3D Compositing with Action > Action: Masks > Manipulating Vertices and Tangents >
Transforming a Selection of Vertices

You can select multiple vertices in a mask and transform them as a group using the parameters. With the exception of translating vertices, transformation results are dependent on the position of the pivot point, displayed as a green or red circle in the image window. All transformations can be animated.

Transformation box
  Select the type of modification that is permitted on the selected vertices. You can translate, rotate, scale or shear the selection. In the image window, the pivot icon indicates the transformation type.

Pivot Type box
  Select the position of the pivot point.

  Select: | To:
  --- | ---
  Centroid | Set the pivot in the centre of the mask.
  Selection | Set the pivot in the centre of the vertex selection.
  Manual | Set the pivot gesturally. Drag the pivot at any time to automatically enable this option. A red pivot indicates a manual transformation.

X and Y Selection fields
  Displays the position of the selected vertex. When multiple vertices are selected, the position of the earliest created vertex is displayed.

X and Y Translate fields
  Displays the translation of the selected vertex. Enabled when the Transformation box is set to Translate.

X and Y Scale fields
  Displays the scale value of the selected vertices. Enabled when the Transformation box is set to Scale.

X and Y Shear fields
  Displays the shear value of the selected vertices. Enabled when the Transformation box is set to Shear.

Proportional buttons
  Enable to change the Scale or Shear fields proportionally.

Rotation field
  Displays the rotation value on the pivot of the selected vertices. Enabled when the Transformation box is set to Rotate.

To transform a localized selection of vertices:

1. Select the node of the mask you want to edit.
2. Ctrl-drag over the vertices that you want to transform as a group.
3. Click the Vertices button.
4. Select an option from the Transformation box.

   Fields associated with the transformation type will be enabled.

5. Select an option from the Pivot Type box. (If Translate is selected as the transformation type, the box is disabled.)
   NoteIf the pivot point is selected, the position can also be moved by editing the X and Y Selection fields.
6. Do either of the following:
   - The active fields can be used to transform the selection.
   - Move the selection gesturally in the image window.