public Intersections Filter(Intersections xs)
{
// begin outside of both children
bool inLeft = false;
bool inRight = false;
// prepare a list to receive the filtered intersections
var result = new Intersections();
foreach (var intersection in xs)
{
// if i.object is part of the "left" child, then lhit is true
bool leftHit = Left.Contains(intersection.Object);
if (IntersectionAllowed(leftHit, inLeft, inRight))
{
result.Add(intersection);
}
// depending on which object was hit, toggle either inl or inr
if (leftHit)
{
inLeft = !inLeft;
}
else
{
inRight = !inRight;
}
}
result.Sort();
return(result);
}
public override Intersections IntersectLocal(Ray ray)
{
var xs = new Intersections();
var a = ray.Direction.X * ray.Direction.X - ray.Direction.Y * ray.Direction.Y + ray.Direction.Z * ray.Direction.Z;
var b = 2 * ray.Origin.X * ray.Direction.X - 2 * ray.Origin.Y * ray.Direction.Y + 2 * ray.Origin.Z * ray.Direction.Z;
var c = ray.Origin.X * ray.Origin.X - ray.Origin.Y * ray.Origin.Y + ray.Origin.Z * ray.Origin.Z;
if (Math.Abs(a) <= double.Epsilon && Math.Abs(b) > double.Epsilon)
{
var t = -c / (2 * b);
xs.Add(new Intersection(t, this));
}
if (Math.Abs(a) > double.Epsilon)
{
var disc = b * b - 4 * a * c;
if (disc >= 0)
{
var t0 = (-b - Math.Sqrt(disc)) / (2 * a);
var t1 = (-b + Math.Sqrt(disc)) / (2 * a);
if (t0 > t1)
{
var tmp = t0;
t0 = t1;
t1 = tmp;
}
var y0 = ray.Origin.Y + t0 * ray.Direction.Y;
if (Minimum < y0 && y0 < Maximum)
{
xs.Add(new Intersection(t0, this));
}
var y1 = ray.Origin.Y + t1 * ray.Direction.Y;
if (Minimum < y1 && y1 < Maximum)
{
xs.Add(new Intersection(t1, this));
}
}
}
IntersectCaps(ray, xs);
xs.Sort();
return(xs);
}
public override Intersections IntersectLocal(Ray ray)
{
var xs = new Intersections();
var a = ray.Direction.X * ray.Direction.X + ray.Direction.Z * ray.Direction.Z;
// ray is not parallel to the y axis
if (a > double.Epsilon)
{
var b = 2 * ray.Origin.X * ray.Direction.X + 2 * ray.Origin.Z * ray.Direction.Z;
var c = ray.Origin.X * ray.Origin.X + ray.Origin.Z * ray.Origin.Z - 1;
var disc = b * b - 4 * a * c;
// ray does not intersect the cylinder
if (disc < 0)
{
return(xs);
}
var t0 = (-b - Math.Sqrt(disc)) / (2 * a);
var t1 = (-b + Math.Sqrt(disc)) / (2 * a);
if (t0 > t1)
{
var t = t0;
t0 = t1;
t1 = t;
}
var y0 = ray.Origin.Y + t0 * ray.Direction.Y;
if (Minimum < y0 && y0 < Maximum)
{
xs.Add(new Intersection(t0, this));
}
var y1 = ray.Origin.Y + t1 * ray.Direction.Y;
if (Minimum < y1 && y1 < Maximum)
{
xs.Add(new Intersection(t1, this));
}
}
IntersectCaps(ray, xs);
xs.Sort();
return(xs);
}
public void IntersectingRayWithNonEmptyGroupTest()
{
var g = new Group();
var s1 = Helper.Sphere();
var s2 = Helper.Sphere().Translate(tz: -3);
var s3 = Helper.Sphere().Translate(tx: 5);
g.Add(s1, s2, s3);
var r = Helper.Ray(0, 0, -5, 0, 0, 1);
var xs = new Intersections();
g.IntersectLocal(ref r.Origin, ref r.Direction, xs);
xs.Sort();
Check.That(xs).CountIs(4);
Check.That(xs[0].Object).IsSameReferenceAs(s2);
Check.That(xs[1].Object).IsSameReferenceAs(s2);
Check.That(xs[2].Object).IsSameReferenceAs(s1);
Check.That(xs[3].Object).IsSameReferenceAs(s1);
}