void TrianglePlaneRelations(ref Triangle3d triangle, ref Plane3d plane,
out Vector3D distance, out Index3i sign, out int positive, out int negative, out int zero)
{
// Compute the signed distances of triangle vertices to the plane. Use
// an epsilon-thick plane test.
positive = 0;
negative = 0;
zero = 0;
distance = Vector3D.Zero;
sign = Index3i.Zero;
for (int i = 0; i < 3; ++i)
{
distance[i] = plane.DistanceTo(triangle[i]);
if (distance[i] > math.MathUtil.ZeroTolerance)
{
sign[i] = 1;
positive++;
}
else if (distance[i] < -math.MathUtil.ZeroTolerance)
{
sign[i] = -1;
negative++;
}
else
{
distance[i] = (double)0;
sign[i] = 0;
zero++;
}
}
}
// Test-intersection query.
public bool Test()
{
Vector3d P0 = segment.P0;
var sdistance0 = plane.DistanceTo(P0);
if (Math.Abs(sdistance0) <= MathUtil.ZeroTolerance)
{
sdistance0 = 0;
}
var P1 = segment.P1;
var sdistance1 = plane.DistanceTo(P1);
if (Math.Abs(sdistance1) <= MathUtil.ZeroTolerance)
{
sdistance1 = 0;
}
var prod = sdistance0 * sdistance1;
if (prod < 0)
{
// The segment passes through the plane.
Type = IntersectionType.Point;
return(true);
}
if (prod > 0)
{
// The segment is on one side of the plane.
Type = IntersectionType.Empty;
return(false);
}
if (sdistance0 != 0 || sdistance1 != 0)
{
// A segment end point touches the plane.
Type = IntersectionType.Point;
return(true);
}
// The segment is coincident with the plane.
Type = IntersectionType.Segment;
return(true);
}
// Test-intersection query.
public bool Test()
{
var DdN = line.Direction.Dot(plane.Normal);
if (Math.Abs(DdN) > MathUtil.ZeroTolerance)
{
// The line is not parallel to the plane, so they must intersect.
// The line parameter is *not* set, since this is a test-intersection
// query.
Type = IntersectionType.Point;
return true;
}
// The line and plane are parallel. Determine if they are numerically
// close enough to be coincident.
var signedDistance = plane.DistanceTo(line.Origin);
if (Math.Abs(signedDistance) <= MathUtil.ZeroTolerance)
{
Type = IntersectionType.Line;
return true;
}
Type = IntersectionType.Empty;
return false;
}
