public static PointF FindStraightIntersection(AESegment segArea, AESegment track)
{
float xD1, yD1, xD2, yD2, xD3, yD3;
double dot, deg;
double len1, len2;
double segmentLen1, segmentLen2;
float ua, ub, div;
// calculate differences
xD1 = segArea.endPoint.X - segArea.startPoint.X;
xD2 = track.endPoint.X - track.startPoint.X;
yD1 = segArea.endPoint.Y - segArea.startPoint.Y;
yD2 = track.endPoint.Y - track.startPoint.Y;
xD3 = segArea.startPoint.X - track.startPoint.X;
yD3 = segArea.startPoint.Y - track.startPoint.Y;
// calculate the lengths of the two lines
len1 = Math.Sqrt(xD1 * xD1 + yD1 * yD1);
len2 = Math.Sqrt(xD2 * xD2 + yD2 * yD2);
// calculate angle between the two lines.
dot = (xD1 * xD2 + yD1 * yD2); // dot product
deg = dot / (len1 * len2);
// if abs(angle)==1 then the lines are parallell,
// so no intersection is possible
if (Math.Abs(deg) == 1)
{
public static PointF FindIntersection(AESegment segArea, AESegment track)
{
PointF intersection;
if (track.isCurved)
{
if ((int)(track.startPoint.X) == 45892)
{
intersection = PointF.Empty;
}
intersection = DrawUtility.FindCurveIntersection(segArea, track);
}
else
{
intersection = DrawUtility.FindStraightIntersection(segArea, track);
}
return(intersection);
}
public static double FindDistanceToSegment(PointF pt, AESegment seg, out PointF closest)
{
float dx = seg.endPoint.X - seg.startPoint.X;
float dy = seg.endPoint.Y - seg.startPoint.Y;
if ((dx == 0) && (dy == 0))
{
// It's a point not a line segment.
closest = seg.startPoint;
dx = pt.X - seg.startPoint.X;
dy = pt.Y - seg.startPoint.Y;
return(Math.Sqrt(dx * dx + dy * dy));
}
// Calculate the t that minimizes the distance.
float t = ((pt.X - seg.startPoint.X) * dx + (pt.Y - seg.startPoint.Y) * dy) / (dx * dx + dy * dy);
// See if this represents one of the segment's
// end points or a point in the middle.
if (t < 0)
{
closest = new PointF(seg.startPoint.X, seg.startPoint.Y);
dx = pt.X - seg.startPoint.X;
dy = pt.Y - seg.startPoint.Y;
}
else if (t > 1)
{
closest = new PointF(seg.endPoint.X, seg.endPoint.Y);
dx = pt.X - seg.endPoint.X;
dy = pt.Y - seg.endPoint.Y;
}
else
{
closest = new PointF(seg.startPoint.X + t * dx, seg.startPoint.Y + t * dy);
dx = pt.X - closest.X;
dy = pt.Y - closest.Y;
}
double info = Math.Sqrt(dx * dx + dy * dy);
return(info);
}
public AESegment(AESegment original)
{
startPoint = original.startPoint;
endPoint = original.endPoint;
isCurved = original.isCurved;
if (isCurved)
{
radius = original.radius;
center = original.center;
step = original.step;
angleTot = original.angleTot;
startAngle = original.startAngle;
lengthSegment = original.lengthSegment;
}
else
{
step = 0;
lengthSegment = original.lengthSegment;
}
}
// Find the point of intersection between
// the lines startPoint --> middlePoint and endPoint --> p4.
public static void FindIntersection(AESegment segArea, AESegment track,
out bool lines_intersect, out bool segments_intersect,
out PointF intersection, out PointF close_p1, out PointF close_p2)
{
// Get the segments' parameters.
float dx12 = segArea.endPoint.X - segArea.startPoint.X;
float dy12 = segArea.endPoint.Y - segArea.startPoint.Y;
float dx34 = track.endPoint.X - track.startPoint.X;
float dy34 = track.endPoint.Y - track.startPoint.Y;
// Solve for t1 and t2
float denominator = (dy12 * dx34 - dx12 * dy34);
float t1;
try
{
t1 = ((segArea.startPoint.X - track.startPoint.X) * dy34 + (track.startPoint.Y - segArea.startPoint.Y) * dx34) / denominator;
}
catch
{
// The lines are parallel (or close enough to it).
lines_intersect = false;
segments_intersect = false;
intersection = new PointF(float.NaN, float.NaN);
close_p1 = new PointF(float.NaN, float.NaN);
close_p2 = new PointF(float.NaN, float.NaN);
return;
}
lines_intersect = true;
float t2 = ((track.startPoint.X - segArea.startPoint.X) * dy12 + (segArea.startPoint.Y - track.startPoint.Y) * dx12) / -denominator;
// Find the point of intersection.
intersection = new PointF(segArea.startPoint.X + dx12 * t1, segArea.startPoint.Y + dy12 * t1);
// The segments intersect if t1 and t2 are between 0 and 1.
segments_intersect = ((t1 >= 0) && (t1 <= 1) && (t2 >= 0) && (t2 <= 1));
// Find the closest points on the segments.
if (t1 < 0)
{
t1 = 0;
}
else if (t1 > 1)
{
t1 = 1;
}
if (t2 < 0)
{
t2 = 0;
}
else if (t2 > 1)
{
t2 = 1;
}
close_p1 = new PointF(segArea.startPoint.X + dx12 * t1, segArea.startPoint.Y + dy12 * t1);
close_p2 = new PointF(track.startPoint.X + dx34 * t2, track.startPoint.Y + dy34 * t2);
}
// public domain function by Darel Rex Finley, 2006
// Determines the intersection point of the line segment defined by points A and B
// with the line segment defined by points C and D.
//
// Returns YES if the intersection point was found, and stores that point in X,Y.
// Returns NO if there is no determinable intersection point, in which case X,Y will
// be unmodified.
public static PointF FindStraightIntersection(AESegment segArea, AESegment track)
{
//double Ax, double Ay,
//double Bx, double By,
//double Cx, double Cy,
//double Dx, double Dy,
//double *X, double *Y
PointF pt = PointF.Empty;
double distAB, theCos, theSin, newX, ABpos;
double distCD, theCos2, theSin2;
double ABX, ABY, ACX, ACY, ADX, ADY;
double AX = segArea.startPoint.X;
double AY = segArea.startPoint.Y;
double CDX, CDY, angle1, angle2;
// Fail if either line segment is zero-length.
if ((segArea.startPoint.X == segArea.endPoint.X && segArea.startPoint.Y == segArea.endPoint.Y) ||
(track.startPoint.X == track.endPoint.X && track.startPoint.Y == track.endPoint.Y))
{
return(pt);
}
// Fail if the segments share an end-point.
if ((segArea.startPoint.X == track.startPoint.X && segArea.startPoint.Y == track.startPoint.Y) ||
(segArea.endPoint.X == track.startPoint.X && segArea.endPoint.Y == track.startPoint.Y) ||
(segArea.startPoint.X == track.endPoint.X && segArea.startPoint.Y == track.endPoint.Y) ||
(segArea.endPoint.X == track.endPoint.X && segArea.endPoint.Y == track.endPoint.Y))
{
return(pt);
}
// (1) Translate the system so that point A is on the origin.
ABX = segArea.endPoint.X - segArea.startPoint.X;
ABY = segArea.endPoint.Y - segArea.startPoint.Y;
ACX = track.startPoint.X - segArea.startPoint.X;
ACY = track.startPoint.Y - segArea.startPoint.Y;
ADX = track.endPoint.X - segArea.startPoint.X;
ADY = track.endPoint.Y - segArea.startPoint.Y;
CDX = track.endPoint.X - track.startPoint.X;
CDY = track.endPoint.Y - track.startPoint.Y;
// Discover the length of segment A-B.
distAB = Math.Sqrt(ABX * ABX + ABY * ABY);
distCD = Math.Sqrt(CDX * CDX + CDY * CDY); // sup
// (2) Rotate the system so that point B is on the positive X axis.
theCos = ABX / distAB;
theSin = ABY / distAB;
theCos2 = (CDX) / distCD; // sup
theSin2 = (CDY) / distCD; // sup
angle1 = Math.Acos(theCos) * 180 / Math.PI; // sup
angle2 = Math.Acos(theCos2) * 180 / Math.PI; // sup
newX = ACX * theCos + ACY * theSin;
ACY = ACY * theCos - ACX * theSin;
ACX = newX;
newX = ADX * theCos + ADY * theSin;
ADY = ADY * theCos - ADX * theSin;
ADX = newX;
if (Math.Abs(angle1 - angle2) < 5) // sup
{
return(pt); // sup
}
// Fail if segment C-D doesn't cross line A-B.
if (ACY < 0 && ADY < 0 || ACY >= 0 && ADY >= 0)
{
return(pt);
}
// (3) Discover the position of the intersection point along line A-B.
ABpos = ADX + (ACX - ADX) * ADY / (ADY - ACY);
// Fail if segment C-D crosses line A-B outside of segment A-B.
if (ABpos < 0 || ABpos > distAB)
{
return(pt);
}
// (4) Apply the discovered position to line A-B in the original coordinate system.
pt.X = (float)(AX + ABpos * theCos);
pt.Y = (float)(AY + ABpos * theSin);
if (FindDistancePoints(pt, segArea.startPoint) < 0.1 || FindDistancePoints(pt, segArea.endPoint) < 0.1)
{
return(PointF.Empty);
}
// Success.
return(pt);
}