/// <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
var 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;
var 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
var i = 0;
var 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
var seg = new Segment(sphere.Center, sphere.Center + movementVector);
//Box extent and center
var extent = Aabb.calculateAxisRadius();
var center = Aabb.PMin + extent;
//Edge
if (i == 2)
{
//Generar los dos puntos extremos del Edge
float[] extentDir = { sign[0], sign[1], sign[2] };
var zeroIndex = sign[0] == 0 ? 0 : (sign[1] == 0 ? 1 : 2);
extentDir[zeroIndex] = 1;
var capsuleA = center + new Vector3(extent.X * extentDir[0], extent.Y * extentDir[1], extent.Z * extentDir[2]);
extentDir[zeroIndex] = -1;
var 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)
{
var tmin = float.MaxValue;
var 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);
}
