public static bool Test(LineSegment seg, Vector3 a, Vector3 b, Vector3 c, out float u, out float v, out float w)
{
Vector3 ab = b - a;
Vector3 ac = c - a;
Vector3 qp = seg.Point1 - seg.Point2;
// Compute triangle normal. Can be precalculated or cached if
// intersecting multiple segments against the same triangle
Vector3 n = Vector3.Cross(ab, ac);
// Compute denominator d. If d <= 0, segment is parallel to or points
// away from triangle, so exit early
float d = Vector3.Dot(qp, n);
if (d <= 0.0f)
{
u = 0; v = 0; w = 0;
return false;
}
// Compute intersection t value of pq with plane of triangle. A ray
// intersects iff 0 <= t. Segment intersects iff 0 <= t <= 1. Delay
// dividing by d until intersection has been found to pierce triangle
Vector3 ap = seg.Point1 - a;
float t = Vector3.Dot(ap, n);
if (t < 0.0f)
{
u = 0; v = 0; w = 0;
return false;
}
if (t > d)
{
u = 0; v = 0; w = 0;
return false; // For segment; exclude this code line for a ray test
}
// Compute barycentric coordinate components and test if within bounds
Vector3 e = Vector3.Cross(qp, ap);
v = Vector3.Dot(ac, e);
if (v < 0.0f || v > d)
{
u = 0; w = 0;
return false;
}
w = -Vector3.Dot(ab, e);
if (w < 0.0f || v + w > d)
{
u = 0;
return false;
}
// Segment/ray intersects triangle. Perform delayed division and
// compute the last barycentric coordinate component
float ood = 1.0f / d;
t *= ood;
v *= ood;
w *= ood;
u = 1.0f - v - w;
return true;
}
public override bool Test(LineSegment other)
{
// TODO
throw new NotImplementedException();
}
public static bool Test(LineSegment seg, BoundingSphere sphere)
{
ContainmentType ct1 = sphere.Contains(seg.Point1);
ContainmentType ct2 = sphere.Contains(seg.Point2);
return ct1 != ct2;
}
public static bool Test(LineSegment seg, Plane plane)
{
Vector3 q;
float t;
// Compute the t value for the directed line ab intersecting the plane
Vector3 ab = seg.Point2 - seg.Point1;
t = (plane.D - Vector3.Dot(plane.Normal, seg.Point1)) / Vector3.Dot(plane.Normal, ab);
// If t in [0..1] compute and return intersection point
if (t >= 0.0f && t <= 1.0f)
{
q = seg.Point1 + t * ab;
return true;
}
// Else no intersection
return false;
}
public static bool Test(LineSegment seg, AxisAlignedBoundingBox bb)
{
Vector3 c = (bb.Min + bb.Max) * 0.5f; // box center point
Vector3 e = bb.Max - c; // box halflength extents
Vector3 m = (seg.Point1 + seg.Point2) * 0.5f; // segment midpoint
Vector3 d = seg.Point1 - m; // segment halflength vector
m = m - c; // translate box and segment to origin
// try world coordinate axes as seperating axes
float adx = Math.Abs(d.X);
if (Math.Abs(m.X) > e.X + adx)
return false;
float ady = Math.Abs(d.Y);
if (Math.Abs(m.Y) > e.Y + ady)
return false;
float adz = Math.Abs(d.Z);
if (Math.Abs(m.Z) > e.Z + adz)
return false;
// add in an epsilon term to counteract arithmetic errors when segment is (near) parallel to a coordinate axis
adx += FPPrecisionHelper.EPSILON; ady += FPPrecisionHelper.EPSILON; adz += FPPrecisionHelper.EPSILON;
// try cross products of segment direction vector with coordinate axes
if (Math.Abs(m.Y * d.Z - m.Z * d.Y) > e.Y * adz + e.Z * ady)
return false;
if (Math.Abs(m.Z * d.X - m.X * d.Z) > e.X * adz + e.Z * adx)
return false;
if (Math.Abs(m.X * d.Y - m.Y * d.X) > e.X * ady + e.Y * adx)
return false;
// no separating axis found; segment must be overlapping AABB
return true;
}
public static bool Test(LineSegment seg, BoundingFrustum frus)
{
ContainmentType ct1 = frus.Contains(seg.Point1);
ContainmentType ct2 = frus.Contains(seg.Point2);
return ct1 != ct2;
}
public abstract bool Test(LineSegment other);
public abstract bool Test(LineSegment other);
public override bool Test(LineSegment other)
{
return IntersectionTests.Test(other, this);
}
public override bool Test(LineSegment other)
{
return(IntersectionTests.Test(other, this));
}
public override bool Test(LineSegment other)
{
// TODO
throw new NotImplementedException();
}
