/// <summary>
/// Finds the smallest potential bounding sphere for two objects in this list. Removes both objects from the list, adds them to a
/// new bounding sphere/BVH node and then adds that to the list. Also returns the BVH node.
/// </summary>
/// <param name="spheres">A list of spheres</param>
/// <returns>The BVH node with the smallest volume</returns>
private BVHNode SmallestBoundingSphere(List <Sphere> spheres)
{
float minBsRadius = float.MaxValue;
int sphere1 = -1, sphere2 = -1;
for (int i = 0; i < spheres.Count - 1; i++)
{
for (int j = i + 1; j < spheres.Count; j++)
{
float bsRadius = ((spheres[j].Position - spheres[i].Position).Length() + spheres[i].R + spheres[j].R) / 2;
if (bsRadius < minBsRadius)
{
minBsRadius = bsRadius;
sphere1 = i;
sphere2 = j;
}
}
}
BVHNode node = new BVHNode(spheres[sphere1], spheres[sphere2]);
spheres.Remove(spheres[sphere2]);
spheres.Remove(spheres[sphere1]);
spheres.Add(node);
return(node);
}
/// <summary>
/// Builds the bounding volume hierarchy based on <see cref="spheres"/>.
/// </summary>
private void CreateBVH()
{
List <Sphere> spheresTemp = new List <Sphere>(spheres);
while (spheresTemp.Count > 1)
{
Root = SmallestBoundingSphere(spheresTemp);
}
}
