InteractiveOrganicLayout

Besides the organic graph arrangement, this algorithm enables to immediately visualize changes made to a graph. Changes can be read back and the layout will be locally updated. That way, live interactions with an adapting graph layout are possible. Another advantage is that it is not necessary to compute a completely new layout if only small changes were made.

Layout Style

This algorithm supports the organic layout style which is characterized by a natural distribution of nodes. It is well suited to exhibit clusters and symmetric properties of a graph. Nodes are placed in a space-saving manner and distances between neighbors are highly uniform. Edges maintain uniform lengths too and are routed with straight-line segments without bends.

Organic diagrams are well suited for visualizing relations in large networks, for example, in bioinformatics, enterprise networking, social networks visualization, mesh visualization or system management.

Organic layout obtained using this algorithm

Concept

The internal basis for computing actual layouts is a force-directed approach placing the nodes of the input graph. The graph is modeled as a physical system with appropriate forces acting on it. Nodes are considered as electrically charged particles with mutually repulsive forces. Edges are modeled as forces that attract adjacent nodes. A good diagram is obtained from an equilibrium state of the system, i.e., the nodes are rearranged based on the physical forces until the system reaches a (local) minimum of the sum of the forces.

Importantly, changes will not be automatically applied to the input graph. To commit updates, it is required that a InteractiveOrganicNodeHandle for each node is provided in a mapper registered with key NODE_HANDLE_DATA_KEY. The algorithm will then write positions into the handle instance, which must then be manually transferred to the actually displayed graph (e.g. as part of an animation that transfers positions regularly).

Features

Several update methods on the InteractiveOrganicNodeHandle allow to indicate lightweight changes on the graph, for example, setCenter for node location updates. These updates will be scheduled and executed at a specific point within the life-cycle of the layout algorithm. They are ideally suited for usage in interactive scenarios, where users, for example, change node positions in the displayed graph via mouse-dragging.

Usage Hints

Start the algorithm using startLayout. Furthermore, it is strongly recommended to start it by passing a copy of the original graph as argument to the mentioned method.