// http://gamedev.stackexchange.com/questions/18436/most-efficient-aabb-vs-ray-collision-algorithms
// release 0.050010 us
// debug 0.069480 us
public static RayDHitInfo CastRay(this RayD ray, Bounds bounds)
{
// lb is the corner of AABB with minimal coordinates - left bottom, rt is maximal corner
// r.org is origin of ray
double tt1 = (bounds.Min.X - ray.origin.X) / ray.direction.X;
double t2 = (bounds.Max.X - ray.origin.X) / ray.direction.X;
double t3 = (bounds.Min.Y - ray.origin.Y) / ray.direction.Y;
double t4 = (bounds.Max.Y - ray.origin.Y) / ray.direction.Y;
double t5 = (bounds.Min.Z - ray.origin.Z) / ray.direction.Z;
double t6 = (bounds.Max.Z - ray.origin.Z) / ray.direction.Z;
double tmin = Math.Max(Math.Max(Math.Min(tt1, t2), Math.Min(t3, t4)), Math.Min(t5, t6));
double tmax = Math.Min(Math.Min(Math.Max(tt1, t2), Math.Max(t3, t4)), Math.Max(t5, t6));
// if tmax < 0, ray (line) is intersecting AABB, but whole AABB is behing us
if (tmax < 0)
{
//t0 = tmax;
return(RayDHitInfo.NoHit);
}
//if (tmin > t1) return false;
// if tmin > tmax, ray doesn't intersect AABB
if (tmin > tmax)
{
//t0 = tmax;
return(RayDHitInfo.NoHit);
}
return(RayDHitInfo.HitAtRayDistance(tmin));
//t1 = tmin;
}
public static RayDHitInfo CastRay(this RayD ray, SphereD sphere)
{
var u = ray.direction;
var A = ray.origin;
var S = sphere.center;
var r = sphere.radius;
double _a = 1;
// if u is not normalized then:
//_a = u.x * u.x + u.y * u.y + u.z * u.z;
double _b =
(
(A.X * u.X) - (u.X * S.X) +
(A.Y * u.Y) - (u.Y * S.Y) +
(A.Z * u.Z) - (u.Z * S.Z)
) * 2;
double _c =
((A.X - S.X) * (A.X - S.X)) +
((A.Y - S.Y) * (A.Y - S.Y)) +
((A.Z - S.Z) * (A.Z - S.Z)) +
-(r * r);
// a*t*t + b*t + c
double determinant = _b * _b - 4 * _a * _c;
if (determinant < 0)
{
return(RayDHitInfo.NoHit); // no hit
}
double _2a = 2 * _a;
if (determinant > 0) // two hits
{
double dSqrt = (double)Math.Sqrt(determinant);
double t1 = (-_b + dSqrt) / _2a;
double t2 = (-_b - dSqrt) / _2a;
if (t1 < t2)
{
return(RayDHitInfo.HitAtRayDistance(t1));
}
else
{
return(RayDHitInfo.HitAtRayDistance(t2));
}
}
if (determinant == 0) // one hit
{
double t1 = -_b / _2a;
return(RayDHitInfo.HitAtRayDistance(t1));
}
return(RayDHitInfo.NoHit);
}
// Thomas Moller ray triangle intersection
// or http://www.lighthouse3d.com/tutorials/maths/ray-triangle-intersection/
// release 0.054317 us
// debug 0.602176 us
public static RayDHitInfo CastRay(this RayD ray, TriangleD triangle)
{
// TODO
/*
* Zde doplòte kód pro testování existence prùseèíku parsku s trojúhelníkem.
* Vypoètený parametr t spoleènì s trojúhelníkem triangle vložte ma konci této metody
* do metody ray.closest_hit, napø. takto
*
* return ray.closest_hit( t, triangle );
*
* Tato metoda vrátí true v pøípadì, že zadaný parametr t je menší než pøedchozí a zapíše
* do paprsku i ukazatel na zasažený trojúhelník, pøes který (metoda target) je možno následnì zjistit
* normálu (target.normal()) nebo materiál v bodì zásahu.
*/
const double ____EPSILON = 0.000001f;
Vector3d V1 = triangle.a;
Vector3d V2 = triangle.b;
Vector3d V3 = triangle.c;
Vector3d O = ray.origin; //RayD origin
Vector3d D = ray.direction; //RayD direction
Vector3d e1, e2; //Edge1, Edge2
Vector3d P, Q, T;
double det, inv_det, u, v;
double t;
//Find vectors for two edges sharing V1
e1 = V2 - V1;
e2 = V3 - V1;
//Begin calculating determinant - also used to calculate u parameter
P = D.Cross(e2);
//if determinant is near zero, ray lies in plane of triangle
det = e1.Dot(P);
//NOT CULLING
if (det > -____EPSILON && det < ____EPSILON)
{
return(RayDHitInfo.NoHit);
}
inv_det = 1.0f / det;
//calculate distance from V1 to ray origin
T = O - V1;
//Calculate u parameter and test bound
u = T.Dot(P) * inv_det;
//The intersection lies outside of the triangle
if (u < 0.0f || u > 1.0f)
{
return(RayDHitInfo.NoHit);
}
//Prepare to test v parameter
Q = T.Cross(e1);
//Calculate V parameter and test bound
v = D.Dot(Q) * inv_det;
//The intersection lies outside of the triangle
if (v < 0.0f || u + v > 1.0f)
{
return(RayDHitInfo.NoHit);
}
t = e2.Dot(Q) * inv_det;
if (t > ____EPSILON)
{ //ray intersection
return(RayDHitInfo.HitAtRayDistance(t));
}
return(RayDHitInfo.NoHit); // trojúhelník nenalezen
}
