/// <summary>
/// Generar OBB a partir de AABB
/// </summary>
/// <param name="aabb">BoundingBox</param>
/// <returns>OBB generado</returns>
public static OBBStruct computeFromAABB(TgcBoundingAxisAlignBox.AABBStruct aabb)
{
var obb = new OBBStruct();
obb.extents = (aabb.max - aabb.min) * 0.5f;
obb.center = aabb.min + obb.extents;
obb.orientation = new[] { new Vector3(1, 0, 0), new Vector3(0, 1, 0), new Vector3(0, 0, 1) };
return(obb);
}
/// <summary>
/// Interseccion entre un Ray y un AABB
/// </summary>
/// <param name="ray">Ray</param>
/// <param name="aabb">AABB</param>
/// <param name="tmin">Instante minimo de colision</param>
/// <param name="q">Punto minimo de colision</param>
/// <returns>True si hay colision</returns>
private bool intersectRayAABB(TgcRay.RayStruct ray, TgcBoundingAxisAlignBox.AABBStruct aabb, out float tmin,
out TGCVector3 q)
{
var aabbMin = TgcCollisionUtils.toArray(aabb.min);
var aabbMax = TgcCollisionUtils.toArray(aabb.max);
var p = TgcCollisionUtils.toArray(ray.origin);
var d = TgcCollisionUtils.toArray(ray.direction);
tmin = 0.0f; // set to -FLT_MAX to get first hit on line
var tmax = float.MaxValue; // set to max distance ray can travel (for segment)
q = TGCVector3.Empty;
// For all three slabs
for (var i = 0; i < 3; i++)
{
if (FastMath.Abs(d[i]) < float.Epsilon)
{
// Ray is parallel to slab. No hit if origin not within slab
if (p[i] < aabbMin[i] || p[i] > aabbMax[i])
{
return(false);
}
}
else
{
// Compute intersection t value of ray with near and far plane of slab
var ood = 1.0f / d[i];
var t1 = (aabbMin[i] - p[i]) * ood;
var t2 = (aabbMax[i] - p[i]) * ood;
// Make t1 be intersection with near plane, t2 with far plane
if (t1 > t2)
{
TgcCollisionUtils.swap(ref t1, ref t2);
}
// Compute the intersection of slab intersection intervals
tmin = TgcCollisionUtils.max(tmin, t1);
tmax = TgcCollisionUtils.min(tmax, t2);
// Exit with no collision as soon as slab intersection becomes empty
if (tmin > tmax)
{
return(false);
}
}
}
// Ray intersects all 3 slabs. Return point (q) and intersection t value (tmin)
q = ray.origin + ray.direction * tmin;
return(true);
}
