/// <summary>
/// Colisiona un BoundingSphere en movimiento contra el BoundingBox.
/// Si hay colision devuelve el instante t de colision mas proximo y el punto q de colision mas cercano
/// </summary>
/// <param name="sphere">BoundingSphere</param>
/// <param name="movementVector">movimiento del BoundingSphere</param>
/// <param name="t">Menor instante de colision</param>
/// <param name="q">Punto mas cercano de colision</param>
/// <param name="n">Normal de la cara colisionada</param>
/// <returns>True si hay colision</returns>
public override bool intersectMovingSphere(TgcBoundingSphere sphere, Vector3 movementVector, TgcBoundingSphere movementSphere, out float t, out Vector3 q, out Vector3 n)
{
t = -1f;
q = Vector3.Empty;
n = Vector3.Empty;
// Compute the AABB resulting from expanding b by sphere radius r
TgcBoundingBox.AABBStruct e = aabb.toStruct();
e.min.X -= sphere.Radius; e.min.Y -= sphere.Radius; e.min.Z -= sphere.Radius;
e.max.X += sphere.Radius; e.max.Y += sphere.Radius; e.max.Z += sphere.Radius;
// Intersect ray against expanded AABB e. Exit with no intersection if ray
// misses e, else get intersection point p and time t as result
Vector3 p;
TgcRay.RayStruct ray = new TgcRay.RayStruct();
ray.origin = sphere.Center;
ray.direction = movementVector;
if (!intersectRayAABB(ray, e, out t, out p) || t > 1.0f)
{
return(false);
}
// Compute which min and max faces of b the intersection point p lies
// outside of. Note, u and v cannot have the same bits set and
// they must have at least one bit set among them
int i = 0;
int[] sign = new int[3];
if (p.X < aabb.PMin.X)
{
sign[0] = -1;
i++;
}
if (p.X > aabb.PMax.X)
{
sign[0] = 1;
i++;
}
if (p.Y < aabb.PMin.Y)
{
sign[1] = -1;
i++;
}
if (p.Y > aabb.PMax.Y)
{
sign[1] = 1;
i++;
}
if (p.Z < aabb.PMin.Z)
{
sign[2] = -1;
i++;
}
if (p.Z > aabb.PMax.Z)
{
sign[2] = 1;
i++;
}
//Face
if (i == 1)
{
n = new Vector3(sign[0], sign[1], sign[2]);
q = sphere.Center + t * movementVector - sphere.Radius * n;
return(true);
}
// Define line segment [c, c+d] specified by the sphere movement
Segment seg = new Segment(sphere.Center, sphere.Center + movementVector);
//Box extent and center
Vector3 extent = aabb.calculateAxisRadius();
Vector3 center = aabb.PMin + extent;
//Edge
if (i == 2)
{
//Generar los dos puntos extremos del Edge
float[] extentDir = new float[] { sign[0], sign[1], sign[2] };
int zeroIndex = sign[0] == 0 ? 0 : (sign[1] == 0 ? 1 : 2);
extentDir[zeroIndex] = 1;
Vector3 capsuleA = center + new Vector3(extent.X * extentDir[0], extent.Y * extentDir[1], extent.Z * extentDir[2]);
extentDir[zeroIndex] = -1;
Vector3 capsuleB = center + new Vector3(extent.X * extentDir[0], extent.Y * extentDir[1], extent.Z * extentDir[2]);
//Colision contra el Edge hecho Capsula
if (intersectSegmentCapsule(seg, new Capsule(capsuleA, capsuleB, sphere.Radius), out t))
{
n = new Vector3(sign[0], sign[1], sign[2]);
n.Normalize();
q = sphere.Center + t * movementVector - sphere.Radius * n;
return(true);
}
}
//Vertex
if (i == 3)
{
float tmin = float.MaxValue;
Vector3 capsuleA = center + new Vector3(extent.X * sign[0], extent.Y * sign[1], extent.Z * sign[2]);
Vector3 capsuleB;
capsuleB = center + new Vector3(extent.X * -sign[0], extent.Y * sign[1], extent.Z * sign[2]);
if (intersectSegmentCapsule(seg, new Capsule(capsuleA, capsuleB, sphere.Radius), out t))
{
tmin = TgcCollisionUtils.min(t, tmin);
}
capsuleB = center + new Vector3(extent.X * sign[0], extent.Y * -sign[1], extent.Z * sign[2]);
if (intersectSegmentCapsule(seg, new Capsule(capsuleA, capsuleB, sphere.Radius), out t))
{
tmin = TgcCollisionUtils.min(t, tmin);
}
capsuleB = center + new Vector3(extent.X * sign[0], extent.Y * sign[1], extent.Z * -sign[2]);
if (intersectSegmentCapsule(seg, new Capsule(capsuleA, capsuleB, sphere.Radius), out t))
{
tmin = TgcCollisionUtils.min(t, tmin);
}
if (tmin == float.MaxValue)
{
return(false); // No intersection
}
t = tmin;
n = new Vector3(sign[0], sign[1], sign[2]);
n.Normalize();
q = sphere.Center + t * movementVector - sphere.Radius * n;
return(true); // Intersection at time t == tmin
}
return(false);
}
/// <summary>
/// Retorna true si hubo interseccion con el terreno y setea el collisionPoint.
/// </summary>
/// <param name="ray"></param>
/// <param name="collisionPoint"></param>
/// <returns></returns>
public bool intersectRay(TgcRay ray, out Vector3 collisionPoint)
{
collisionPoint = Vector3.Empty;
Matrix scaleInv = Matrix.Scaling(new Vector3(1 / ScaleXZ, 1 / ScaleY, 1 / ScaleXZ));
Vector3 a = Vector3.TransformCoordinate(ray.Origin, scaleInv) - traslation;
Vector3 r = Vector3.TransformCoordinate(ray.Direction, scaleInv);
if (a.Y < minIntensity)
{
return(false);
}
Vector3 q;
//Me fijo si intersecta con el BB del terreno.
if (!TgcCollisionUtils.intersectRayAABB(new TgcRay(a, r).toStruct(), aabb.toStruct(), out q))
{
return(false);
}
float minT = 0;
//Obtengo el T de la interseccion.
if (q != a)
{
if (r.X != 0)
{
minT = (q.X - a.X) / r.X;
}
else if (r.Y != 0)
{
minT = (q.Y - a.Y) / r.Y;
}
else if (r.Z != 0)
{
minT = (q.Z - a.Z) / r.Z;
}
}
//Me desplazo por el rayo hasta que su altura sea menor a la del terreno en ese punto
//o me salga del AABB.
float t = 0;
float step = 1;
for (t = minT; ; t += step)
{
collisionPoint = a + t * r;
float y;
if (!interpoledIntensity(collisionPoint.X, collisionPoint.Z, out y))
{
return(false);
}
if (collisionPoint.Y <= y + float.Epsilon)
{
collisionPoint.Y = y;
collisionPoint = Vector3.TransformCoordinate(collisionPoint + traslation, Matrix.Scaling(ScaleXZ, ScaleY, ScaleXZ));
return(true);
}
}
}
