A radar marker is a generic radar specific object controlled by the server. It is used to flag things such as the location of team flags, and hunted targets. There is also a proposed map object that would allow maps to define arbitrary markers in the map.
The object will contain a sub-type and associated data.
The client will then display each subtype on the radar view only. Unknown sub-types will be ignored. All 3d point data would be in world space, with the objects being drawn in Z order ( lowest to highest ) in orthographic projection with the map.
By taking the maker logic off of the server, we can make the logic be more customizable by the servers' game logic and plug-ins. Addin an option to tie a marker to the location of a specific moving object (tank) would allow for a number of gameplay variations.
The client would only need to know how to draw a number of generic marker types ( various shapes ) in a server defined color. The server would simply send a marker message to the client with postional data ( and an attachment object if desired ). The client would then not need to know what this marker is, but simply store it and draw it every frame. Some radar marker types could also have HUD marker components ( flag and hunt ), this should be optional.
By using a separate message system for the markers that is not tied to the map file, the game can send out dynamic updates to the markers while the game is running. This can allow for additional game play modes such as domination, where the controlled base is flagged on the radar with the appropriate color.