1.3 Concept of usage

The initial concept of usage matches roughly the one of Geometers Scetchpad and KSEG:First mark the given objects, then construct the object that depends on them. Example: Select two lines, then press ’point’ and get the intersection.

Advantage:

If you know what you are doing, you can construct your scene very quickly, especially when using keyboard-shortcuts. In the following table the construction of a sphere is compared to the consruction of a cirle with Euklid DynaGeo:

Sphere wih Archimedes	Circle with Euklid
Double-right-click to get a free point	Shift-click on the point-symbol
Double-right-click to get a free point	Click on the canvas to get a free point
Click on the first point	Click on the canvas to get a free point
Shift-click on the second point	Click on the circle-symbol
Click on the sphere-symbol	Click on the first point
	Click on the second point

When using tricks like ’shift-double-right-click’ for generating and selecting simultaneously you can even save two more steps with Archimedes. The more often you change the kind of object to construct, the more steps you save with Archimedes.

Disadvantage:

This concept is unintuitive, as you have to know what objects you needbefore you construct your new object.

As a result of this disadvantage, I have built in a second possibility to construct objects.

If you click on the ’point’-button, the program decides depending on which objects are selected:

• If suitable objects for constructing a point are selected, two lines for instance, the dependent point is constructed at once (the intersection of the two lines in our example).
• If no suitable objects for constructing a point are selected, a menu pops up which lets you choose which kind of point should be constructed. After this, the program displays (in the status bar and directly in the graphics window) which kind of object you should click on. You can interrupt this construction by pressing Escape.

All possibilities to construct objects are accessible in the menu ’New Object’. This is a good place to get an impression of what can be done with Archimedes Geo3D. If you take this way for constructing, the marked objects are not taken into consideration no matter if they match or not.

In addition there are the ’intelligent’ buttons in the smaller toolbar (see the section on the smaller toolbar ).