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Manual - Blender 2.45

[edit] Pivot

Pivot Point modes.

The pivot point is the point in space around which all rotations, all scalings and all mirror transformations are centered. You can chose among five general modes for your pivot points which can be selected from a drop-down list in the header of any 3D area, as seen here in (Pivot Point modes). Your job is to choose the most efficient type for the task and to position pivot point accurately.

[edit] Active Object

Forget the name: it is not limited to objects. In Edit mode the active element can also be a vertex, an edge or a face.

[edit] In Object mode

Rotation around the active Object.

What happens in Object mode is pretty simple: rotations and scalings happen around the active Object’s center. This is illustrated by (Rotation around the active Object), where the center of the active Object, an hourglass, is the only thing to remain still.

[edit] In Edit mode

It may seem like there is a lot of complexity to using the active element as a pivot point in Edit mode but, in reality, the many possibilities result of only a few rules:

• The pivot point is always at the median of the active element(s).
• The transformations occur by transformation of the vertices of the selected element(s). If an unselected element shares one or more vertices with a selected element then the unselected one will get some degree of transformation also.

Let’s examine the following examples: in each case we will see that the two rules apply.

[edit] Single selection

Edit mode and only one element selected.

When one single element is selected it becomes automatically active. In (Edit mode and only one element selected), you can see that when it is transformed its vertices move, with the consequence that any adjacent element which shares one or more vertices with the active element is also transformed somewhat.

Lets review each cases:

• Faces have their pivot point where their selection dot appears, which is where the median of their vertices is.
• Fgons behave the same, but notice that the selection dot can be off compared to faces.
• Edges have their pivot point on their middle since this is always where the median of an edge is.
• A single Vertex has no dimensions at all so it can’t show any transformation (except translation, which is not affected by the pivot point…).

[edit] Multiple selection

Edit mode and multiple selections.

When multiple elements are selected they all transform.

The pivot points stay in the same place as what we’ve seen above, with only one exception for Fgons. In (Edit mode and multiple selections), the selected elements have been scaled down from large to small:

• For Faces the transformation occurs around the selection dot of the active face.
• Fgons behave exactly like faces.
• Edges also keep the same behavior with their pivot point at their median.
• There is a case for Vertices this time: the active Vertex is where the pivot point resides. All other vertices are transformed relative to it.

Again, as we have seen, all there is to remember is the two rules:

• Pivot point at the median of the active element’s vertex or vertices.
• All selected vertices, directly or as part of a bigger element, e.g. a face, and only them are transformed.

[edit] Individual Center

[edit] In Object mode

Rotation around the individual centers.

In (Rotation around the individual centers), the object centers of each object remains at the same location while each object is rotating around them.

Positioning the center of the objects is a most useful technique that affords you more control over your animations. Let’s examine (Rotation around the individual centers):

• The center of the hourglass is coincident with the median of all its components.
• The positioning of the center of the star at the tip of one of its branch allows for a rotation around it with only the use of Rot Ipos that are more faithfully interpolated than what you get using the 3D cursor in the same position.
• The center of the crescent is completely outside of what to us appears to be the object. You must understand that the center really marks where the object is; what we see on the screen is a description of what the object is made of: vertices, colors, stuff, and it can very well happen to be off-center, like for the crescent here.

[edit] In Edit mode

With the vertex or the edge selection methods in use, a selection of vertices or of edges has its pivot point at the median of the set of vertices so selected. For more information see the Median Point pivot section.

As soon as the face selection method is in use though, the pivot point as the center of those faces becomes possible.

Individual rotation of multiple faces.

It is possible to rotate individually each face only in face selection mode. Only faces that don’t touch each other can be transformed in this way without deforming. You cannot use the Proportional Editing Tool (PET) while transforming individual faces this way.

Fgon rotation with individual centers pivot point.

Faces that touch, even when they are inside an Fgon, are deformed when rotated with individual centers as the pivot point.

Problems with Fgon and groups of faces scaling.

Fgons and groups of faces can be scaled and their outside perimeter won’t be deformed. The individual faces inside them aren’t uniformly scaled though, something you should take into account.

All those deformations won’t happen if you are not using the face selection mode; it becomes impossible to edit more than one face or one group of faces at a time though.

Modelisation with faces and individual centers pivot point.

Once you are aware of its limitations and pitfalls, this peculiar tool can save a lot of time and lead to unique shapes. This “anemone” was modeled from a 12 sided cylinder in about 10 minutes by using repeatedly this workflow: extrusions of individual faces, scaling with median as a pivot point, and scaling and rotations of those faces with individual centers as pivot points.

[edit] 3D Cursor

The 3D cursor is the simplest most intuitive of all pivot points, it allows for total control of the results. It can be summarize by this: position it and transform.

[edit] Positioning the 3D cursor

There are a few methods to position the 3D cursor.

Positioning the 3D cursor with two orthogonal views.

• Using CtrlLMB in the 3D area. For accuracy you should look and use two orthogonal (perpendicular) 3D areas, any combination of top (Ctrl7 NumPad), front (Ctrl1 NumPad) and right side (Ctrl3 NumPad) is the easiest to access. That way, in one view you can control the positioning along two axes and determine depth in the second view.

The Snap menu.

• Using snaps:
  • ⇧ ShiftS → Cursor -> Grid to send the 3D cursor to the nearest visible point of the grid.
  • ⇧ ShiftS → Cursor -> Active to send the 3D cursor to the active (last selected) object, edge or face center, or to the active vertex.
  • ⇧ ShiftS → Cursor -> Selection to send the 3D cursor to:
    • The object center of an object.
    • A vertex.
  • When there is more than one element in the selection and the Bounding Box Center pivot point is selected, ⇧ ShiftS sends the 3D cursor to:
    • In Object mode, to the center of the bounding box surrounding the objects centers.
    • In Edit mode, to the center of the bounding box surrounding the selected vertices (even in edge or face selection mode, it really is the vertices that are selected indirectly that are taken into account).
  • When the Median Point pivot point is selected, ⇧ ShiftS sends the 3D cursor to:
    • In Object mode, to the median of the object centers.
    • In Edit mode, to the median of the selected vertices.

Lots of possibilities is lots of power!

The View Properties panel.

• Numerically, you can use the View Properties... entry of the View menu (from the 3D view header), and then enter the 3D Cursor location in the 3D Cursor section of the resultant View Properties panel that should now be visible.

[edit] Transformation

All there’s left to do is to select the 3D Cursor as the pivot point and rotate, scale or mirror.

[edit] Median Point

We can assimilate the “median point” to the notion of Center Of Gravity (COG): supposing that every element of the selection has the same mass, the median point would sit at the COG, the point of equilibrium for the selection. This is very abusive as we will see soon enough. Yet it helps predicting where the median point should be when planing a scene.

Median point of object centers and ObData.

[edit] In Object mode

For objects, only the object center is taken into account. Moreover, each object center is assumed to have the same mass. This can lead to very counter-intuitive results. On the (Median point of object centers and ObData), we see that the median of the objects sits far from the middle of the object centers. That is because the ObData (the geometry) of the moon and the star is way off their object center.

[edit] In Edit mode

Still on (Median point of object centers and ObData), we see that even the position of the median point for the ObData is surprisingly close to the hourglass: this is because it has much more vertices (611) than the moon (81) and the star (130). Blender supposes that every vertex has the same weight.

[edit] Transformation

Once the Median Point has been chosen from the list, the transform manipulator (if enabled) immediately cling to it, giving and excellent visual clue: all the rotations, scalings and mirror will happen around this point.

[edit] Bounding Box Center

The bounding box is a rectangular box that is wrapped as tightly as possible around the selection. It is oriented parallel to the world axes. In this mode the pivot point lies at the center of the bounding box.

[edit] In Object mode

The bounding box in Object mode.

In Object mode, the bounding box is wrapped around the object centers and does not take into account the ObData (geometry).

[edit] In Edit mode

The bounding box in Edit mode.

This time it is the ObData that is enclosed in the box because all of its vertices were selected. The bounding box in Edit mode takes no account of the objects centers but only of the selected vertices.

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