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The behaviour of the FOV determination is controlled by the arguments supplied to the method ShadowCasting.ComputeFIeldOfView():
    /// <summary></summary>
    /// <remarks>
    /// Takes a circle in the form of a center point and radius, and a function
    /// that can tell whether a given cell is opaque. Calls the setFoV action on
    /// every cell that is both within the radius and visible from the center. 
    /// </remarks>
    /// <param name="observerCoords">Cordinates of observer;s hex.</param>
    /// <param name="radius">Maximum radius for Field-of-View.</param>
    /// <param name="observerHeight">Height (ASL) of the observer's eyes.</param>
    /// <param name="targetHeight">Returns ground level (ASL) of supplied hex.</param>
    /// <param name="terrainHeight">Returns height (ASL) of terrain in supplied hex.</param>
    /// <param name="setFoV">Sets a hex as visible in the Field-of-View.</param>
    public static void ComputeFieldOfView(
      ICoordsCanon            observerCoords, 
      int                     radius, 
      int                     observerHeight,
      Func<ICoordsCanon,bool> isOnBoard,
      Func<ICoordsCanon,int>  targetHeight, 
      Func<ICoordsCanon,int>  terrainHeight,
      Action<ICoordsCanon>    setFoV
) { /* ... */ }
  • It is important for realisism that observerHeight > board[observerCoords].ElevationASL, or no parallax over the current ground elevation will be observed.
  • TerrainHeight is the ElevationASL plus the height of any blocking in the hex, usually due to terrain but sometimes occuppying units will block vision as well. Control this in the implementation of IBoard.
  • If the height unit is taken as 5', then the contour levels on the Terrain Map are at 50' (5' * 10) and the woods generate a terrain height of 35' (5' * 7). The observer and target will then be at ElevationASL + 5'.
  • If symmetry is desired (which is normal when testing and perhaps for speculative FOV determination in a game situation) then the function used to determine the targetHeight should be the same as that used to determine observerHeight
  • By default the engine supplies three target modes, and uses the first in the examples:
        switch (targetMode) {
          case FovTargetMode.EqualHeights: 
            observer = board[origin].ElevationASL + 1;
            target   = canon => board[canon.User].ElevationASL + 1;
            break;
          case FovTargetMode.TargetHeightEqualZero:
            observer = board[origin].HeightObserver;
            target   = canon => board[canon.User].ElevationASL;
            break;
          default:
          case FovTargetMode.TargetHeightEqualActual:
            observer = board[origin].HeightObserver;
            target   = canon => board[canon.User].HeightTarget;
            break;
        }
        if (observer > 0) 
          ShadowCasting.ComputeFieldOfView(
            origin.Canon, 
            range, 
            observer,
            canon=>board.IsOnBoard(canon.User),
            target,
            canon=>board[canon.User].HeightTerrain,
            canon=>fov[canon.User] = true
          );

Last edited Feb 26, 2013 at 11:33 PM by pgeerkens, version 4