Tour 3: String Art

Ideas in this tour:

·        How to start a simple animation.

·        How to use the Motion Controller to control an animation.

·        How to trace an object.

·        How to use the Context menu to access certain commands.

·        How to create an Animation action button.

Selecting and Tracing

1.      Open the sketch String Art.gsp from the Tours folder.

You’ll see two points constructed on a rectangle and connected by a yellow segment.  Think of the segment as a length of string.  The plan is to put the string in motion and study its “traces.” 

The applet below is to give you some idea of what this is and where you're headed.  Click the animate button to start and stop the animation.  When it's going you'll see some points moving around the rectangle with a blue line between them.  Try stopping the animation and dragging corners of the rectangle and the two animated points around and then animating them again.

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2.      Select the blue  segment by clicking on it with the Arrow tool.

3.      Choose Animate from the Display menu.
The segment will begin moving around the rectangle and the Motion Controller will appear.

4.      Experiment with the buttons on the Motion Controller.  In particular, press the Increase Speed and Decrease Speed buttons and the Reverse Directions button.  A good speed is

somewhere around 3 or 4.  You can also grab and drag bits elements of the sketch around.  Have a ball, but before proceeding to the next step, press pause (unless you think you can catch the segment on the run!), click on a blank region of the sketch to deselect all and then click on the yellow segment again.

5.      Press pause again reanimate the segment if it is paused and  choose Trace Segment from the Display menu to see the trace of the segment’s path as it animates.  Try out different colors.

6.      Experiment with animating various components of the sketch.  You can get the two ends of the segment running in different directions and have the corners of the quadrilateral (it’s not necessarily rectangular) jiggle around randomly

7.       Under Preferences from the Edit menu you can go to the Color panel change the speed of the Fade Traces effect, or deselect it entirely in the check box.

 Making an Animation Action Button.


The easiest way to start an animation is with the Animate command or the Animate button on the Motion Controller, but if you want to reproduce a particular pattern with preset speeds and direction settings, Animation action buttons give you more control.


8.      Click in a blank space (to avoid specifying in particular motion) and press the Stop button on the Motion Controller to stop all motions. 

9.      With all other objects deselected, select the (is it still yellow?) “string” segment.    Now from the Edit menu choose Animation from the Action Buttons submenu.

Note that you can learn about this dialog box by using Sketchpad’s help system.  Click the Help button to access the help topic for this  command.  Your default browser should launch—though my Internet Explorer gives the odd message “Your browser does not support frames.”  You can search by chapter or index.  Under “index,” for instance, there are many entries under “action.”

10.  The Animate Properties dialog box allows you to preset speed and direction for various combinations of sketchpad objects.  Try a combination and click “Ok.”  An Animation button will appear in the Sketchpad document.  You can reposition the button by dragging its handle (left side) and you can change its properties by right clicking and selecting “properties” from the popup menu.

11.  Try adding more animation behaviors with other buttons. Make sure just the objects (points, segments, etc) you want to animate are selected before choosing Edit/Action Buttons/Animate.  Go crazy!