public static bool intersection(Segment seg1, Segment seg2)
{
Coordinates dir1 = seg1.end - seg1.beg;
Coordinates dir2 = seg2.end - seg2.beg;
//считаем уравнения прямых проходящих через отрезки
float a1 = -dir1.y;
float b1 = +dir1.x;
float d1 = -(a1 * seg1.beg.x + b1 * seg1.beg.y);
float a2 = -dir2.y;
float b2 = +dir2.x;
float d2 = -(a2 * seg2.beg.x + b2 * seg2.beg.y);
//подставляем концы отрезков, для выяснения в каких полуплоскотях они
float seg1_line2_start = a2 * seg1.beg.x + b2 * seg1.beg.y + d2;
float seg1_line2_end = a2 * seg1.end.x + b2 * seg1.end.y + d2;
float seg2_line1_start = a1 * seg2.beg.x + b1 * seg2.beg.y + d1;
float seg2_line1_end = a1 * seg2.end.x + b1 * seg2.end.y + d1;
if (lit(seg1_line2_end) || lit(seg1_line2_start) ||
lit(seg2_line1_end) || lit(seg2_line1_start))
{
return true;
}
//если концы одного отрезка имеют один знак, значит он в одной полуплоскости и пересечения нет.
if (seg1_line2_start * seg1_line2_end >= 0 || seg2_line1_start * seg2_line1_end >= 0)
{
return false;
}
return true;
}
public static bool segmentCircleIntersection(Segment seg, Coordinates center, float radius, ref Coordinates a, ref Coordinates b)
{
bool rez = false;
//shift segment
Segment newSeg = seg;
newSeg.beg = newSeg.beg - center;
newSeg.end = newSeg.end - center;
//vector
Coordinates newC = seg.end - seg.beg;
if (Math.Abs(newC.x) < float.Epsilon)
{
rez = segCirInt(1f, 0f, newSeg.beg.x, radius, ref a, ref b);
}
else
{
newC.x = newC.y/newC.x;
newC.y = (-1.0f);
float C = -(newC.x * newSeg.beg.x + newC.y * newSeg.beg.y);
rez = segCirInt(newC.x, newC.y,C, radius,ref a, ref b);
}
if (rez)
{
a = a + center;
b = b + center;
}
return rez;
}
public Wall(Segment seg_, WallType type_)
{
seg = seg_;
type = type_;
}
public bool intersects(Segment seg)
{
Coordinates a = beg, b = end, c = seg.beg, d = seg.end;
return intersect1(a.x, b.x, c.x, d.x)
&& intersect1(a.y, b.y, c.y, d.y)
&& Coordinates.area(a, b, c) * Coordinates.area(a, b, d) <= float.Epsilon
&& Coordinates.area(c, d, a) * Coordinates.area(c, d, b) <= float.Epsilon;
}
public static bool intersection2(Segment seg1, Segment seg2)
{
return seg1.intersects(seg2);
}
public void addCommonWall(Segment seg)
{
list.Add(genNewKey(), new Wall(seg, WallType.Common_Wall));
}
public List<Wall> wallsAroundPoint(Coordinates center, float radius)
{
List<Wall> rez = new List<Wall>();
Coordinates a = new Coordinates();
Coordinates b = new Coordinates();
Segment deleteThis = new Segment();
foreach (Wall wall in list.Values)
{
if (segmentCircleIntersection(wall.seg, center, radius, ref a, ref b))
{
//rez.Add(new Wall(middleSeg(wall.seg.beg, wall.seg.end, a,b), wall.type));
deleteThis = middleSeg(wall.seg.beg, wall.seg.end, a, b);
rez.Add(new Wall(deleteThis,wall.type));
//Console.WriteLine("So");
//Console.WriteLine("Center: " + center.ToString() + ", Radius =" + radius.ToString());
//Console.WriteLine("Wall:" + wall.seg.ToString());
//Console.WriteLine("Result:" +);
}
}
return rez;
}
public bool haveIntersections(Segment path)
{
foreach (Wall wallStruct in list.Values) {
if (wallStruct.type == WallType.Common_Wall &&
Segment.intersection(path,wallStruct.seg))
{
return true;
}
}
return false;
}
public void addWall(Segment seg)
{
wallList.addCommonWall(seg);
}