private bool TryAddFiringLineNodesWithNextShortestDistance(
TwoValuedCircularBuffer <Node> bfsQueue, FiringLineSummary[,] firingLineSummariesByMovementDirAndEdgeOffset,
out int newDistance)
{
bool canAddMoreNodes = false;
int nextShortestDistance = Constants.UNREACHABLE_DISTANCE;
foreach (Direction movementDir in MovementDirections)
{
foreach (EdgeOffset edgeOffset in EdgeOffsets)
{
FiringLineSummary firingLineSummary = firingLineSummariesByMovementDirAndEdgeOffset[(int)movementDir, (int)edgeOffset];
if (firingLineSummary.NextEdgeWeighting < nextShortestDistance)
{
nextShortestDistance = firingLineSummary.NextEdgeWeighting;
canAddMoreNodes = true;
}
}
}
if (!canAddMoreNodes)
{
newDistance = Constants.UNREACHABLE_DISTANCE;
return(false);
}
newDistance = nextShortestDistance;
return(TryAddNextFiringLineNodesToQueue(bfsQueue, firingLineSummariesByMovementDirAndEdgeOffset, newDistance));
}
private void AddNextFiringLineNodesToQueueForMovementDirAndEdgeOffset(
TwoValuedCircularBuffer <Node> bfsQueue, Direction movementDir, EdgeOffset edgeOffset,
FiringLineSummary firingLineSummary, int distanceToAdd)
{
Line <FiringDistance> firingLine = firingLineSummary.FiringLine;
int nextFiringLineIndex;
for (nextFiringLineIndex = firingLineSummary.IndexOfNextFiringLinePoint;
nextFiringLineIndex < firingLine.Length;
nextFiringLineIndex++)
{
if (nextFiringLineIndex == -1)
{
return;
}
FiringDistance firingDist = firingLine[nextFiringLineIndex];
int nextEdgeWeighting = firingDist.TicksTillTargetShot - 1;
// This distance is the edge weight in the graph.
// The -1 is because we need to compensate for the weight 1 edge added from
// the tank's position + direction on the firing line, to the firing line node.
if (nextEdgeWeighting > distanceToAdd)
{
firingLineSummary.NextEdgeWeighting = nextEdgeWeighting;
firingLineSummary.IndexOfNextFiringLinePoint = nextFiringLineIndex;
return;
}
if (!TurnCalculationCache.CellMatrix[firingDist.StartingTankPosition].IsValid)
{
firingLineSummary.NextEdgeWeighting = Constants.UNREACHABLE_DISTANCE;
firingLineSummary.IndexOfNextFiringLinePoint = -1;
return;
}
Node firingLineNode = new Node(ActionType.FiringLine, movementDir, firingDist.StartingTankPosition,
(byte)nextFiringLineIndex, edgeOffset);
bfsQueue.Add(firingLineNode, nextEdgeWeighting);
}
if (nextFiringLineIndex == firingLine.Length)
{
firingLineSummary.NextEdgeWeighting = Constants.UNREACHABLE_DISTANCE;
firingLineSummary.IndexOfNextFiringLinePoint = -1;
}
}
private bool TryInitializeFiringLinesAndAddInitialFiringLineNodesToQueue(
Cell target, TwoValuedCircularBuffer <Node> bfsQueue,
FiringLineSummary[,] firingLineSummariesByMovementDirAndEdgeOffset)
{
bool areFiringLinesStillActive = false;
foreach (Direction movementDir in MovementDirections)
{
foreach (EdgeOffset edgeOffset in EdgeOffsets)
{
Line <FiringDistance> firingLine = FiringLineMatrix[target.Position, movementDir.GetOpposite(), edgeOffset];
FiringLineSummary firingLineSummary = new FiringLineSummary
{
FiringLine = firingLine
};
firingLineSummariesByMovementDirAndEdgeOffset[(int)movementDir, (int)edgeOffset] = firingLineSummary;
if (firingLine.Length == 0)
{
firingLineSummary.IndexOfNextFiringLinePoint = -1;
firingLineSummary.NextEdgeWeighting = Constants.UNREACHABLE_DISTANCE;
}
else
{
areFiringLinesStillActive = true;
firingLineSummary.IndexOfNextFiringLinePoint = 0;
firingLineSummary.NextEdgeWeighting = firingLine[0].TicksTillTargetShot - 1;
// Note that we add these initial firing line nodes with a distance of zero.
// This is because we need an edge of length 1 from the movement node at the tank's position to the firing line node.
// So we have to subtract 1 from the firing line node's own distance to compensate for this.
// Add the firing line points to the queue:
if (firingLineSummary.NextEdgeWeighting == 0)
{
AddNextFiringLineNodesToQueueForMovementDirAndEdgeOffset(bfsQueue,
movementDir, edgeOffset, firingLineSummary, distanceToAdd: 0);
}
}
}
}
return(areFiringLinesStillActive);
}
private bool TryAddNextFiringLineNodesToQueue(
TwoValuedCircularBuffer <Node> bfsQueue, FiringLineSummary[,] firingLineSummariesByMovementDirAndEdgeOffset,
int distanceToAdd)
{
bool anyAdded = false;
foreach (Direction movementDir in MovementDirections)
{
foreach (EdgeOffset edgeOffset in EdgeOffsets)
{
FiringLineSummary firingLineSummary
= firingLineSummariesByMovementDirAndEdgeOffset[(int)movementDir, (int)edgeOffset];
if (firingLineSummary.NextEdgeWeighting == distanceToAdd && firingLineSummary.IndexOfNextFiringLinePoint >= 0)
{
AddNextFiringLineNodesToQueueForMovementDirAndEdgeOffset(
bfsQueue, movementDir, edgeOffset, firingLineSummary, distanceToAdd);
anyAdded = true;
}
}
}
return(anyAdded);
}
public DirectionalMatrix <DistanceCalculation> CalculateMatrixOfShortestDistancesToTargetCell(Cell target)
{
if (MovementDirections == null)
{
MovementDirections = BoardHelper.AllRealDirections;
}
if (EdgeOffsets == null)
{
EdgeOffsets = FiringLineMatrix.EdgeOffsets;
}
BitMatrix walls = GameStateCalculationCache.GameState.Walls;
DirectionalMatrix <DistanceCalculation> attackMatrix
= new DirectionalMatrix <DistanceCalculation>(walls.Width, walls.Height);
TwoValuedCircularBuffer <Node> bfsQueue = new TwoValuedCircularBuffer <Node>(CircularBufferCapacityRequired);
// Note: the target point will not have a distance, since it will be shot, not moved to:
TankLocation tankLocationAtTargetPoint = TurnCalculationCache.TankLocationMatrix[target.Position];
if ((TargetElementType == ElementType.BASE) || (TargetElementType == ElementType.BULLET && AllowDestroyingABulletByMovingIntoIt))
{
AddNodesToQueueForMovingOverTarget(attackMatrix, bfsQueue, tankLocationAtTargetPoint);
}
else
if (TargetElementType == ElementType.TANK)
{
// TODO: Make points taboo if they would lead to both tank bodies overlapping, or moving directly in front of an enemy tank
/* TODO: a. Is this needed? Won't it break some algorithms?
* b. Check that points are in the board area
* foreach (Point point in tankLocationAtTargetPoint.TankHalo.GetPoints())
* {
* foreach (Direction dir in BoardHelper.AllRealDirections)
* {
* attackMatrix[dir, point.X, point.Y] = new DistanceCalculation(-1, new Node());
* }
* }
*/
}
else
{
// Bullet that can't be moved into...
// TODO: Make points taboo within the "outline" of a tank body centred on the bullet
}
if (TabooAreas != null)
{
foreach (Rectangle rect in TabooAreas)
{
foreach (Point point in rect.GetPoints())
{
foreach (Direction dir in BoardHelper.AllRealDirections)
{
if (TurnCalculationCache.CellMatrix[point].IsValid)
{
attackMatrix[dir, point.X, point.Y] = new DistanceCalculation(TABOO_DISTANCE, new Node());
}
}
}
}
}
// Use the firing distance calculations for the target point, and add the initial points to the BFS queue:
FiringLineSummary[,] firingLineSummariesByMovementDirAndEdgeOffset
= new FiringLineSummary[Constants.RELEVANT_DIRECTION_COUNT, Constants.EDGE_OFFSET_COUNT];
bool areFiringLinesStillActive = TryInitializeFiringLinesAndAddInitialFiringLineNodesToQueue(
target, bfsQueue, firingLineSummariesByMovementDirAndEdgeOffset);
int currDistance = 0;
while (true)
{
if (areFiringLinesStillActive && bfsQueue.Size == 0)
{
// Get nodes from the firing line/s with the next shortest distance:
areFiringLinesStillActive = TryAddFiringLineNodesWithNextShortestDistance(
bfsQueue, firingLineSummariesByMovementDirAndEdgeOffset, out currDistance);
}
if (bfsQueue.Size == 0)
{
break;
}
CircularBufferItem <Node> bufferItem = bfsQueue.Remove();
Node currNode = bufferItem.Item;
if (bufferItem.Value > currDistance)
{
if (bufferItem.Value == Constants.UNREACHABLE_DISTANCE)
{
break;
}
currDistance = bufferItem.Value;
// Add firing line nodes with the new distance to the queue:
if (areFiringLinesStillActive)
{
areFiringLinesStillActive = TryAddNextFiringLineNodesToQueue(bfsQueue,
firingLineSummariesByMovementDirAndEdgeOffset, currDistance);
}
}
int adjDistance = currDistance + 1;
// Get each node adjacent to the current node:
SegmentState innerEdgeStateInNodeDir = GameStateCalculationCache.TankInnerEdgeMatrix[currNode.X, currNode.Y][(int)currNode.Dir];
SegmentState[] outerEdgeStates = GameStateCalculationCache.TankOuterEdgeMatrix[currNode.X, currNode.Y];
SegmentState outerEdgeStateInNodeDir = outerEdgeStates[(int)currNode.Dir];
#if CONDITIONAL_BREAKPOINT_AttackTargetDistanceCalculator_CalculateMatrixOfShortestDistancesToTargetCell
System.Diagnostics.Debug.Assert(currNode.X != 39 || currNode.Y != 45 || currNode.Dir != Direction.UP, "Breakpoint");
#endif
// Node[] adjacentNodes = currNode.GetAdjacentIncomingNodes(innerEdgeStateInNodeDir, outerEdgeStateInNodeDir, outerEdgeStateInOppositeDir);
// Insert inline for better performance...
// **********************
Node[] adjacentNodes = new Node[MAX_POSSIBLE_PRECEDING_NODE_COUNT];
byte adjacentNodeCount = 0;
if (currNode.ActionType == ActionType.FiringLine || currNode.ActionType == ActionType.Firing)
{
// Firing and/or the firing line can only be invoked if the tank is first facing in the correct direction:
Node positioningNode = new Node(ActionType.Moving, currNode.Dir /*movementDir*/, currNode.X, currNode.Y);
adjacentNodes[0] = positioningNode;
adjacentNodeCount = 1;
}
else
{
// So now the destination node (this) must be a moving node in the given direction...
Node adjacentNode;
// If there is a blocking wall in its direction of movement,
// then any of the other movement/positioning nodes on the same cell
// can be a preceding node on the path:
if (outerEdgeStateInNodeDir == SegmentState.ShootableWall || outerEdgeStateInNodeDir == SegmentState.UnshootablePartialWall)
{
foreach (Direction otherDir in BoardHelper.AllRealDirections)
{
if (otherDir != currNode.Dir)
{
adjacentNode = new Node(ActionType.Moving, otherDir, currNode.X, currNode.Y);
adjacentNodes[adjacentNodeCount] = adjacentNode;
adjacentNodeCount++;
}
}
}
// Ignore invalid prior cells:
if (outerEdgeStates[(int)(currNode.Dir.GetOpposite())] != SegmentState.OutOfBounds)
{
// Get the adjacent cell's position:
int newX = currNode.X;
int newY = currNode.Y;
switch (currNode.Dir)
{
case Direction.UP:
newY++;
break;
case Direction.DOWN:
newY--;
break;
case Direction.LEFT:
newX++;
break;
case Direction.RIGHT:
newX--;
break;
}
switch (innerEdgeStateInNodeDir)
{
case SegmentState.Clear:
// Add all 4 directions on the adjacent cell
foreach (Direction otherDir in BoardHelper.AllRealDirections)
{
adjacentNode = new Node(ActionType.Moving, otherDir, newX, newY);
adjacentNodes[adjacentNodeCount] = adjacentNode;
adjacentNodeCount++;
}
break;
case SegmentState.ShootableWall:
// Add the firing node in the current direction on the adjacent cell:
adjacentNode = new Node(ActionType.Firing, currNode.Dir, newX, newY);
adjacentNodes[adjacentNodeCount] = adjacentNode;
adjacentNodeCount++;
break;
}
}
}
// **********************
// End of inlined section
for (int n = 0; n < adjacentNodeCount; n++)
{
Node adj = adjacentNodes[n];
// Note: adj will never be a firing line node, as they are not incoming nodes for any other node type.
if (adj.ActionType == ActionType.Moving)
{
// Check if the node already has a distance i.e. has it already been expanded?
if (attackMatrix[adj.Dir, adj.X, adj.Y].CodedDistance == 0)
{
// Set the new shortest distance:
attackMatrix[adj.Dir, adj.X, adj.Y] = new DistanceCalculation(adjDistance, currNode);
// Add to the queue to be expanded:
bfsQueue.Add(adj, adjDistance);
}
}
else
{
// It would be useful to have the firing nodes as well, as a tank could currently be firing.
// However this will double the storage requirements.
// Rather just do quick calculations to estimate the distance.
// For example:
// 1. Get the shortest distance from the current node.
// 2. If firing is on the shortest distance from the current node, then subtract 1 from the distance (since it's already firing).
// 3. If it's not on the shortest distance (but it still might be a shortest path, due to multiple equal paths),
// then get one plus the shortest distance from the adjacent node in the firing direction.
// a. If this is less than the shortest distance, use it as the shortest distance.
// b. Otherwise use the shortest distance path instead (don't make use of the space fired at).
bfsQueue.Add(adj, adjDistance);
}
}
}
return(attackMatrix);
}
