/// <summary>
/// Creates a new orthopgrhic camera for a 3-dimensional scene, looking at a particular point.
/// </summary>
/// <param name="position">Position of the camera in 3-dimensional space.</param>
/// <param name="lookAt">The point the camera should look at.</param>
/// <param name="width">The width of the projection plane.</param>
/// <param name="height">The height of the projection plane.</param>
public OrthographicCamera(Point position, Point lookAt, float width, float height)
: base(position, width, height)
{
var normal = (lookAt - position).Normalise();
var yAxis = new Vector(0.0f, 1.0f, 0.0f);
Right = (yAxis % normal).Normalise();
Up = (normal % Right).Normalise();
}
/// <summary>
/// Creates a new orthographic camera for a 3-dimensional scene.
/// </summary>
/// <param name="position">Position of the camera in the 3-dimensional scene.</param>
/// <param name="up">The up direction of the viewing plane.</param>
/// <param name="right">The right direction of the viewing plane.</param>
/// <param name="width">The width of the projection plane.</param>
/// <param name="height">The height of the projection plane.</param>
public OrthographicCamera(Point position, Vector up, Vector right, float width, float height)
: base(position, width, height)
{
Up = up.Normalise();
Right = right.Normalise();
if (Right * Up != 0.0f) {
var normal = (Right % Up).Normalise();
Right = (Up % normal).Normalise();
Up = (normal % Right).Normalise();
}
}
/// <summary>
/// Constructs a ray in 3-dimensional space.
/// </summary>
/// <param name="start">The starting point of the ray.</param>
/// <param name="direction">The direction of the ray.</param>
public Ray(Point start, Vector direction)
{
if (start == null) {
throw new ArgumentNullException("start");
}
if (direction == null) {
throw new ArgumentNullException("direction");
}
if (direction.Norm() == 0.0f) {
throw new ArgumentOutOfRangeException("direction");
}
Start = start;
Direction = direction;
}
/// <summary>
/// Creates a triangle in 3-dimensional space.
/// </summary>
/// <remarks>We assume points are specified in clockwise fashion to form the top of the triangle.</remarks>
/// <param name="p1">The first point of the triangle.</param>
/// <param name="p2">The second point of the triangle.</param>
/// <param name="p3">The third point of the triangle.</param>
public Triangle(Point p1, Point p2, Point p3)
{
if (p1 == null) {
throw new ArgumentNullException("p1");
}
if (p2 == null) {
throw new ArgumentNullException("p2");
}
if (p3 == null) {
throw new ArgumentNullException("p3");
}
P1 = p1;
P2 = p2;
P3 = p3;
// Pre-calculate.
normal = ((P2 - P1) % (P3 - P1)).Normalise();
if (normal == new Vector(0.0f, 0.0f, 0.0f)) {
// Points form a line.
throw new ArgumentOutOfRangeException("p3");
}
d = normal * new Vector(P1.X, p1.Y, p1.Z);
}
/// <summary>
/// Calculates the distance along the specified ray the first intersection with this object occurs.
/// </summary>
/// <param name="ray">The ray to test.</param>
/// <returns>The distance along the ray the first intersection with this object occurs. If no intersection, returns a negative value.</returns>
public override float IntersectDistance(Ray ray)
{
if (ray == null) {
throw new ArgumentNullException("ray");
}
var nd = normal * ray.Direction;
if (nd == 0) {
return -1.0f;
}
var start = new Vector(ray.Start.X, ray.Start.Y, ray.Start.Z);
var t = (d - normal * start) / (nd);
var q = ray.Start + t * ray.Direction;
if (((P2 - P1) % (q - P1)) * normal < 0.0f) {
return -1.0f;
}
if (((P3 - P2) % (q - P2)) * normal < 0.0f) {
return -1.0f;
}
if (((P1 - P3) % (q - P3)) * normal < 0.0f) {
return -1.0f;
}
return t;
}