About Moving Control Points

You can deform a shape by moving its control points. When you move a control point, any other selected control points will also move. This section explains how the movement of the control point you are dragging is propagated to the other selected control points.

You use the Control Points command and the options in the Control Points dialog box to move a grid of control points on the surface of the shape; the movement of the control points deforms the surface.

You can choose to move the control points, the mesh lines which join the control points, or a mixture of both the control points and the mesh lines. This choice is determined by your selection in the Filters area of the Control Points dialog box (Points only, Mesh only or Points and mesh)

This section explains how control points move.

This page discusses:

  1. You move a control point by dragging it (or by editing its X, Y and Z coordinates).
  2. The direction or plane in which you can drag a control point is determined by the constraint selected in Support in the Control Points dialog box ( Normal to Robot, Mesh Lines, Local Normals, Robot plane, Local Tangents, Screen Plane).
  3. As you drag a control point, all other selected control points will move along the same constraint.
  4. The distance that any other selected control points move is determined by your selection in the Control Points dialog box in the Diffusion area only ( Constant Law, Linear Law, Concave Law, Convex Law, Bell Law).

Note: When you move a control point, Link Laws and any selection in the Cross Diff area have no effect and can be ignored.

The following examples highlight how the movement of the control point you are dragging is propagated to 4 other selected control points when different diffusion laws are selected in the Diffusion area. The illustration below shows the starting point of each example; the 5 selected control points can be seen highlighted in blue and the corner point is the one which is being dragged.

Note: After moving the selected control points, you can choose another diffusion law which will be directly applied to the selected control points.


Constant Law

The 5 control points have all moved through the same (constant) distance:

Linear Law

The 5 control points have moved by a linearly decreasing amount and now form a straight line:

Concave Law

The 5 control points have moved by a non-linear amount and now form a concave line:

Convex Law

The 5 control points have moved by a non-linear amount and now form a convex line:

Bell Law

The 5 control points have moved by a non-linear amount and now form a bell shape line:

Define the Strength of Diffusion Between Laws

After choosing the diffusion law and moving the selected point, a handle appears next to the moved point. You can define the strength of the diffusion and choose directly another diffusion law impact.

The diffusion laws are regrouped in two categories: Concave, Convex, and S curve . The strength handle values vary between 0 and 1. A value of 0.5 corresponds to a linear diffusion.

  1. Concave and convex: 0 to 0.5 values correspond to a concave diffusion (the closer to 0, the stronger is the diffusion). 0.5 to 1 values correspond to a convex diffusion (the closer to 1, the stronger the diffusion).
  2. S curve (Bell): 0 to 0.5 values correspond to an S curve diffusion (the closer to 0, the stronger is the diffusion). 0.5 to 1 values correspond to an opposite S curve diffusion (the closer to 1, the stronger the diffusion).

For the following example, the diffusion is set to Linear Law and the strength handle is moved along the displayed ruler:







Linear diffusion (Strength set to 0.5) Concave diffusion (Strength set to 0.2) Convex diffusion (Strength set to 0.7)

 

See Also
About Deforming a Shape Using Control Points
About Moving Mesh Lines
Moving Control Points
Positioning Control Points