If an object is not 'generated' before it is 'rendered', it will not show up. Any OMGraphic classes can be extended to create different graphic types, or to increase the functionality of the graphics. OMGraphics are created based on a rendering type. Great Circle lines represent the shortest distance between two points on a globe. Rhumb lines represent lines of constant bearing.
Straight lines represent the shortest screen distance between two points.
The OMGraphicList can be used to manage groups of OMGraphics. OMGraphicLists are actually OMGraphics themselves, so they can be used to hold several OMGraphics to make up a complex graphic, and then added to another OMGraphicList. When creating a layer, you have to be aware of the effects that your layer will have on the overall performance of OpenMap. The layers are swing components, and are added as child components to the MapBean. Since the layers receive this call via the event thread of the application, any large amount of work that takes place at this time will significantly slow down the responsiveness of OpenMap.