public static CollisionDetails GetFirstCollision(Octree tree, Shapes.Ray r)
{
var c = new CollisionDetails {
Distance = double.PositiveInfinity
};
double distanceTravelled = 0; //distance traveled since the ray's origin
//Algorithm starts at the ray's origin and in the root node.
Node n = tree.GetRoot();
c.CheckCollisionSet(n.Content, r);
var pos = r.Origin;
if (!n.Encloses(pos))
{
throw new Exception("Ray's origin is not located in the octree!");
}
do
{
//March to the leaf containing "pos" and check collisions
n = n.MarchToCheckingCollisions(pos, c, r);
//No leaf is containing "pos" -> left tree -> stop searching
if (n == null)
{
break;
}
//march out of current node
double d = RayCube.GetDistanceToBorderPlane(pos, r.Direction, n.Center, n.Width / 2) + Constants.EPS * 1e4;
//distance traveled since the ray's origin
pos = pos + r.Direction * d;
distanceTravelled += d;
//in case eps was not enough
while (n.Encloses(pos))
{
d = Constants.EPS * 1e4;
pos = pos + r.Direction * d;
distanceTravelled += d;
}
/**
* When passing a box-border, all intersection tests between the ray's origin and the
* box-border-intersection-point must have taken place (and some beyond the box-border too).
* Therefore, if an intersection located between the ray's origin and the box-border has been found, this
* must be the nearest intersection and the search may stop.
*/
} while (c.Distance > distanceTravelled);
return(c);
}
public static Octree BuildTree(Vect3 center, IList <I3DObject> objects)
{
double maxQuadDist = 0;
Log.Debug("Building octree... ");
foreach (I3DObject o in objects)
{
Sphere s = o.GetBoundingSphere();
if (s != null)
{
Vect3 dist = center - s.Position;
double qdist = s.Radius;
if (double.IsInfinity(qdist) || Double.IsNaN(qdist))
{
throw new Exception("Invalid BoundingSphere: " + s + " from " + o);
}
qdist = qdist * qdist + dist.QuadLength();
if (maxQuadDist < qdist)
{
maxQuadDist = qdist;
}
}
}
/**
* Workaround: *2.1 instead of *2, because rays must always start inside an octree for RayPath.
* To fix this problem, a RayPath should allow ray-origins outside the octree, but this would need
* an additional ray-cube intersection test which is currently not implemented. Another downside of
* this is that the camera must always be located inside the octree - it must not be moved outside.
*/
double sizeHint = System.Math.Sqrt(maxQuadDist) * 2.1;
Sw.Restart();
Octree t;
while (true)
{
t = new Octree(center, sizeHint);
foreach (I3DObject o in objects)
{
if (!t.Root.Insert(o, o.GetBoundingSphere()))
{
sizeHint *= 2;
Log.Warn("Warning - resize needed!");
goto cont;
}
}
break;
cont:
{
}
}
t.GetRoot().Compress();
Sw.Stop();
Log.Debug(string.Format("{0} ms\n", Sw.ElapsedMilliseconds));
Log.Debug(string.Format(" - contains {0} of {1} elements ({2:0.##}%)",
t.GetRoot().GetSize(), objects.Count,
t.GetRoot().GetSize() / (float)objects.Count * 100));
Log.Debug(" - avg depth: " + t.GetAverageObjectDepth());
Log.Debug(" - node count: " + t.GetRoot().GetNodeCount());
Log.Debug(" - objects per node: " + t.GetRoot().GetSize() / (float)t.GetRoot().GetNodeCount());
return(t);
}
