﻿ Step 16.1: About the Blend-Curve & Motion-Path FB

# Step 16.1: About the Blend-Curve & Motion-Path FB

### Compare a Motion-Part to a Motion-Point

A Motion-Part and a Motion-Point are similar elements:

 • Motion-Part, is a Part, whose motion is constrained by a joint, whose position is identified by its Motion Dimension, and whose motion is defined by the input to the Motion-Dimension FB.
 • Motion-Point, is a Point, whose motion is constrained by a sketch, whose position is identified by its Motion-Point Dimension, and whose motion is defined by the input to the Motion-Path FB.

#### The Motion-Path FB and Motion-Dimension FB - compared

Motion-Path FB & Motion-Point:  'Add Motion-Path FB' does three things:

 1 Adds a Motion-Point to a prepared sketch-element [or sketch-path]
 2 Adds a Motion-Path FB to the graphic-area
 3 Adds a dimension to the Motion-Point FB to indicate how far the Motion-Point has moved along the sketch-path.

Note:

To see the Motion-Point Dimension you must:

 1 Edit the Motion-Path FB, and
 2 Click the Displacement radio-button in the  Point List and Data Display  separator of the Motion-Path FB dialog-box.

The displacement of the Motion-Point along the sketch-path shows above the Motion-Path FB.

Motion-Point: is a Point constrained by a sketch-path. Its position from the start-Point of a sketch-path is the total of values given by:

 • Motion-values at the input-connector of the Motion-Path FB
 • Base-Value, as entered in the Point Parameters separator Motion-Path FB dialog-box.

Motion-Dimension FB & Motion-Part. 'Add Motion-Dimension FB' does three things:

 1 Specifies the position of a sketch-element [Line or Point] in a Motion-Part relative to another sketch-element [Line or Point] in another Part
 2 Adds a Motion-Dimension FB to the graphic-area.
 3 Adds a Motion Dimension between the sketch-elements in the two Parts.

Motion-Part: is a Part constrained by a joint. Its position from a sketch-element in a different Part, is the total of values given by:

 • Motion-values at the input-connector of the Motion-Dimension FB.
 • Base-Value as entered in the Motion-Dimension FB dialog-box.

#### Why use a Blend-Curve A Blend-Curve is a sketch-element.  A Blend-Point has a start-Point and an end-Point.

Use the Blend-Curve dialog-box to specify, at its start-Point and its end-Point, these parameters:

 o Angle
 o Curvature
 o Rate-of-Change of Curvature

You can also specify a 'normalisation' parameter we call Velocity-Scaling. This controls the overall length and shape of the Blend-Curve.

Question: Why do we need a Blend-Curve?