public void If_the_ray_does_not_point_at_the_AABB_the_result_is_false_and_the_distance_is_set_to_infinity()
{
var box = new AxisAlignedBoundingBox(new Point(1, 1, 1), new Point(2, 2, 2));
var ray = new Ray(new Point(0.5, -1, 2), -Vector.UnitY);
Assert.False(box.IntersectsRay(ray, 0, double.PositiveInfinity));
}
public void If_the_ray_points_at_the_AABB_the_result_is_true_and_the_distance_is_set_correctly()
{
var box = new AxisAlignedBoundingBox(new Point(0, 0, 0), new Point(2, 2, 2));
var ray = new Ray(new Point(-1, 1, 1), new Vector(1, 0.1, 0.2).ToUnitVector());
Assert.True(box.IntersectsRay(ray, 0, double.PositiveInfinity));
}
public void RenderScene(RenderingContext context)
{
Ensure.That("context", context).IsNotNull();
//// transforms from image space into camera space
//var imageMatrix = Matrix.Scaling(1d / context.Target.Width, 1d / context.Target.Height, 1);
foreach (var pixel in context.Target.GetPixels()) {
var colorAccumulator = Color.Black;
foreach (var pixelSpaceSample in _pixelSampleGenerator.GenerateSamples(context.SamplesPerPixel)) {
var imageSpaceSample = new Point(pixel.X + pixelSpaceSample.X, pixel.Y + pixelSpaceSample.Y, 1);
var projectionSpaceRay = new Ray(context.ImageMatrix * imageSpaceSample, Vector.UnitZ);
var cameraSpaceRay = context.ProjectionMatrix * projectionSpaceRay;
// TODO: transform camera space ray into world space
colorAccumulator += _algorithm.DetermineRayColor(cameraSpaceRay, context.World);
}
context.Target.SetPixelColor(pixel, colorAccumulator / context.SamplesPerPixel);
}
}
public Intersection FindClosestIntersectionWith(Ray ray)
{
var intersection = Geometry.FindClosestIntersectionWith(ray);
if (intersection == null)
return null;
return intersection.WithMaterial(Material);
}
public void If_the_triangle_is_behind_the_ray_the_result_is_null()
{
var ray = new Ray(Point.Zero, -Vector.UnitX);
var triangle = new Triangle(
new Point(2, 2, 0),
new Point(2, -2, 2),
new Point(2, -2, -2)
);
Assert.Null(triangle.FindClosestIntersectionWith(ray));
}
public void If_the_ray_points_at_the_triangle_the_correct_distance_is_set_on_the_result()
{
var ray = new Ray(Point.Zero, Vector.UnitX);
var triangle = new Triangle(
new Point(2, 2, 0),
new Point(2, -2, 2),
new Point(2, -2, -2)
);
Assert.Equal(2d, triangle.FindClosestIntersectionWith(ray).Distance);
}
public static void The_returned_distance_is_the_distance_from_the_ray_origin_to_the_closest_edge_of_the_sphere()
{
var sphere = new Sphere(new Point(0, 0, 2), 1);
var ray = new Ray(Point.Zero, Vector.UnitZ);
Assert.Equal(1, sphere.FindClosestIntersectionWith(ray).Distance);
sphere = new Sphere(new Point(0, 0, -2), 1);
ray = new Ray(Point.Zero, -Vector.UnitZ);
Assert.Equal(1, sphere.FindClosestIntersectionWith(ray).Distance);
sphere = new Sphere(new Point(15, 0, 0), 3);
ray = new Ray(Point.Zero, Vector.UnitX);
Assert.Equal(12, sphere.FindClosestIntersectionWith(ray).Distance);
}
public Intersection FindClosestIntersectionWith(Ray ray)
{
Intersection closest = null;
foreach(var intersectable in _geometry) {
var intersection = intersectable.FindClosestIntersectionWith(ray);
if (closest == null || (intersection != null && intersection.Distance < closest.Distance)) {
closest = intersection;
}
}
return closest;
}
public Intersection FindClosestIntersectionWith(Ray ray)
{
Intersection closest = null;
if (_left != null && _leftBounds.IntersectsRay(ray, 0, double.PositiveInfinity)) {
closest = _left.FindClosestIntersectionWith(ray);
}
if (_right != null && _rightBounds.IntersectsRay(ray, 0, (closest != null) ? closest.Distance : double.PositiveInfinity)) {
closest = Intersection.Closest(closest, _right.FindClosestIntersectionWith(ray));
}
return closest;
}
/// <summary>
/// TODO: This method is BUTT SLOW. For now it just loops over all of the triangles in the mesh and returns the closest intersection...
/// </summary>
public Intersection FindClosestIntersectionWith(Ray ray)
{
if (_boundingBox == null) {
_boundingBox = GetBoundingBox();
}
if (!_boundingBox.IntersectsRay(ray, 0, double.PositiveInfinity)) {
return null;
}
return Triangles
.Select(triangle => triangle.FindClosestIntersectionWith(ray))
.WhereNotNull()
.OrderBy(intersection => intersection.Distance)
.FirstOrDefault();
}
public void For_ray_directions_with_zeros_the_result_is_still_true_for_valid_intersections()
{
var box = new AxisAlignedBoundingBox(new Point(0, 0, 0), new Point(2, 2, 2));
var ray = new Ray(new Point(-1, 1, 1), Vector.UnitX);
Assert.True(box.IntersectsRay(ray, 0, double.PositiveInfinity));
box = new AxisAlignedBoundingBox(new Point(0, 0, 0), new Point(2, 2, 2));
ray = new Ray(new Point(1, -1, 1), Vector.UnitY);
Assert.True(box.IntersectsRay(ray, 0, double.PositiveInfinity));
box = new AxisAlignedBoundingBox(new Point(0, 0, 0), new Point(2, 2, 2));
ray = new Ray(new Point(1, 1, -1), Vector.UnitZ);
Assert.True(box.IntersectsRay(ray, 0, double.PositiveInfinity));
}
public Intersection FindClosestIntersectionWith(Ray ray)
{
var between = ray.Origin - Position;
var b = Vector.DotProduct(between, ray.Direction);
var c = between.SquaredLength - (Radius * Radius);
var d = b * b - c;
if (d <= 0) {
return null;
}
var distance = (b > 0)
? -b + System.Math.Sqrt(d)
: -b - System.Math.Sqrt(d);
return new Intersection(ray, distance);
}
/// <summary>
/// Performs ray-triangle intersection based on Moller-Trubmore 97
/// </summary>
public Intersection FindClosestIntersectionWith(Ray ray)
{
var translated = ray.Origin - _a;
var edge1 = _b - _a;
var edge2 = _c - _a;
var p = Vector.CrossProduct(ray.Direction, edge2);
var q = Vector.CrossProduct(translated, edge1);
var determinant = Vector.DotProduct(p, edge1);
if (determinant == 0) {
return null;
}
var u = Vector.DotProduct(p, translated) / determinant;
// u + v must be between 0 and 1, which means that u must also be
if (u < 0d || u > 1d) {
return null;
}
var v = Vector.DotProduct(q, ray.Direction) / determinant;
if (v < 0d || u + v > 1d) {
return null;
}
// distance = t in the original algorithm
var distance = Vector.DotProduct(q, edge2) / determinant;
if (distance < 0d) {
return null;
}
return new Intersection(ray, distance);
}
public static void If_the_ray_points_at_the_sphere_the_result_is_not_null()
{
var sphere = new Sphere(new Point(0, 0, 5), 1);
var ray = new Ray(Point.Zero, Vector.UnitZ);
Assert.NotNull(sphere.FindClosestIntersectionWith(ray));
}
public bool IntersectsRay(Ray ray, double min, double max)
{
double tmin, tmax, tYMin, tYMax, tZMin, tZMax;
if (ray.Direction.X > 0) {
tmin = (Min.X - ray.Origin.X) / ray.Direction.X;
tmax = (Max.X - ray.Origin.X) / ray.Direction.X;
}
else if(ray.Direction.X < 0) {
tmax = (Min.X - ray.Origin.X) / ray.Direction.X;
tmin = (Max.X - ray.Origin.X) / ray.Direction.X;
}
else {
tmin = double.NegativeInfinity;
tmax = double.PositiveInfinity;
}
if (ray.Direction.Y > 0) {
tYMin = (Min.Y - ray.Origin.Y) / ray.Direction.Y;
tYMax = (Max.Y - ray.Origin.Y) / ray.Direction.Y;
}
else if (ray.Direction.Y < 0) {
tYMax = (Min.Y - ray.Origin.Y) / ray.Direction.Y;
tYMin = (Max.Y - ray.Origin.Y) / ray.Direction.Y;
}
else {
tYMin = double.NegativeInfinity;
tYMax = double.PositiveInfinity;
}
if(tmin > tYMax || tYMin > tmax)
return false;
if (tYMin > tmin)
tmin = tYMin;
if (tYMax < tmax)
tmax = tYMax;
if (ray.Direction.Z > 0) {
tZMin = (Min.Z - ray.Origin.Z) / ray.Direction.Z;
tZMax = (Max.Z - ray.Origin.Z) / ray.Direction.Z;
}
else if (ray.Direction.Z < 0) {
tZMax = (Min.Z - ray.Origin.Z) / ray.Direction.Z;
tZMin = (Max.Z - ray.Origin.Z) / ray.Direction.Z;
}
else {
tZMin = double.NegativeInfinity;
tZMax = double.PositiveInfinity;
}
if(tmin > tZMax || tZMin > tmax)
return false;
if (tZMin > tmin)
tmin = tZMin;
if (tZMax < tmax)
tmax = tZMax;
return (tmin < max) && (tmax > min);
}
public Color DetermineRayColor(Ray ray, IIntersectable scene)
{
var intersection = scene.FindClosestIntersectionWith(ray);
return intersection == null ? Color.Black : intersection.Color;
}