public Extent2D CircumCircleExtent()
{
if (m_circumCircleExtent == null)
{
m_circumCircleExtent = DelaunayGeometry.Circumcircle(m_v[0], m_v[1], m_v[2], centroidX, centroidY);
}
return(m_circumCircleExtent);
}
private void ForceClockwise()
{
if (DelaunayGeometry.CrossProduct(m_v[0], m_v[1], m_v[2]) >= 0)
{
// a positive value indicates counter clockwise
// Swapping the first 2 points should be enough
DelaunayPoint tmp = m_v[0];
m_v[0] = m_v[1];
m_v[1] = tmp;
}
}
public bool Contains(DelaunayPoint p)
{
// Only bother to check if the point is within the initial extents of the Triangle_t
if (m_extent.Contains(p.X, p.Y, true))
{
return(
(DelaunayGeometry.CrossProduct(m_v[0], p, m_v[1]) >= 0.0) &&
(DelaunayGeometry.CrossProduct(m_v[1], p, m_v[2]) >= 0.0) &&
(DelaunayGeometry.CrossProduct(m_v[2], p, m_v[0]) >= 0.0));
}
return(false);
}
bool Overlaps(Extent2D extent)
{
// Check simplist case - triangle inside extent.
if (extent.Contains(m_extent))
{
return(true);
}
// Use right-hand rule for each triangle segment against all points of extent rectangle.
DelaunayPoint p1 = new DelaunayPoint(extent.MinX, extent.MinY, 0.0f, 0);
DelaunayPoint p2 = new DelaunayPoint(extent.MaxX, extent.MinY, 0.0f, 0);
DelaunayPoint p3 = new DelaunayPoint(extent.MaxX, extent.MaxY, 0.0f, 0);
DelaunayPoint p4 = new DelaunayPoint(extent.MinX, extent.MaxY, 0.0f, 0);
int ar = 0;
if (DelaunayGeometry.CrossProduct(m_v[0], p1, m_v[1]) >= 0.0f)
{
++ar;
}
if (DelaunayGeometry.CrossProduct(m_v[0], p2, m_v[1]) >= 0.0f)
{
++ar;
}
if (DelaunayGeometry.CrossProduct(m_v[0], p3, m_v[1]) >= 0.0f)
{
++ar;
}
if (DelaunayGeometry.CrossProduct(m_v[0], p4, m_v[1]) >= 0.0f)
{
++ar;
}
int br = 0;
if (DelaunayGeometry.CrossProduct(m_v[1], p1, m_v[2]) >= 0.0f)
{
++br;
}
if (DelaunayGeometry.CrossProduct(m_v[1], p2, m_v[2]) >= 0.0f)
{
++br;
}
if (DelaunayGeometry.CrossProduct(m_v[1], p3, m_v[2]) >= 0.0f)
{
++br;
}
if (DelaunayGeometry.CrossProduct(m_v[1], p4, m_v[2]) >= 0.0f)
{
++br;
}
int cr = 0;
if (DelaunayGeometry.CrossProduct(m_v[2], p1, m_v[0]) >= 0.0f)
{
++cr;
}
if (DelaunayGeometry.CrossProduct(m_v[2], p2, m_v[0]) >= 0.0f)
{
++cr;
}
if (DelaunayGeometry.CrossProduct(m_v[2], p3, m_v[0]) >= 0.0f)
{
++cr;
}
if (DelaunayGeometry.CrossProduct(m_v[2], p4, m_v[0]) >= 0.0f)
{
++cr;
}
// There will be some sort intersection of triangle with rectangle if at least one point of
// the rectangle is on, or to the right (not zero) of every segment of the triangle.
if (ar != 0 && br != 0 && cr != 0)
{
return(true);
}
return(false);
}