/// <summary>
/// Given a <paramref name="center"/> point and a
/// <paramref name="jumpVector"/>, returns the point reached by moving
/// from the <paramref name="center"/> along
/// <paramref name="jumpStep"/> multiples of the
/// <paramref name="jumpVector"/>.
/// </summary>
/// <param name="center"></param>
/// <param name="jumpVector"></param>
/// <param name="jumpNumber"></param>
/// <returns></returns>
public static SolarGridPoint GetJumpPoint(
SolarGridPoint center,
Tuple <int, int> jumpVector,
int jumpStep)
{
var displacement = MultiplyVector(jumpVector, jumpStep);
var resultPoint = SolarGridPoint.GetPointAtRayVector(
center, displacement);
return(resultPoint);
}
public IList <SolarObject> GetObjectsVisibleFromPoint(
SolarGridPoint point,
HashSet <SolarGridPoint> pointsToCheck)
{
// Define a "jump vector" as a displacement from the given
// central point to another point.
// 1) For each integer n starting with 1, find all jump vectors where
// |x| + |y| = n.
// 2a) For each jump vector for a given n, move outwards from the
// central point in multiples of the given jump vector.
// 2b) If a point is encountered containing an object that hasn't
// been seen before, then mark that object as seen. Afterwards,
// mark any subsequent objects encountered as blocked.
IList <SolarObject> objectsSeen = new List <SolarObject>();
var pointsChecked = new HashSet <SolarGridPoint>();
var displacementVectorsChecked = new HashSet <Tuple <int, int> >();
var numberToCheck = pointsToCheck.Count;
int jumpNumber = 1;
while (pointsChecked.Count < numberToCheck)
{
// Get all jump vectors for this n
var jumpVectors = VectorHelper.GetJumpVectors(jumpNumber);
foreach (var jumpVector in jumpVectors)
{
int jumpStep = 1;
var displacementVector = VectorHelper.MultiplyVector(jumpVector, jumpStep);
if (displacementVectorsChecked.Contains(displacementVector))
{
continue;
}
displacementVectorsChecked.Add(displacementVector);
var currentPoint = SolarGridPoint.GetPointAtRayVector(point, displacementVector);
bool encounteredObjectAlongRay = false;
while (GetIsCoordinateInGrid(currentPoint))
{
if (pointsChecked.Contains(currentPoint))
{
continue;
}
// Check if the point contains an object
if (pointsToCheck.Contains(currentPoint))
{
if (!encounteredObjectAlongRay)
{
objectsSeen.Add(_solarObjectDictionary[currentPoint]);
encounteredObjectAlongRay = true;
}
pointsChecked.Add(currentPoint);
}
jumpStep++;
displacementVector = VectorHelper.MultiplyVector(jumpVector, jumpStep);
displacementVectorsChecked.Add(displacementVector);
currentPoint = SolarGridPoint.GetPointAtRayVector(point, displacementVector);
}
}
jumpNumber++;
}
return(objectsSeen);
}
