/// <summary>
/// Calculates the direction of one line segment relative to another.
/// </summary>
public static RelativeDirection Calculate(Route route, int currentShape, Coordinate coordinate1, Coordinate coordinate2, Coordinate coordinate3)
{
var direction = new RelativeDirection();
var margin = 65.0;
var straightOn = 10.0;
var turnBack = 5.0;
var angleRandians = DirectionCalculator.Angle(coordinate1, coordinate2, coordinate3);
var angle = angleRandians.ToDegrees();
angle = angle.NormalizeDegrees();
// an inline branch is any branch between the rightmost and leftmost
bool isInlineBranch = false;
// only consider branches at the current 'shape'
int currentBranches = 0;
int startBranch = 0, endBranch = 0;
// if there are more than 2 branches, and we're NOT turning on to the rightmost or leftmost branch,
// then we're effectively continuing on an inline branch, so the directions should vary from the norm.
// first, determine how many branches are at this intersection (having the same 'shape' number)
for (int i = 0; i < route.Branches.Length; i++)
{
if (route.Branches[i].Shape == currentShape)
{
if (currentBranches == 0)
{
startBranch = endBranch = i;
}
else
{
endBranch = i;
}
// increment count
currentBranches++;
}
}
// we're only concerned if there is more than 1 branch here
if (true) // currentBranches > 1)
{
Dictionary <int, double> orderedBranches = new System.Collections.Generic.Dictionary <int, double>();
// for some reason, sometimes only 2 branches are returned even when there are 3;
// and the missing branch seems to always be the chosen path; therefore, we will
// make sure the chosen path is always in the collection so that we can make the
// right choice on the final direction
bool includesChosenPath = false;
// determine angles of each of the Branches
for (int i = startBranch; i <= endBranch; i++)
{
// additionally, there are times when one of the 'Branch' points is actually
// identical to one of the coordinate points, resulting in an angle of NaN;
// we will bypass any such 'Branch' as erroneous
if (coordinate1.Equals(route.Branches[i].Coordinate) || coordinate2.Equals(route.Branches[i].Coordinate))
{
continue;
}
// angle will use coordinate1, coordinate2, and current branch
var aRads = DirectionCalculator.Angle(coordinate1, coordinate2, route.Branches[i].Coordinate);
// additional safety check
if (aRads == float.NaN)
{
continue;
}
var aDegs = aRads.ToDegrees();
aDegs = aDegs.NormalizeDegrees();
// add to dictionary (branch index, angle)
orderedBranches.Add(i, aDegs);
// although the paths are almost always within 3 decimal places,
// it appears that occasionally the angle difference is as much as
// 4 degrees, so we will allow up to 4 degrees difference in comparison
// (it's fair to say for now that no 2 streets could be within 4 degrees)
if (System.Math.Abs(aDegs - angle) < 4.0)
{
includesChosenPath = true;
}
}
// before sorting, if chosen path is not in the dictionary, add it here
if (!includesChosenPath)
{
orderedBranches.Add(endBranch + 1, angle);
}
// now sort by branch angles to get branches in order, right to left (min angle to max angle)
var items = from pair in orderedBranches
orderby pair.Value ascending
select pair;
// iterate branches in order by angle (branch index is irrelevant at this point)
foreach (KeyValuePair <int, double> pair in items)
{
double aDegs = pair.Value;
// is this branch the current route? (having angle equal to current street angle)
if (System.Math.Abs(aDegs - angle) < 4.0)
{
// we found the branch of the route; see if it is one of the inline branches (not the first or last)
if (!(pair.Key == items.First().Key || pair.Key == items.Last().Key))
{
isInlineBranch = true;
// we can stop looking
break;
}
}
}
}
// directions as defined are valid if turning on
// to
if (angle >= 360 - turnBack || angle < turnBack) // +/- 5 deg
{
direction.Direction = RelativeDirectionEnum.TurnBack;
}
else if (angle >= turnBack && angle < 90 - margin) // 5 to 25 deg
{
direction.Direction = RelativeDirectionEnum.SharpRight;
// sharp right would imply the rightmost, so if not the rightmost, use 'Right' instead
if (isInlineBranch)
{
direction.Direction = RelativeDirectionEnum.Right;
}
}
else if (angle >= 90 - margin && angle < 90 + margin) // 25 to 155 deg
{
direction.Direction = RelativeDirectionEnum.Right;
// right would imply the rightmost, so if not the rightmost, use 'SlightlyRight' instead
if (isInlineBranch)
{
direction.Direction = RelativeDirectionEnum.SlightlyRight;
}
}
else if (angle >= 90 + margin && angle < 180 - straightOn) // 155 to 170 deg
{
direction.Direction = RelativeDirectionEnum.SlightlyRight;
}
else if (angle >= 180 - straightOn && angle < 180 + straightOn) // 170 to 190 deg
{
direction.Direction = RelativeDirectionEnum.StraightOn;
}
else if (angle >= 180 + straightOn && angle < 270 - margin) // 190 to 205 deg
{
direction.Direction = RelativeDirectionEnum.SlightlyLeft;
}
else if (angle >= 270 - margin && angle < 270 + margin) // 205 to 335 deg
{
direction.Direction = RelativeDirectionEnum.Left;
// left would imply the leftmost, so if not the leftmost, use 'SlightlyLeft' instead
if (isInlineBranch)
{
direction.Direction = RelativeDirectionEnum.SlightlyLeft;
}
}
else if (angle >= 270 + margin && angle < 360 - turnBack) // 335 to 355 deg
{
direction.Direction = RelativeDirectionEnum.SharpLeft;
// sharp left would imply the leftmost, so if not the leftmost, use 'Left' instead
if (isInlineBranch)
{
direction.Direction = RelativeDirectionEnum.Left;
}
}
direction.Angle = (float)angle;
return(direction);
}
