Fog of War and Visibility

While the game engine itself maintains the complete MAP and knows where all UNITs, BUILDINGs, etc. are, the players do not have total knowledge. The JCiv game implements ``fog of war'': the players can see only what their UNITs have seen or are currently seeing. There are three levels of fog of war:

UNSEEN

A CELL that has never been seen by any unit is UNSEEN. The UI MUST NOT reveal any information about the contents of an UNSEEN CELL (including its TERRAIN TYPE) to the PLAYER. For example, an UNSEEN CELL MAY be rendered as a featureless black square.

WATCHED

A CELL that is currently in the VIEWING RADIUS of some UNIT is WATCHED. The entire contents of a WATCHED CELL (including TERRAIN TYPE) MUST be displayed to the PLAYER. For example, the UI MAY render the TERRAIN TYPE as a background image and layer information about UNITs and BUILDINGs onto that image.

PREVIOUSLY VIEWED

A CELL that was WATCHED at some point in the past, but is not currently being WATCHED is PREVIOUSLY VIEWED. The UI MUST display the TERRAIN TYPE of any PREVIOUSLY VIEWED CELL, but MUST NOT display the current UNIT or BUILDING contents of that CELL. The UI SHOULD make some visual distinction between CELLs that are currently WATCHED and those that are PREVIOUSLY VIEWED. For example, it MAY display a PREVIOUSLY VIEWED CELL as a ``grayed out'' tile.

OPTIONAL RULE: The UI MAY display whatever the last known contents of the CELL were, so long as the display is not updated to correspond to the current contents of the CELL.

Note that a player can always see all of his/her UNITs and BUILDINGs and the TERRAIN TYPEs and other contents of the CELLs within the VISION RADIUS of any of his/her UNITs/BUILDINGs.