of samples to use to calculate the thickness.
+
+.. figure:: /images/modeling_meshes_mesh-analysis_thickness.png
+   :width: 400px
+   :align: center
+
+   Thickness.
+
+
+Intersections
+=============
+
+Another common cause of problems for printing are intersections between surfaces,
+where the inside/outside of a model cannot be reliably detected.
+
+Unlike other display modes, intersections have no variance and are either on or off.
+
+.. figure:: /images/modeling_meshes_mesh-analysis_intersections.png
+   :width: 400px
+   :align: center
+
+   Intersecting faces.
+
+
+Distortion
+==========
+
+Distorted geometry can cause problems since the triangulation of a distorted n-gon is undefined.
+
+Distortion is measured by faces which are not flat,
+with parts of the face pointing in different directions.
+
+Minimum/Maximum
+   Minimum/Maximum distortion to display.
+
+
+.. figure:: /images/modeling_meshes_mesh-analysis_distortion.png
+   :width: 300px
+   :align: center
+
+   Distorted Faces.
+
+
+Sharp Edges
+===========
+
+Similar to wall-thickness, sharp edges can form shapes that are too thin to be able to print.
+
+Minimum/Maximum
+   Minimum/Maximum angle to display.
+
+.. figure:: /images/modeling_meshes_mesh-analysis_sharp-edges.png
+   :width: 350px
+   :align: center
+
+   Sharp edges.
+
+
+Known Limitations
+=================
+
+There are some known limitations with mesh analysis:
+
+- Currently only displayed with Deform Modifiers.
+- For high-poly meshes the performance is low while editing.

primitives.rst.txt

@@ -1,4 +1,4 @@
-.. _bpy.ops.surface.primitive*add:
+.. _bpy.ops.mesh.primitive*add:
 
 **********
 Primitives
@@ -8,63 +8,211 @@ Primitives
    :class: refbox
 
    :Mode:      Object Mode and Edit Mode
-   :Menu:      :menuselection:`Add --> Curve`
+   :Menu:      :menuselection:`Add --> Mesh`
    :Hotkey:    :kbd:`Shift-A`
 
-.. seealso::
+A common object type used in a 3D scene is a mesh.
+Blender comes with a number of "primitive" mesh shapes that you can start modeling from.
+You can also add primitives in Edit Mode at the 3D cursor.
 
-   When adding curves there are some common options like other :ref:`Objects <object-common-options>`.
+.. figure:: /images/modeling_meshes_primitives_all.png
 
-In Object/Edit Mode, the *Add Surface* menu, provides six different surface primitives:
+   Blender's standard primitives.
 
-.. list-table::
+.. note:: Planar Primitives
 
-   * - .. figure:: /images/modeling_surfaces_primitives_surface.png
+   You can make a planar mesh three-dimensional by moving one or more of the vertices out of its plane
+   (applies to *Plane*, *Circle* and *Grid*).
+   A simple circle is often used as a starting point to create even the most complex of meshes.
 
-          NURBS surface primitives.
 
-     - .. figure:: /images/modeling_surfaces_primitives_curve.png
+Common Options
+==============
 
-          NURBS curve primitives.
+These options can be specified in the :ref:`ui-undo-redo-adjust-last-operation` panel,
+which appears when the object is created.
+Options included in more than one primitive are:
 
+Generate UVs
+   Generates a default UV unwrapping of new geometry.
+   This will be defined in the first UV layer (which will get added if needed).
+Radius/Size, Align to View, Location, Rotation
+   See :ref:`Common Object Options <object-common-options>`.
 
-NURBS Curve
-===========
 
-*NURBS Curve* only have one control point on each V row.
+Plane
+=====
 
-TODO.
+The standard plane is a single quad face, which is composed of four vertices, four edges, and one face.
+It is like a piece of paper lying on a table;
+it is not a three-dimensional object because it is flat and has no thickness.
+Objects that can be created with planes include floors, tabletops, or mirrors.
 
 
-NURBS Circle
-============
+Cube
+====
 
-*NURBS Circle* only have one control point on each V row.
+A standard cube contains eight vertices, twelve edges, and six faces,
+and is a three-dimensional object. Objects that can be created out of cubes include dice,
+boxes, or crates.
 
-TODO.
 
-Note how a circle :term:`NURBS` surface is never filled, unlike its "real" curve counterpart...
+Circle
+======
 
+Vertices
+   The number of vertices that define the circle or polygon.
+Fill Type
+   Set how the circle will be filled.
 
-NURBS Surface
-=============
+   Triangle Fan
+      Fill with triangular faces which share a vertex in the middle.
+   N-gon
+      Fill with a single :term:`n-gon`.
+   Nothing
+      Do not fill. Creates only the outer ring of vertices.
 
-TODO.
 
+UV Sphere
+=========
 
-NURBS Cylinder
-==============
+A standard UV sphere is made out of quad faces and a triangle fan at the top and bottom.
+It can be used for texturing.
+
+Segments
+   Number of vertical segments. Like the Earth's meridians, going pole to pole.
+Rings
+   Number of horizontal segments. These are like the Earth's parallels.
+
+   .. note::
+
+      Rings are face loops and not edge loops, which would be one less.
+
+
+Icosphere
+=========
+
+An icosphere is a polyhedral sphere made up of triangles.
+Icospheres are normally used to achieve a more isotropical layout of
+vertices than a UV sphere, in other words, they are uniform in every direction.
+
+Subdivisions
+   How many recursions are used to define the sphere.
+   At level 1 the icosphere is an icosahedron, a solid with 20 equilateral triangular faces.
+   Each increase in the number of subdivisions splits each triangular face into four triangles.
+
+.. note::
+
+   Subdividing an icosphere raises the vertex count very quickly even with few iterations
+   (10 times creates 5,242,880 triangles),
+   Adding such a dense mesh is a sure way to cause the program to crash.
+
+
+Cylinder
+========
+
+Objects that can be created out of cylinders include handles or rods.
+
+Vertices
+   The number of vertical edges between the circles used to define the cylinder or prism.
+Depth
+   Sets the starting height of the cylinder.
+
+Cap Fill Type
+   Similar to circle (see above). When set to none, the created object will be a tube.
+   Objects that can be created out of tubes include pipes or drinking glasses
+   (the basic difference between a cylinder and a tube is that the former has closed ends).
+
+
+Cone
+====
+
+Objects that can be created out of cones include spikes or pointed hats.
+
+Vertices
+   The number of vertical edges between the circles or tip, used to define the cone or pyramid.
+Radius 1
+   Sets the radius of the circular base of the cone.
+Radius 2
+   Sets the radius of the tip of the cone. which will create a frustum (a pyramid or cone with the top cut off).
+   A value of 0 will produce a standard cone shape.
+Depth
+   Sets the starting height of the cone.
+
+Base Fill Type
+   Similar to circle (see above).
+
+
+Torus
+=====
+
+A doughnut-shaped primitive created by rotating a circle around an axis.
+The overall dimensions can be defined by two methods.
+
+Operator Presets
+   Torus preset settings for reuse. These presets are stored as scripts in the proper presets directory.
+Major Segments
+   Number of segments for the main ring of the torus.
+   If you think of a torus as a "spin" operation around an axis, this is how many steps are in the spin.
+Minor segments
+   Number of segments for the minor ring of the torus.
+   This is the number of vertices of each circular segment.
+
+
+Torus Dimensions
+----------------
+
+Add Mode
+   Change the way the torus is defined.
+
+   Major/Minor, Exterior/Interior
+
+   Major Radius
+      Radius from the origin to the center of the cross sections.
+   Minor Radius
+      Radius of the torus' cross section.
+
+   Exterior Radius
+      If viewed along the major axis,
+      this is the radius from the center to the outer edge.
+   Interior Radius
+      If viewed along the major axis,
+      this is the radius of the hole in the center.
+
+
+Grid
+====
+
+A regular quadratic grid which is a subdivided plane.
+Example objects that can be created out of grids include landscapes
+and organic surfaces.
+
+X Subdivisions
+   The number of spans in the X axis.
+Y Subdivisions
+   The number of spans in the Y axis.
+
+
+Monkey
+======
 
-TODO.
+This adds a stylized monkey head to use as a test mesh,
+use :term:`Subdivision Surface` for a refined shape.
 
+This is intended as a test mesh, similar to:
 
-NURBS Sphere
-============
+- `Utah Teapot <https://en.wikipedia.org/wiki/Utah_teapot>`__
+- `Stanford Bunny <https://en.wikipedia.org/wiki/Stanford_Bunny>`__.
 
-TODO.
+.. hint:: History
 
+   This is a gift from old NaN to the community and is seen as a programmer's joke or
+   "Easter Egg". It creates a monkey's head once you press the *Monkey* button.
+   The Monkey's name is "Suzanne" and is Blender's mascot.
 
-NURBS Torus
-===========
+.. note:: Add-ons
 
-TODO.
+   In addition to the basic geometric primitives,
+   Blender has a number of script generated meshes to offer as pre-installed add-ons.
+   These are available when enabled in the :doc:`Preferences </editors/preferences/addons>`
+   (select the Category *Add Mesh*, then check any desired items).

selecting.rst.txt

@@ -3,33 +3,176 @@
 Selecting
 *********
 
-This page discusses specific selecting tools for surface objects in Edit Mode.
-The Surface Edit more also uses the general select tools used which are described
-in the :doc:`interface section </interface/selecting>`.
+There are many ways to select elements, and it depends on what *Mesh Select Mode*
+you are in as to what selection tools are available.
+First we will go through these modes and after that a look is taken at basic selection tools.
 
-Surface selection in *Edit Mode* is very similar to
-:doc:`NURBS curve selection </modeling/curves/selecting>`.
-The basic tools are the same as with :doc:`meshes </modeling/meshes/selecting>`,
-so you can select a simple control point with an :kbd:`LMB`\ -click,
-add to current selection with :kbd:`Shift-LMB` clicks, :kbd:`B` order-select, and so on.
 
+Selection Modes
+===============
 
-Select Menu
-===========
+Select Mode Header Buttons
+--------------------------
+
+.. admonition:: Reference
+   :class: refbox
+
+   :Mode:      Edit Mode
+   :Menu:      :menuselection:`3D View Header --> Select Mode`
+   :Hotkey:    :kbd:`1`, :kbd:`2`, :kbd:`3`
+               (:kbd:`Shift`
+               `Multiple Selection Modes`_,
+               :kbd:`Ctrl` `Expand/Contract Selection`_).
+
+.. figure:: /images/modeling_meshes_selecting_mode-buttons.png
+   :align: right
+   :width: 200px
+
+   Edit Mode selection buttons.
+
+In *Edit Mode* there are three different selection modes.
+You can enter the different modes by selecting one of the three buttons in the header.
+
+Vertices
+   In this mode vertices are shown as points.
+
+   Selected vertices are displayed in orange, unselected vertices in black,
+   and the active or last selected vertex in white.
+Edges
+   In this mode the vertices are not shown.
+
+   Instead the selected edges are displayed in orange,
+   unselected edges black, and the active or last selected edge in white.
+Faces
+   In this mode the faces are displayed with a selection point in the middle which is used for selecting a face.
+
+   Selected faces and their selection point are displayed in orange,
+   unselected faces are displayed in black, and the active or last selected face is highlighted in white.
+
+When using these buttons, you can make use of modifier keys, see: `Switching Select Mode`_.
+
+Almost all tools are available in all three mesh selection modes.
+So you can *Rotate*, *Scale*, *Extrude*, etc. in all modes.
+Of course rotating and scaling a *single* vertex will not do anything useful
+(*without* setting the pivot point to another location),
+so some tools are more or less applicable in some modes.
+
+See Fig. :ref:`fig-mesh-select-intro-selection-modes` for examples of the different modes.
+
+
+Multiple Selection Modes
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+By holding :kbd:`Shift-LMB` when selecting a selection mode,
+you can enable multiple *Selection Modes* at once.
+This allows you to quickly select Vertices/Edges/Faces,
+without first having to switch modes.
+
+.. _fig-mesh-select-intro-selection-modes:
+
+.. list-table:: Selection modes.
+
+   * - .. figure:: /images/modeling_meshes_selecting_vertex-mode-example.png
+          :width: 310px
+
+          Vertex mode example.
+
+     - .. figure:: /images/modeling_meshes_selecting_edge-mode-example.png
+          :width: 310px
+
+          Edge mode example.
+
+   * - .. figure:: /images/modeling_meshes_selecting_face-mode-example.png
+          :width: 310px
+
+          Face mode example.
+
+     - .. figure:: /images/modeling_meshes_selecting_mixed-mode-example.png
+          :width: 310px
+
+          Mixed mode example.
+
+
+Switching Select Mode
+---------------------
+
+When switching modes in an "ascendant" way (i.e. from simpler to more complex), from
+*Vertices* to *Edges* and from *Edges* to *Faces*,
+the selected parts will still be selected if they form a complete element in the new mode.
+
+For example, if all four edges in a face are selected,
+switching from *Edges* mode to *Faces* mode will keep the face selected.
+All selected parts that do not form a complete set in the new mode will be unselected.
+
+.. list-table::
+
+   * - .. figure:: /images/modeling_meshes_selecting_edge-mode-example.png
+          :width: 310px
+
+          Edge mode, the initial selection.
+
+     - .. figure:: /images/modeling_meshes_selecting_face-mode-switched-from-edge.png
+          :width: 310px
+
+          Switching to Face mode.
+
+Hence, switching in a "descendant" way (i.e. from more complex to simpler),
+all elements defining the "high-level" element (like a face) will be selected
+(the four vertices or edges of a quadrangle, for example).
 
-The *Select* menu (in the 3D Viewport header) is even simpler than for curves...
 
-All these options have the same meaning and behavior as in
-:doc:`Object Mode </scene_layout/object/selecting>`
-(and the specificities of *Box Select* in *Edit Mode* have already been discussed
-:doc:`here </modeling/meshes/selecting>`).
+Expand/Contract Selection
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+By holding :kbd:`Ctrl` when selecting a higher selection mode,
+all elements touching the current selection will be added,
+even if the selection does not form a complete higher element.
+
+Or contracting the selection when switching to a lower mode.
+
+.. list-table::
+
+   * - .. figure:: /images/modeling_meshes_selecting_vertex-mode-example.png
+          :width: 310px
+
+          Vertex mode, the initial selection.
+
+     - .. figure:: /images/modeling_meshes_selecting_edge-mode-expanding-from-vertex.png
+          :width: 310px
+
+          Expanding to Edge mode.
+
+
+X-Ray
+=====
+
+The :ref:`x-ray <3dview-shading-xray>` setting is not just for shading, it impacts selection too.
+
+When enabled, selection isn't occluded by the objects geometry
+(as if the object was solid).
+
+.. list-table::
+
+   * - .. figure:: /images/modeling_meshes_selecting_limit-selection-to-visible-off.png
+          :width: 310px
+
+          X-ray enabled.
+
+     - .. figure:: /images/modeling_meshes_selecting_limit-selection-to-visible-on.png
+          :width: 310px
+
+          X-ray disabled.
+
+
+Select Menu
+===========
 
 All :kbd:`A`
    Select all.
 None :kbd:`Alt-A`
    Select none.
 Inverse :kbd:`Ctrl-I`
-   Selects all the geometry that are not selected, and deselect currently selected components.
+   Selects all the geometry that is not selected, and deselect currently selected components.
 
 ------------------------
 
@@ -40,50 +183,78 @@ Inverse :kbd:`Ctrl-I`
 
 ------------------------
 
-`Select Random`_
-   Select random control points.
+Select Random
+   Selects a random group of vertices, edges, or faces, based on a percentage value.
+:ref:`Checker Deselect <modeling-selecting-checker_deselect>`
+   De-select alternate elements relative to the active item.
 
-`Checker Deselect`_
-   Select every Nth control point.
+------------------------
 
-`Select Linked`_ :kbd:`Ctrl-L`
-   Select control points that are connected to the current selection.
+Select Sharp Edges
+   This tool selects all edges between two faces forming an angle greater than the angle value,
+   Where an increasing angle selects sharper edges.
+
+------------------------
 
 `Select Similar`_ :kbd:`Shift-G`
-   Select control points that have similar properties to the current selection.
+   Select elements similar to the current selection.
 
 ------------------------
 
-`Select Control Point Row`_
-   Select a whole :ref:`row <modeling-surfaces-rows-grids>` of control points.
+`Select All by Trait`_
+   Select geometry by querying it's characteristics.
 
 ------------------------
 
-`Select More/Less`_
-   Select objects based on their parent child relationships.
+Select More/Less
+   More :kbd:`Ctrl-NumpadPlus`
+      Expands the selection to the adjacent elements of the selection type.
+   Less :kbd:`Ctrl-NumpadMinus`
+      Contracts the selection from the adjacent elements of the selection type.
+   Next Active :kbd:`Shift-Ctrl-NumpadPlus`
+      This uses selection history to select the next vertex/edge/face based on surrounding topology.
+   Previous Active :kbd:`Shift-Ctrl-NumpadMinus`
+      Select previous just removes the last selected element.
 
+------------------------
 
-Select Random
-=============
+Select Loops
+   `Edge Loops`_
+      Select connected edges.
+   `Face Loops`_
+      Select connected faces.
+   `Edge Boundary`_
+      Select boundary edges.
+   `Edge Ring`_
+      Select connected edge ring.
 
-.. admonition:: Reference
-   :class: refbox
+------------------------
 
-   :Mode:      Edit Mode
-   :Menu:      :menuselection:`Select --> Select Random`
+Select Linked
+   `Select Linked`_
+      Selects all components that are connected to the current selection (see `Select Linked`_).
+   `Shortest Path`_
+      Path between two selected elements.
+   Linked Flat Faces
+      Select connected faces based on a threshold of the angle between them.
+      This is useful for selecting faces that are planar.
+
+------------------------
+
+Select Side of Active
+   Selects all vertices on the mesh in a single axis relative to the active vertex.
+   In Vertex selection mode only.
+Mirror Selection :kbd:`Shift-Ctrl-M`
+   Select mesh items at the mirrored location across the chosen axis.
 
-Select random control points.
 
-Percent
-   Selects the defined percentage of control points.
-Random Seed
-   :term:`Seed` used by the pseudo-random number generator.
-Action
-   Controls whether the operator *Selects* or *Deselects* control points.
+Selection Tools
+===============
 
+.. _modeling-selecting-checker_deselect:
 
 Checker Deselect
-================
+----------------
 
 .. admonition:: Reference
    :class: refbox
@@ -92,10 +263,14 @@ Checker Deselect
    :Menu:      :menuselection:`Select --> Checker Deselect`
 
 This tool applies an alternating selected/deselected checker pattern.
-This only works if you already have more than one control point selected.
+This only works if you already have more than one mesh element selected.
 
-It works by changing the current selection so that only every Nth
-control points will remain selected, starting from the active one.
+Changes the current selection so that only every Nth elements (vertices, edges or faces,
+depending on the active selection mode) will remain selected, starting from the active one.
+
+In case of islands of selected elements, this tool will affect
+only the island of the active element (if there is one), or the island of the first element
+in the order of internal storage (if there is no active element).
 
 Nth Selection
    Skip every Nth element leaving it selected.
@@ -105,92 +280,361 @@ Offset
    Offset from the starting point.
 
 
+Select All by Trait
+-------------------
+
+.. _mesh-select-non-manifold:
+
+Non Manifold
+   Selects the :term:`non-manifold` geometry of a mesh.
+   This entry is available when editing a mesh, in Vertex and Edge selection modes only.
+
+   Extend
+      Lets you extend the current selection.
+   Wire
+      Selects all the edges that do not belong to any face.
+   Boundaries
+      Selects edges in boundaries and holes.
+   Multiple Faces
+      Selects edges that belong to three or more faces.
+   Non Contiguous
+      Selects edges that belong to exactly two faces with opposite normals.
+   Vertices
+      Selects vertices that belong to *wire* and *multiple face* edges, isolated vertices,
+      and vertices that belong to non-adjoining faces.
+
+Loose Geometry
+   Selects all vertices or edges that do not form part of a face.
+Interior Faces
+   Selects faces where all edges have more than two faces.
+Faces by Sides
+   Selects all faces that have a specified number of edges.
+
+------------------------
+
+Ungrouped Vertices
+   Selects all vertices which are not part of
+   a :doc:`vertex group </modeling/meshes/properties/vertex_groups/index>`.
+
+
 Select Linked
-=============
+-------------
 
 .. admonition:: Reference
    :class: refbox
 
    :Mode:      Edit Mode
-   :Menu:      :menuselection:`Select --> Select Linked`
-   :Hotkey:    :kbd:`L`, :kbd:`Ctrl-L`
+   :Menu:      :menuselection:`Select --> Linked`
+   :Hotkey:    :kbd:`Ctrl-L`
+
+Select geometry connected to already selected elements.
+This is often useful when a mesh has disconnected, overlapping parts,
+where isolating it any other way would be tedious.
+
+To give more control, you can also enable delimiters in the :ref:`ui-undo-redo-adjust-last-operation` panel,
+so the selection is constrained by seams, sharp edges, materials or UV islands.
+
+With *Pick Linked* you can also select connected geometry directly under the cursor,
+using the :kbd:`L` shortcut to select or :kbd:`Shift-L` to deselect linked.
 
-*Select Linked* will add to the selection the mouse cursor's nearest control point,
-and all the linked ones, i.e. all points belonging to the same surface.
+This works differently in that it uses the geometry under the cursor instead of the existing selection.
 
 
 Select Similar
-==============
+--------------
 
 .. admonition:: Reference
    :class: refbox
 
    :Mode:      Edit Mode
-   :Menu:      :menuselection:`Select --> Select Similar`
+   :Menu:      :menuselection:`Select --> Similar...`
    :Hotkey:    :kbd:`Shift-G`
 
-Selects control points that have certain similar properties to the active one.
-The :ref:`ui-undo-redo-adjust-last-operation` panel provides several selection options:
-
-Type
-   Type
-      Selects splines that have the same spline Type i.e. Bézier, NURBS or Poly.
-   Radius
-      Selects control points that have a similar Radius value.
-   Weight
-      Selects all points that have a similar Weight value.
+Select geometry that has similar certain properties to the ones selected,
+based on a threshold that can be set in tool properties after activating the tool.
+Tool options change depending on the selection mode:
+
+Vertex Selection Mode:
+   Normal
+      Selects all vertices that have normals pointing in similar directions to those currently selected.
+   Amount of Adjacent Faces
+      Selects all vertices that have the same number of faces connected to them.
+   Vertex Groups
+      Selects all vertices in the same :doc:`vertex group </modeling/meshes/properties/vertex_groups/index>`.
+   Amount of Connecting Edges
+      Selects all vertices that have the same number of edges connected to them.
+   Face Regions
+      Select matching features on a mesh that has multiple similar areas based on the topology.
+
+Edge Selection Mode:
+   Length
+      Selects all edges that have a similar length as those already selected.
    Direction
-      Selects control points that have a similar handles direction.
+      Selects all edges that have a similar direction (angle) as those already selected.
+   Amount of Faces Around an Edge
+      Selects all edges that belong to the same number of faces.
+   Face Angles
+      Selects all edges that are between two faces forming a similar angle, as with those already selected.
+   Crease
+      Selects all edges that have a similar :ref:`Crease <modeling-edges-crease-subdivision>`
+      value as those already selected.
+   Bevel
+      Selects all edges that have the same *Bevel Weight* as those already selected.
+   Seam
+      Selects all edges that have the same *Seam* state as those already selected.
+      *Seam* is a true/false setting used in :ref:`UV texturing <editors-uv-index>`.
+   Sharpness
+      Selects all edges that have the same *Sharp* state as those already selected.
+      *Sharp* is a true/false setting (a flag) used by
+      the :doc:`Edge Split Modifier </modeling/modifiers/generate/edge_split>`.
+
+Face Selection Mode:
+   Material
+      Selects all faces that use the same material as those already selected.
+   Image
+      Selects all faces that use the same UV texture as those already selected
+      (see :ref:`UV texturing <editors-uv-index>` pages).
+   Area
+      Selects all faces that have a similar area as those already selected.
+   Polygon Sides
+      Selects all faces that have the same number of edges.
+   Perimeter
+      Selects all faces that have a similar perimeter (added values of its edge lengths).
+   Normal
+      Selects all faces that have a similar normal as those selected.
+      This is a way to select faces that have the same orientation (angle).
+   Co-planar
+      Selects all faces that are (nearly) in the same plane as those selected.
+
+.. (todo) check type: Image in Cycles
+
+
+.. _modeling-meshes-selecting-edge-loops:
+
+Edge Loops
+----------
+
+.. admonition:: Reference
+   :class: refbox
+
+   :Mode:      Edit Mode --> Vertex or Edge select mode
+   :Menu:      :menuselection:`Select --> Select Loops --> Edge Loops`
+   :Hotkey:    :kbd:`Alt-LMB`, or :kbd:`Shift-Alt-LMB` for modifying existing selection.
+
+Holding :kbd:`Alt` while selecting an edge selects a loop of edges that are connected in
+a line end-to-end, passing through the edge under the mouse pointer.
+Holding :kbd:`Shift-Alt` while clicking adds to the current selection.
+
+Edge loops can also be selected based on an existing edge selection,
+using either :menuselection:`Select --> Edge Loop`.
+
+.. note:: *Vertex* mode
+
+   In *Vertex* select mode, you can also select edge loops, by using the same hotkeys,
+   and clicking on the *edges* (not on the vertices).
+
+.. figure:: /images/modeling_meshes_selecting_edge-loops.png
+
+   Longitudinal and latitudinal edge loops.
+
+The left sphere shows an edge that was selected longitudinally. Notice how the loop is open.
+This is because the algorithm hit the vertices at the poles and is terminated
+because the vertices at the pole connect to more than four edges. However,
+the right sphere shows an edge that was selected latitudinally and has formed a closed loop.
+This is because the algorithm hit the first edge that it started with.
+
+
+.. _modeling-meshes-selecting-face-loops:
+
+Face Loops
+----------
 
-Compare
-   Equal, Greater, Less. (only for Radius, Weight) (ToDo 2.76)
-Threshold
-   Precision (ToDo 2.76)
+.. admonition:: Reference
+   :class: refbox
+
+   :Mode:      Edit Mode --> Face or Vertex select modes
+   :Hotkey:    :kbd:`Alt-LMB` or :kbd:`Shift-Alt-LMB` for modifying existing selection.
+
+In face select mode, holding :kbd:`Alt` while selecting an *edge* selects a loop of
+faces that are connected in a line end-to-end, along their opposite edges.
+
+In vertex select mode,
+the same can be accomplished by using :kbd:`Ctrl-Alt` to select an edge,
+which selects the face loop implicitly.
+
+.. figure:: /images/modeling_meshes_selecting_face-loops.png
+
+   Face loop selection.
+
+This face loop was selected by clicking with :kbd:`Alt-LMB` on an edge,
+in *face* select mode.
+The loop extends perpendicular from the edge that was selected.
+
+.. figure:: /images/modeling_meshes_selecting_face-loops-vertex.png
+
+   :kbd:`Alt` versus :kbd:`Ctrl-Alt` in vertex select mode.
 
+A face loop can also be selected in *Vertex* select mode.
+Technically :kbd:`Ctrl-Alt-LMB` will select an *Edge Ring*,
+however, in *Vertex* select mode, selecting an *Edge Ring* implicitly
+selects a *Face Loop* since selecting opposite edges of a face implicitly selects
+the entire face.
 
-.. _bpy.ops.curve.select_row:
 
-Select Control Point Row
-========================
+Edge Boundary
+-------------
+
+.. admonition:: Reference
+   :class: refbox
+
+   :Mode:      Edit Mode --> Vertex or Edge select modes
+   :Hotkey:    :kbd:`Alt-LMB`
+
+Loop selection on edge boundaries.
+To extend the selection to all boundaries if the current boundary is already selected
+use :kbd:`Alt-LMB` again.
+
+
+Edge Ring
+---------
 
 .. admonition:: Reference
    :class: refbox
 
    :Mode:      Edit Mode
-   :Menu:      :menuselection:`Select --> Control Point Row`
-   :Hotkey:    :kbd:`Shift-R`
+   :Menu:      :menuselection:`Select --> Select Loops --> Edge Rings`
+   :Hotkey:    :kbd:`Ctrl-Alt-LMB`
 
-This option works a bit like
-:ref:`edge loop selection <modeling-meshes-selecting-edge-loops>` for meshes,
-inasmuch it selects a whole :ref:`row <modeling-surfaces-rows-grids>` of control points,
-based on the active (the last selected) one. The first time you press :kbd:`Shift-R`,
-the V row passing through (containing) the active point will be added to the *current* selection.
-If you use again this shortcut, you will toggle between the U and V row of this point,
-removing *everything else* from the selection.
+In *Edge* select mode, holding :kbd:`Ctrl-Alt`
+while selecting an edge (or two vertices) selects a sequence of edges that are not connected,
+but on opposite sides to each other continuing along a :doc:`face loop </modeling/meshes/structure>`.
 
+As with edge loops, you can also select edge rings based on current selection,
+using either :menuselection:`Select --> Select Loops --> Edge Rings`.
 
-Select More/Less
-================
+.. note:: *Vertex* mode
+
+   In *Vertex* select mode, you can use the same hotkeys when *clicking on the edges* (not on the vertices),
+   but this will directly select the corresponding face loop...
+
+.. _fig-mesh-select-advanced-loop-ring:
+
+.. figure:: /images/modeling_meshes_selecting_edge-ring.png
+
+   A selected edge loop, and a selected edge ring.
+
+In Fig. :ref:`fig-mesh-select-advanced-loop-ring` the same edge was clicked on,
+but two different "groups of edges" were selected, based on the different tools.
+One is based on edges during computation and the other is based on faces.
+
+.. note:: Convert Selection to Whole Faces
+
+   If the edge ring selection happened in Edge Select Mode, switching to Face Select Mode will erase the selection.
+
+   This is because none of those faces had all its (four) edges selected,
+   just two of them.
+
+   Instead of selecting the missing edges manually or by using :kbd:`Shift-Alt-` twice,
+   it is easier to first switch to Vertex Select Mode, which will kind of "flood" the selection.
+   A subsequent switch to Face Select Mode will then properly select the faces.
+
+
+Shortest Path
+-------------
 
 .. admonition:: Reference
    :class: refbox
 
    :Mode:      Edit Mode
-   :Menu:      :menuselection:`Select --> More/Less`
-   :Hotkey:    :kbd:`Ctrl-NumpadPlus` / :kbd:`Ctrl-NumpadMinus`
+   :Menu:      :menuselection:`Select --> Select Linked --> Shortest Path`
+   :Hotkey:    :kbd:`Ctrl-LMB`
+
+.. figure:: /images/modeling_meshes_selecting_shortest-path.png
+
+   Select a face or vertex path with :kbd:`Ctrl-LMB`.
+
+Selects all geometry along the shortest path from
+the active vertex/edge/face to the one which was selected.
+
+Face Stepping
+   Supports diagonal paths for vertices and faces, and
+   selects edge rings with edges.
+Topological Distance
+   Which only takes into account the number of edges of the path and
+   not the length of the edges to calculate the distances.
+Fill Region :kbd:`Shift-Ctrl-LMB`
+   Selects all elements in the shortest paths from the active selection to the clicked area.
+Checker Select Options
+   Allows to quickly select alternate elements in a path.
+
+   Nth Selection
+      Skip every Nth element, leave unselected.
+   Skip
+      Number of consecutive elements to skip at once.
+   Offset
+      Offset from the starting point.
+
+
+Loop Inner-Region
+-----------------
+
+.. admonition:: Reference
+   :class: refbox
+
+   :Mode:      Edit Mode --> Edge select mode
+   :Menu:      :menuselection:`Select --> Select Loops --> Select Loop Inner-Region`
+
+*Select Loop Inner-Region* selects all faces that are inside a closed loop of edges.
+While it is possible to use this operator in *Vertex* and *Face* selection modes, results may be unexpected.
+Note that if the selected loop of edges is not closed,
+then all connected edges on the mesh will be considered inside the loop.
+
+.. figure:: /images/modeling_meshes_selecting_inner-region1.png
+
+   Loop to Region.
+
+.. figure:: /images/modeling_meshes_selecting_inner-region2.png
+
+   This tool handles multiple loops fine, as you can see.
+
+.. figure:: /images/modeling_meshes_selecting_inner-region3.png
+
+   This tool handles "holes" just fine as well.
+
+
+Boundary Loop
+-------------
+
+.. admonition:: Reference
+   :class: refbox
+
+   :Mode:      Edit Mode --> Edge select mode
+   :Menu:      :menuselection:`Select --> Select Loops --> Select Boundary Loop`
+
+*Select Boundary Loop* does the opposite of *Select Loop Inner-Region*,
+based on all regions currently selected, it selects only the edges at the border(contour) of these islands.
+It can operate in any select mode, but when in *Face* mode it will switch to *Edge* select mode after running.
+
+All this is much more simple to illustrate with examples:
+
+.. figure:: /images/modeling_meshes_selecting_boundary-loop.png
+
+   Select Boundary Loop does the opposite and forces into Edge Select Mode.
+
+
+Known Issues
+============
 
-Expand or contract the selection based on current selected control points.
+N-Gons in Face Select Mode
+--------------------------
 
-More
-   For each selected control point, select **all** its linked points (i.e. two, three or four).
-Less
-   For each selected control point, if **all** points linked to this point are selected, keep it selected.
-   For all other selected control points, deselect them.
+.. figure:: /images/modeling_meshes_selecting_face-mode-ngon-visual-problem.png
 
-This implies two points:
+   N-gon face having its center dot inside another face.
 
-#. First, when **all** control points of a surface are selected, nothing will happen
-   (as for *Less*, all linked points are always selected, and of course, *More* cannot add any).
-   Conversely, the same goes when no control point is selected.
-#. Second, these tools will never "go outside" of a surface
-   (they will never "jump" to another surface in the same object).
+As already known, faces are marked with a little square dot in the middle of the face.
+With n-gons that can lead in certain cases to a confusing display.
+The example shows the center dot of the U-shaped n-gon being inside of the oblong face inside the "U".
+It is not easy to say which dot belongs to which face (the orange dot in the image is the object origin).
+Luckily, you do not need to care much, because to select a face, you do not have to click the center dot,
+but the face itself.

structure.rst.txt

@@ -3,95 +3,255 @@
 Structure
 *********
 
-Many of the concepts from :doc:`curves </modeling/curves/introduction>`,
-especially :ref:`NURBS <curve-nurbs>` ones,
-carry directly over to NURBS surfaces,
-such as control points, *Order*, *Weight*, *Resolution*, etc.
-Here we will just talk about the differences.
+With meshes, everything is built from three basic structures:
+*vertices*, *edges* and *faces*.
 
-It is very important to understand the difference between NURBS curves and NURBS surfaces:
-the first one has one dimension, the latter has two.
-Blender internally treats NURBS surfaces and NURBS curves completely differently. There are
-several attributes that separate them but the most important is that a NURBS curve has
-a single interpolation axis (U) and a NURBS surface has two interpolation axes (U and V).
+.. figure:: /images/modeling_meshes_structure_example.svg
+   :width: 600px
 
-However, you can have "2D" surfaces made of curves
-(using the :doc:`extrusion tools </modeling/curves/properties/geometry>`,
-or, to a lesser extent, the filling of closed 2D curves). And you can have "1D" curves made of surfaces,
-like a NURBS surface with only one row (either in U or V direction) of control points produces only a curve...
+   Example of mesh structure.
 
-Visually you can tell which is which by entering *Edit Mode* and looking at the 3D View header:
-either the header shows *Surface* or *Curve* as one of the menu choices. Also,
-you can :doc:`extrude </modeling/curves/properties/geometry>` a whole NURBS surface curve to create a surface,
-but you cannot with a simple NURBS curve.
+.. The geometry of the faces performing the model is called topology.
 
 
-.. _modeling-surfaces-rows-grids:
+Vertices
+========
 
-Control Points, Rows and Grid
-=============================
+The most elementary part of a mesh is the vertex vertices (plural) which is a single point or position in 3D space.
+Vertices are represented in the 3D Viewport in edit mode as small dots.
+The vertices of and object are stored as an array of coordinates.
 
-Control points for NURBS surfaces are the same as for NURBS curves. However,
-their layout is quite constraining. The concept of "segment" disappears,
-replaced by "rows" and the overall "grid".
+.. tip::
 
-A "row" is a set of control points forming one "line" in one interpolation direction
-(a bit similar to :ref:`edge loops <modeling-mesh-structure-edge-loops>` for meshes).
-So you have "U rows" and "V rows" in a NURBS surface.
-The key point is that *all* rows of a given type (U or V) have the *same* number of control points.
-Each control point belongs to exactly one U row and one V row.
+   Do not mistake the :doc:`object origin </scene_layout/object/origin>` for a vertex.
+   It may look similar, but it is bigger and cannot be selected.
 
-All this forms a "grid", or "cage", the shape of which controls the shape of the NURBS surface.
-A bit like a :doc:`lattice </animation/lattice>`...
+   .. figure:: /images/modeling_meshes_structure_cube-example.png
 
-This is very important to grasp: you cannot add a single control point to a NURBS surface;
-you have to add a whole U or V row at once
-(in practice, you will usually use the Extrude tool, or perhaps the Duplicate one, to add those...),
-containing exactly the same number of points as the others. This also means that you will only
-be able to "merge" different pieces of surfaces if at least one of their rows matches together.
+      The vertex is labeled as "A"; the object's origin dot is labeled as "B".
 
 
-.. _modeling-surfaces-weight:
+Edges
+=====
 
-Weight
-======
+An edge always connects two vertices by a straight line.
+The edges are the "wires" you see when you look at a mesh in wireframe view.
+They are usually invisible on the rendered image. They are used to construct faces.
 
-Similar to :ref:`NURBS Splines <curve-nurbs>` NURBS Surface control points have a weight property.
-This weight property controls how much influence the control point has on the surface.
-This weight should not be confused with the :ref:`Goal Weight <surface-goal-weight>`,
-which is used only for soft body simulations.
-The NURBS control point weight can be adjusted in the *W* number field of
-the :doc:`Transform panel </modeling/curves/editing/transform_panel>`.
 
-In Fig. :ref:`fig-surface-intro-weight` a single control point, labeled "C",
-has had its *Weight* set to 5.0 while all others are at their default of 1.0.
-As you can see, that control point *pulls* the surface towards it.
+Faces
+=====
 
-.. _fig-surface-intro-weight:
+Faces are used to build the actual surface of the object.
+They are what you see when you render the mesh.
+If this area does not contain a face,
+it will simply be transparent or non-existent in the rendered image.
 
-.. figure:: /images/modeling_surfaces_structure_weight.png
+A face is defined as the area between either three (triangles), four (quadrangles) or more (n-gons) vertices,
+with an edge on every side. The faces are often abbreviated to *tris, quads & n-gons*.
 
-   One control point with a weight of 5.
+Triangles are always flat and therefore easy to calculate. On the other hand,
+quadrangles "deform well" and are therefore preferred for animation and subdivision modeling.
+
+.. seealso::
+
+   - `Why should triangles be avoided for character animation? <https://blender.stackexchange.com/questions/2931>`__
+   - `When should N-gons be used, and when shouldn't they? <https://blender.stackexchange.com/questions/89>`__
+
+
+Normals
+=======
+
+In geometry, a normal is a direction or line that is perpendicular to something,
+typically a triangle or surface but can also be relative to a line,
+a tangent line for a point on a curve, or a tangent plane for a point on a surface.
+
+.. figure:: /images/modeling_meshes_editing_normals_viewport.png
+   :width: 350px
+
+   A visualization of the face normals of a torus.
+
+In the figure above, each blue line represents the normal for a face on the torus.
+The lines are each perpendicular to the face on which they lie.
+The visualization can be activated, in Edit Mode,
+in the :ref:`Mesh Display Viewport Overlays panel <mesh-display-normals>`.
+
+
+.. _modeling_meshes_editing_normals_properties:
+
+Properties
+----------
+
+.. admonition:: Reference
+   :class: refbox
+
+   :Panel:     :menuselection:`Properties editor --> Object Data --> Normals`
+
+.. figure:: /images/modeling_meshes_editing_normals_normals-panel.png
+
+   Normals panel.
+
+.. _auto-smooth:
+.. _bpy.types.Mesh.use_auto_smooth:
+.. _bpy.types.Mesh.auto_smooth_angle:
+
+Auto Smooth
+   Edges where an angle between the faces is smaller than specified in the *Angle* button will be smoothed,
+   when shading of these parts of the mesh is set to smooth. This is an easier way to combine smooth and sharp edges.
+
+   Angle
+      Angle number field.
+
+.. figure:: /images/modeling_meshes_editing_normals_example-auto-smooth.png
+   :width: 250px
+
+   Example mesh with *Auto Smooth* enabled.
+
+
+.. _modeling_meshes_normals_custom:
+
+Custom Split Normals
+--------------------
+
+*Custom Split Normals* is a way to tweak/fake shading by pointing normals towards
+other directions than the default, auto-computed ones. It is mostly used in game development,
+where it allows to counterbalance some issues generated by low-poly objects
+(the most common examples are low-poly trees, bushes, grass, etc. and the 'rounded' corners).
+
+Blender supports custom normals on a 'smooth fan' base, defined as a set of neighbor face corners
+sharing the same vertex and 'linked' by smooth edges. This means you can have normals per face corners,
+per a set of neighbor face corners, or per vertex.
+
+
+Enabling Custom Split Normals
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. admonition:: Reference
+   :class: refbox
+
+   :Mode:      Edit Mode
+   :Menu:      :menuselection:`Mesh --> Normals --> Split`
+
+Enables Custom Split Normals.
+
+Also, any of the custom normal editing tools (see below) will, as a convenience,
+enable custom normals if they are not already enabled.
 
 .. note::
 
-   If all the control points have the same *Weight* then each effectively cancels each other out.
-   It is the difference in the weights that cause the surface to move
-   towards or away from a control point.
+   This has the side effect of enabling :ref:`Auto Smooth <auto-smooth>`, as that is necessary to use custom normals.
+   Once you have custom normals, the angle threshold of the *Auto Smooth* behavior is disabled --
+   all non-sharp-tagged edges will be considered as smooth, disregarding the angle between their faces.
+
+
+Editing Custom Split Normals
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. admonition:: Reference
+   :class: refbox
+
+   :Mode:      Edit Mode
+   :Menu:      :menuselection:`Mesh --> Normals`
+   :Hotkey:    :kbd:`Alt-N`
+
+There are a number of tools for editing custom split normals.
+The custom normal mesh edit tools can affect all normals (the default), or only selected ones.
+To select a custom normal associated with a particular vertex and face:
+
+- Make the element selection mode both Vertex and Face (use :kbd:`Shift-LMB` to enable the second one).
+- Select one or more vertices, then select a face.
+  This can be repeated to select more vertices and a different face and so on.
+  It is easiest to see the effect of these tools if you turn on
+  the Edit Mode Overlays option *Display vertex-per-face normals as lines*.
+
+.. seealso::
+
+   :doc:`Editing Normals </modeling/meshes/editing/normals>`.
+
+
+Importing Custom Split Normals
+------------------------------
+
+Some tools, in particular :abbr:`CAD (Computer-Aided Design)` ones, tends to generate irregular geometry
+when tessellating their objects into meshes (very thin and long triangles, etc.).
+Auto-computed normals on such geometry often gives bad artifacts,
+so it is important to be able to import and use the normals as generated by the CAD tool itself.
+
+.. note::
+
+   Currently, only the :doc:`FBX Importer </addons/io_scene_fbx>` is capable of importing custom normals.
+
+
+Topology
+========
+
+.. Note: this could be it's own page, for now keep this a fairly brief section.
+
+Loops
+-----
+
+.. _fig-mesh-topo-loop:
+
+.. figure:: /images/modeling_meshes_structure_edge-face-loops.png
+
+   Edge and face loops.
+
+*Edge* and *face* loops are sets of faces or edges that form continuous "loops" as shown in
+Fig. :ref:`fig-mesh-topo-loop`.
+
+In the image above, loops that do not end in poles are cyclic (1 and 3).
+They start and end at the same vertex and divide the model into two partitions.
+Loops can be a quick and powerful tool to work with specific,
+continuous regions of a mesh and are a prerequisite for organic character animation.
+For a detailed description of how to work with loops in Blender, see:
+:ref:`Edge Loop Selection <modeling-meshes-selecting-edge-loops>`.
+
+.. note::
+
+   Note that loops (2 and 4) do not go around the whole model.
+   Loops stop at so-called poles because there is no unique way to continue a loop from a pole.
+   Poles are vertices that are connected to either three, five, or more edges. Accordingly,
+   vertices connected to exactly one, two or four edges are not poles.
+
+.. _modeling-mesh-structure-edge-loops:
+
+.. rubric:: Edge Loops
+
+Loops (1 and 2) in Fig. :ref:`fig-mesh-topo-loop` are edge loops.
+They connect vertices so that each one on the loop has exactly two neighbors that are not on
+the loop and placed on both sides of the loop (except the start and end vertex in case of poles).
+
+Edge loops are an important concept especially in organic (subsurface)
+modeling and character animation. When used correctly, they allow you to build models with
+relatively few vertices that look very natural when used as subdivision surfaces and
+deform very well in animation.
+
+Take Fig. :ref:`fig-mesh-topo-loop` in organic modeling as an example: the edge loops follow
+the natural contours and deformation lines of the skin and the underlying muscles and
+are more dense in areas that deform more when the character moves, for example at the shoulders or knees.
+
+Further details on working with edge loops can be found in
+:ref:`Edge Loop Selection <modeling-meshes-selecting-edge-loops>`.
+
+
+.. rubric:: Face Loops
+
+These are a logical extension of edge loops in that they consist of the faces between
+two edge loops, as shown in loops (3 and 4) in Fig. :ref:`fig-mesh-topo-loop`.
+Note that for non-circular loops (4)
+the faces containing the poles are not included in a face loop.
+
+Further details on working with face loops can be found in
+:ref:`Face Loop Selection <modeling-meshes-selecting-face-loops>`.
 
 
-Preset Weights
---------------
+Poles
+-----
 
-NURBS can create pure shapes such as circles, cylinders, and spheres
-(note that a Bézier circle is not a pure circle). To create pure circles, spheres,
-or cylinders, you must set to specific values the weights of the control points.
-This is not intuitive, and you should read more on NURBS before trying this.
+See `N-poles & E-poles <https://blender.stackexchange.com/a/133676/55>`__.
 
-To create a sphere with 2D surfaces, its the same principle as with a 2D circle.
-You will note that the four different weights needed for creating a sphere
-(1.0, 0.707 = sqrt(0.5), 0.354 = sqrt(2)/4, and 0.25).
 
-.. figure:: /images/modeling_surfaces_structure_weight-sphere.png
+Non-Manifold
+------------
 
-   A sphere surface.
+See :term:`Non-manifold`.