Trapezoidal Decomposition

How to use it:

This page provides an interactive Java version of the trapezoidal decomposition. It is only defined for simple polygons, that is where no two edges intersect, except where neighbouring edges meet at a vertex.

Use it as follows:

• Click anywhere in the applet region below, to start drawing a polygon, let go of the mouse button, move the mouse and a rubber band line will start.
• Each time you click, a new point will be added to the polygon.
• Click on the "Stop" button to end the polygon at the previous vertex.
• The "Reset" will clear the drawing area and allow a new one to be created.

Important note:

There is a bug, that occurs sometimes, but unpredictably. When this happens the polygon is filled but no trapezia are shown. The bug seems to be to do with the speed at which the user inputs points! Maybe data is being lost on the network when the clicks are in too rapid succession.

Sources:

The Java implementation makes extensive use of the LinkedList class of the corejava package described in G. Cornell and C.S. Horstmann, Core Java, 2nd Edition, 1997, The SUNSOFT Press, Java Series.

Mel Slater, November 1997.