Segment de la ligne et le Cercle d'Intersection

À faire que d'abord trouver les points d'intersection avec le cercle, et de prendre le plus proche de la ligne de point de départ

Afin de Vérifier ce code

//cx,cy est le centre du cercle

        public PointF ClosestIntersection(float cx, float cy, float radius,
PointF lineStart, PointF lineEnd)
{
PointF intersection1;
PointF intersection2;
int intersections = FindLineCircleIntersections(cx, cy, radius, lineStart, lineEnd, out intersection1, out intersection2);
if (intersections == 1)
return intersection1;//one intersection
if (intersections == 2)
{
double dist1 = Distance(intersection1, lineStart);
double dist2 = Distance(intersection2, lineStart);
if (dist1 < dist2)
return intersection1;
else
return intersection2;
}
return PointF.Empty;//no intersections at all
}
private double Distance(PointF p1, PointF p2)
{
return Math.Sqrt(Math.Pow(p2.X - p1.X, 2) + Math.Pow(p2.Y - p1.Y, 2));
}
//Find the points of intersection.
private int FindLineCircleIntersections(float cx, float cy, float radius,
PointF point1, PointF point2, out PointF intersection1, out PointF intersection2)
{
float dx, dy, A, B, C, det, t;
dx = point2.X - point1.X;
dy = point2.Y - point1.Y;
A = dx * dx + dy * dy;
B = 2 * (dx * (point1.X - cx) + dy * (point1.Y - cy));
C = (point1.X - cx) * (point1.X - cx) + (point1.Y - cy) * (point1.Y - cy) - radius * radius;
det = B * B - 4 * A * C;
if ((A <= 0.0000001) || (det < 0))
{
//No real solutions.
intersection1 = new PointF(float.NaN, float.NaN);
intersection2 = new PointF(float.NaN, float.NaN);
return 0;
}
else if (det == 0)
{
//One solution.
t = -B / (2 * A);
intersection1 = new PointF(point1.X + t * dx, point1.Y + t * dy);
intersection2 = new PointF(float.NaN, float.NaN);
return 1;
}
else
{
//Two solutions.
t = (float)((-B + Math.Sqrt(det)) / (2 * A));
intersection1 = new PointF(point1.X + t * dx, point1.Y + t * dy);
t = (float)((-B - Math.Sqrt(det)) / (2 * A));
intersection2 = new PointF(point1.X + t * dx, point1.Y + t * dy);
return 2;
}
}

Intersection forme de Code ici LIEN

OriginalL'auteur yazan