public bool DoesSegmentCrossContour(Vector2 segmentStart, Vector2 segmentEnd, ReadOnlyCollection <Vector2> contour)
{
if (contour == null)
{
throw new ArgumentNullException("contour");
}
else if (contour.Count < 2)
{
throw new ArgumentException("contour has less than two points, and is therefore invalid");
}
for (int i = 0; i < contour.Count - 1; i++)
{
Vector2 dummy;
if (Geometry2D.AreLineSegmentsCrossing(segmentStart, segmentEnd, out dummy, contour[i], contour[i + 1], out dummy))
{
return(true);
}
}
return(false);
}
/*
* There are a handful of possible cases for this method.
*
* In the first case, CenterLeftContour and CenterRightContour intersect each-other.
* In that case, we want to remove all of the points in each contour beyond the other
* and then join them at the intersect. We do this by checking the contours in opposite
* directions. Because all contours are oriented clockwise around their cell, if we
* check for line segment collision carefully we'll know exactly which points need to
* be removed. Any intersection will appear close to the beginning of CenterRightContour
* and the end of CenterLeftContour. Thus we work up CenterRightContour and down
* CenterLeftContour. Once we find an intersection, we strip points from the beginning of
* CenterRightContour and the end of CenterLeftContour and add the intersection point at
* the beginning and end, respectively.
*
* In the second case, CenterLeftContour doesn't touch CenterRightContour but CenterRightContour
* extends undesirably into the rivers. To handle this, we extrapolate forward from
* CenterLeftContour using its last and second to last points, check for an intersection,
* and then cull points and add the intersection as above.
*
* In the third case, CenterRightContour doesn't touch CenterLeftContour but CenterLeftContour
* extends undesirably into the rivers. We handle this much the same way, extrapolating
* backwards from the first and second points of CenterRightContour, checking for an intersecton,
* and culling as needed.
*
* In the fourth case, neither contours touch each-other or extend into the rivers. In that case,
* we extrapolate on both contours (forward for CenterLeft, backward for CenterRight) and add
* their intersection without culling.
*/
public void RationalizeCellContours(
IHexCell center, HexDirection direction
)
{
List <Vector2> centerLeftContour = CellEdgeContourCanon.GetContourForCellEdge(center, direction.Previous()).ToList();
List <Vector2> centerRightContour = CellEdgeContourCanon.GetContourForCellEdge(center, direction).ToList();
int lastOutsideLeftIndex = centerLeftContour.Count - 1;
int lastOutsideRightIndex = 0;
Vector2 contourIntersect = Vector2.zero;
bool hasFoundIntersect = false;
//We multiply our extrapolating vector by some relatively large number to make it more likely
//that they intersect properly.
for (; lastOutsideLeftIndex > 0; lastOutsideLeftIndex--)
{
if (Geometry2D.AreLineSegmentsCrossing(
centerLeftContour[lastOutsideLeftIndex], centerLeftContour [lastOutsideLeftIndex - 1], out contourIntersect,
centerRightContour[0], centerRightContour[0] + (centerRightContour[0] - centerRightContour[1]) * 10, out contourIntersect
))
{
hasFoundIntersect = true;
break;
}
for (lastOutsideRightIndex = 0; lastOutsideRightIndex < centerRightContour.Count - 1; lastOutsideRightIndex++)
{
if (Geometry2D.AreLineSegmentsCrossing(
centerLeftContour [lastOutsideLeftIndex], centerLeftContour [lastOutsideLeftIndex - 1], out contourIntersect,
centerRightContour[lastOutsideRightIndex], centerRightContour[lastOutsideRightIndex + 1], out contourIntersect
))
{
hasFoundIntersect = true;
break;
}
}
if (hasFoundIntersect)
{
break;
}
}
if (!hasFoundIntersect)
{
Vector2 lastLeft = centerLeftContour.Last();
Vector2 secondLastLeft = centerLeftContour[centerLeftContour.Count - 2];
if (Geometry2D.AreLineSegmentsCrossing(
lastLeft, lastLeft + (lastLeft - secondLastLeft) * 10, out contourIntersect,
centerRightContour[0], centerRightContour[0] + (centerRightContour[0] - centerRightContour[1]) * 10, out contourIntersect
))
{
hasFoundIntersect = true;
}
for (lastOutsideRightIndex = 0; lastOutsideRightIndex < centerRightContour.Count - 1; lastOutsideRightIndex++)
{
if (Geometry2D.AreLineSegmentsCrossing(
lastLeft, lastLeft + (lastLeft - secondLastLeft) * 10, out contourIntersect,
centerRightContour[lastOutsideRightIndex], centerRightContour[lastOutsideRightIndex + 1], out contourIntersect
))
{
hasFoundIntersect = true;
break;
}
}
}
if (lastOutsideLeftIndex > 0)
{
centerLeftContour.RemoveRange(lastOutsideLeftIndex, centerLeftContour.Count - lastOutsideLeftIndex);
}
if (lastOutsideRightIndex < centerRightContour.Count - 1)
{
centerRightContour.RemoveRange(0, lastOutsideRightIndex + 1);
}
if (hasFoundIntersect)
{
centerLeftContour.Add(contourIntersect);
centerRightContour.Insert(0, contourIntersect);
}
CellEdgeContourCanon.SetContourForCellEdge(center, direction.Previous(), centerLeftContour);
CellEdgeContourCanon.SetContourForCellEdge(center, direction, centerRightContour);
}