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# 2.2.8.8 Cornu Easements Modifying a Cornu Track

Because a Cornu Track is defined by its end points position, angle and radius - it can only be directly modified by dragging an end point along a track, or altering its end conditions if it is not joined to another track. It can also have added "Pins" which constrain the curve to smoothly pass through a point.

1. Click the Modify button () to activate the Modify function.

2. Click on the Cornu track. The track ends will turn into roundels. If any other Cornus are connected at either end, the entire connected set will be modifyable as one Cornu with intermediate "Pins" at the connections.

3. Left-Click an endpoint and Left-Drag it to move the endpoint along a connected track, or beyond it if you want that track extended. If there is no track the endpoint is free to move.

4. For an unconnected end point, Left-Click on the Radius or Angle anchors and Left-Drag it to adjust them.

5. Left-Click an Pin and Left-Drag it to move the pin and make the curve to pass through it.

6. Left-Click the track where a Pin doesn't exist to add a Pin and Left-Drag it to alter the curve to pass through a defined point.

7. Delete to delete the last seelcted Pin, the curve will change to meet the end conditions and pass through any remaining Pins.

8. Repeat with the other end-point or Pins if desired

9. Once you are happy, hit the spacebar or Enter, or to cancel hit Escape.

Note: If the Modify command contained Pins, spacebar or Enter it will output a set of connected Cornu(s) joined at the Pin points.

Note: A Cornu can also be modified by moving or rotating a connected track.