public static bool SegmentTest(Vector a, Vector b, Vector c, Vector d)
{
double triaa = JMath.SignedTriangleArea(a, b, d);
double triab = JMath.SignedTriangleArea(a, b, c);
double triac = 0;
double triad = 0;
//notice here it is "<=" not "<"
if (triaa * triab <= 0.0)
{
triac = JMath.SignedTriangleArea(c, d, a);
triad = triac + triab - triaa;
if (triac * triad <= 0.0)
{
return(true);
}
}
if (triaa + triab + triac + triad == 0.0)
{
Vector ab = b - a;
double abdab = Dot(ab, ab);
Vector ac = c - a;
double abdac = Dot(ab, ac);
Vector ad = d - a;
double abdad = Dot(ab, ad);
double min = Math.Min(abdac, abdad);
double max = Math.Max(abdac, abdad);
return(min < abdab && max > 0);
}
return(false);
}
public static bool PointInPolygon(Vertex[] vs, Vector pt, Vector infinity)
{
uint count = 0;
uint i = 0;
while (i < vs.Length - 1)
{
if (JMath.SegmentTest(pt, infinity, vs[i].Position, vs[i + 1].Position))
{
++count;
}
++i;
}
if (JMath.SegmentTest(pt, infinity, vs[i].Position, vs[0].Position))
{
++count;
}
return((count & 1) == 1);
}
public static double AngleDeg(Vector va, Vector vb)
{
return(JMath.AngleRad(va, vb) / Math.PI * 180.0);
}
/*
* a*b=|a|*|b|*cos angle
* cos angle=a*b/(|a|*|b|)
* angle = arccos (a*b/(|a|*|b|))
*/
public static double AngleRad(Vector va, Vector vb)
{
return(Math.Acos(JMath.Dot(va, vb) / (va.Length + vb.Length)));
}
