public override IntersectionList LocalIntersect(Ray ray)
{
var sphereToRay = ray.Origin - Vector4.CreatePosition(0, 0, 0);
var a = Vector4.Dot(ray.Direction, ray.Direction);
var b = 2 * Vector4.Dot(ray.Direction, sphereToRay);
var c = Vector4.Dot(sphereToRay, sphereToRay) - 1;
var discriminant = (b * b) - (4 * a * c);
// If the discriminant is negative, the ray misses
// and there are no intersections.
if (discriminant < 0)
{
return(IntersectionList.Empty());
}
// Otherwise, we have two intersections which we can
// solve for t using the quadratic formula.
var t1 = (-b - Math.Sqrt(discriminant)) / (2 * a);
var t2 = (-b + Math.Sqrt(discriminant)) / (2 * a);
var xs = new[]
{
new Intersection(t1, this),
new Intersection(t2, this),
};
return(IntersectionList.Create(xs));
}
public IntersectionList FilterIntersections(IntersectionList xs)
{
var inl = false;
var inr = false;
var result = new List <Intersection>();
foreach (var i in xs)
{
var lhit = this.Left.Includes(i.Object);
if (IntersectionAllowed(this.Operation, lhit, inl, inr))
{
result.Add(i);
}
if (lhit)
{
inl = !inl;
}
else
{
inr = !inr;
}
}
return(IntersectionList.Create(result.ToArray()));
}
public override IntersectionList LocalIntersect(Ray ray)
{
var dirCrossE2 = ray.Direction.Cross3(this.E2);
var det = this.E1.Dot(dirCrossE2);
if (Math.Abs(det) < Epsilon)
{
return(IntersectionList.Empty());
}
var f = 1.0 / det;
var p1ToOrigin = ray.Origin - this.P1;
var u = f * p1ToOrigin.Dot(dirCrossE2);
if (u < 0 || u > 1)
{
return(IntersectionList.Empty());
}
var originCrossE1 = p1ToOrigin.Cross3(this.E1);
var v = f * ray.Direction.Dot(originCrossE1);
if (v < 0 || (u + v) > 1)
{
return(IntersectionList.Empty());
}
var t = f * this.E2.Dot(originCrossE1);
return(IntersectionList.Create(
new Intersection(t, this)));
}
/// <summary>
/// Intersect with a predicate to select a subset
/// of shapes from the world.
/// </summary>
public IntersectionList Intersect(Ray ray, Func <Shape, bool> predicate)
{
Interlocked.Increment(ref Stats.Tests);
var xs = this.Objects
.Where(predicate)
.SelectMany(x => x.Intersect(ray))
.ToArray();
return(IntersectionList.Create(xs));
}
public override IntersectionList LocalIntersect(Ray ray)
{
var a = Math.Pow(ray.Direction.X, 2) + Math.Pow(ray.Direction.Z, 2);
// ray is parallel to the y-axis
if (Math.Abs(a) < Epsilon)
{
var caps = new List <Intersection>();
this.IntersectCaps(ray, caps);
return(IntersectionList.Create(caps.ToArray()));
}
var b =
2 * ray.Origin.X * ray.Direction.X +
2 * ray.Origin.Z * ray.Direction.Z;
var c = Math.Pow(ray.Origin.X, 2) + Math.Pow(ray.Origin.Z, 2) - 1;
var disc = b * b - 4 * a * c;
if (disc < 0)
{
return(IntersectionList.Empty());
}
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 xs = new List <Intersection>();
var y0 = ray.Origin.Y + t0 * ray.Direction.Y;
if (this.Minimum < y0 && y0 < this.Maximum)
{
xs.Add(new Intersection(t0, this));
}
var y1 = ray.Origin.Y + t1 * ray.Direction.Y;
if (this.Minimum < y1 && y1 < this.Maximum)
{
xs.Add(new Intersection(t1, this));
}
this.IntersectCaps(ray, xs);
return(IntersectionList.Create(xs.ToArray()));
}
public override IntersectionList LocalIntersect(Ray ray)
{
if (Math.Abs(ray.Direction.Y) < Epsilon)
{
return(IntersectionList.Empty());
}
var t = -ray.Origin.Y / ray.Direction.Y;
var i = new Intersection(t, this);
return(IntersectionList.Create(i));
}
public override IntersectionList LocalIntersect(Ray ray)
{
var bounds = this.GetBounds();
if (!bounds.Intersect(ray))
{
return(IntersectionList.Empty());
}
var xs = new List <Intersection>();
xs.AddRange(this.Left.Intersect(ray));
xs.AddRange(this.Right.Intersect(ray));
return(this.FilterIntersections(
IntersectionList.Create(xs.ToArray())));
}
public override IntersectionList LocalIntersect(Ray ray)
{
CheckAxis(ray.Origin.X, ray.Direction.X, out var xtmin, out var xtmax);
CheckAxis(ray.Origin.Y, ray.Direction.Y, out var ytmin, out var ytmax);
CheckAxis(ray.Origin.Z, ray.Direction.Z, out var ztmin, out var ztmax);
var tmin = Max(xtmin, ytmin, ztmin);
var tmax = Min(xtmax, ytmax, ztmax);
if (tmin > tmax)
{
return(IntersectionList.Empty());
}
return(IntersectionList.Create(
new Intersection(tmin, this),
new Intersection(tmax, this)));
}
private void CalculateRefraction(IntersectionList xs, out double n1, out double n2)
{
n1 = 0;
n2 = 0;
var containers = new List <Shape>();
foreach (var i in xs)
{
if (i.Equals(this))
{
if (containers.Count == 0)
{
n1 = 1.0;
}
else
{
n1 = containers.Last().Material.RefractiveIndex;
}
}
if (containers.Contains(i.Object))
{
containers.Remove(i.Object);
}
else
{
containers.Add(i.Object);
}
if (i.Equals(this))
{
if (containers.Count == 0)
{
n2 = 1.0;
}
else
{
n2 = containers.Last().Material.RefractiveIndex;
}
break;
}
}
}
public Interaction Precompute(Ray r, IntersectionList xs)
{
var t = this.T;
var obj = this.Object;
var point = r.GetPosition(t);
var eyev = -r.Direction;
var normalv = obj.GetNormal(point);
var inside = false;
if (normalv.Dot(eyev) < 0)
{
inside = true;
normalv = -normalv;
}
var overPoint = point + normalv * Epsilon;
var underPoint = point - normalv * Epsilon;
var reflectv = r.Direction.Reflect(normalv);
this.CalculateRefraction(xs, out var n1, out var n2);
return(new Interaction
{
T = t,
Object = obj,
Point = point,
OverPoint = overPoint,
UnderPoint = underPoint,
Eyev = eyev,
Normalv = normalv,
Reflectv = reflectv,
Inside = inside,
N1 = n1,
N2 = n2,
});
}
public Interaction Precompute(Ray r) => Precompute(r, IntersectionList.Create(this));
public override IntersectionList LocalIntersect(Ray ray)
{
List <Intersection> xs;
var o = ray.Origin;
var d = ray.Direction;
var a = (d.X * d.X) - (d.Y * d.Y) + (d.Z * d.Z);
var b = (2 * o.X * d.X) - (2 * o.Y * d.Y) + (2 * o.Z * d.Z);
var c = (o.X * o.X) - (o.Y * o.Y) + (o.Z * o.Z);
if (a == 0)
{
if (b == 0)
{
return(IntersectionList.Empty());
}
var t = -c / (2 * b);
xs = new List <Intersection>()
{
new Intersection(t, this),
};
this.IntersectCaps(ray, xs);
return(IntersectionList.Create(xs.ToArray()));
}
var disc = b * b - 4 * a * c;
if (disc < 0)
{
return(IntersectionList.Empty());
}
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;
}
xs = new List <Intersection>();
var y0 = o.Y + t0 * d.Y;
if (this.Minimum < y0 && y0 < this.Maximum)
{
xs.Add(new Intersection(t0, this));
}
var y1 = o.Y + t1 * d.Y;
if (this.Minimum < y1 && y1 < this.Maximum)
{
xs.Add(new Intersection(t1, this));
}
this.IntersectCaps(ray, xs);
return(IntersectionList.Create(xs.ToArray()));
}
