/// <summary>
/// determines if the line segment defined by v1 and v2 intersects any geometry in the tree.
/// </summary>
/// <param name="v1">vertex that defines the start of the ray</param>
/// <param name="v2">vertex that defines the end of the ray</param>
/// <returns>true if the ray collides with the mesh</returns>
bool SplitsRay(Vector3 v1, Vector3 v2)
{
var v1IsInFront = IsInFront(v1);
var v2IsInFront = IsInFront(v2);
var result = v1IsInFront != v2IsInFront;
if (!result)
{
/// both vertices are on the same side of the plane,
/// so this node doesn't split anything. Check it's children.
if (v1IsInFront && front != null)
{
result = front.SplitsRay(v1, v2);
}
else if (!v1IsInFront && back != null)
{
result = back.SplitsRay(v1, v2);
}
}
else
{
/// this plane splits the ray, but the intersection point may not be within the face boundaries.
/// 1. calculate the intersection of the plane and the ray : intersection
/// 2. create two new line segments: v1->intersection and intersection->v2
/// 3. Recursively check those two segments against the rest of the tree.
var intersection = new Vector3();
/// insert code to magically calculate the intersection here.
var frontSegmentSplits = false;
var backSegmentSplits = false;
if (front != null)
{
if (v1IsInFront)
{
frontSegmentSplits = front.SplitsRay(v1, intersection);
}
else if (v2IsInFront)
{
frontSegmentSplits = front.SplitsRay(v2, intersection);
}
}
if (back != null)
{
if (!v1IsInFront)
{
backSegmentSplits = back.SplitsRay(v1, intersection);
}
else if (!v2IsInFront)
{
backSegmentSplits = back.SplitsRay(v2, intersection);
}
}
result = frontSegmentSplits || backSegmentSplits;
}
return(result);
}
