BLAG provides several visibility layout algorithms. If you want to construct a visibility drawing of a graph with BLAG, simply do the following:

Note: the current version of GDT allows to apply code 8 only to graphs that are biconnected. A graph is biconnected if the removal of one node is not sufficient to cut it into two (or more) disconnected pieces.

An example of visibility drawing constructed with the previous steps is shown in the following figure.

 

 

You can also apply an algorithm to draw directed graphs using "visibility-upward" layouts. Use for example the following file configuration:

An example of "visibility-upward" drawing of a graph, produced with the above configuration file, is shown in the next figure:

 

 

Several strategies are available for producing visibility drawings that are more or less compact. They have assigned an integer number in the interval 0 - 7. If no specification is given, then compaction 7 is applied as a default. If you want to force BLAG to use a certain compaction strategy, different from 7, you have to specify it as follows:

In this case BLAG will use the compaction strategy number 3. Usually, the best strategies, from the aesthetics point of view, are 2, 3, 6, and 7. On the other hand they are more time consuming than 0, 1, 4, and 5. Strategies 3 and 7 are strongly recommended for applications where having very compact drawings is a strict requirement.

 


Last update : July 31 2002
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