private static BSPNodeInfo ReadBSPNode(BinaryReader reader)
{
BSPNodeInfo node = new BSPNodeInfo();
bool isLeaf = reader.ReadByte() != 0;
if (isLeaf)
{
UInt32 numTriangles = reader.ReadUInt32();
node.Triangles = new int[numTriangles];
for (UInt32 i = 0; i < numTriangles; i++)
{
node.Triangles[i] = reader.ReadInt32();
}
}
else
{
node.P.N = ReadVector3(reader);
node.P.D = reader.ReadSingle();
node.Back = ReadBSPNode(reader);
node.Front = ReadBSPNode(reader);
}
return(node);
}
private static int NodeTriangleTest(Vector3 p0, Vector3 p1, CollisionInfo collision, BSPNodeInfo node, ref Vector3 hitPoint)
{
if (node.Triangles.Length == 0)
{
return(-1);
}
Vector3 d = (p1 - p0);
float distanceToTarget = d.Length;
// If the end point is basically the same as the start point, then there is no occlusion
if (d.Length < Epsilon)
{
return(-1);
}
d = d.Normalize();
for (int i = 0; i < node.Triangles.Length; i++)
{
int t = node.Triangles[i];
var triangle = collision.Triangles[t];
var fixture = collision.Fixtures[triangle.fixture];
if (fixture.Hidden)
{
return(-1);
}
Vector3 v0 = collision.Vertices[triangle.i0];
Vector3 v1 = collision.Vertices[triangle.i1];
Vector3 v2 = collision.Vertices[triangle.i2];
float distance;
if (RayTestTriangle(out distance, p0, d, v0, v1, v2, ref hitPoint))
{
if (distance < distanceToTarget)
{
return(i);
}
}
}
return(-1);
}
private static bool SegmentTest(Vector3 p0, Vector3 p1, CollisionInfo collision, BSPNodeInfo node, int depth, ref SegmentTestInfo info)
{
if (node == null)
{
return(false);
}
info.NumNodesTested++;
info.MaxDepthReached = Math.Max(info.MaxDepthReached, depth);
if (node.IsLeaf)
{
TriangleInfo hitTriangle = new TriangleInfo();
int tri = NodeTriangleTest(p0, p1, collision, node, ref info.HitPoint);
info.NumTrianglesTested += (tri != -1) ? (tri + 1) : node.Triangles.Length;
info.HitTriangle = hitTriangle;
return(tri != -1);
}
else
{
float d0 = Vector3.Dot(node.P.N, p0) - node.P.D;
float d1 = Vector3.Dot(node.P.N, p1) - node.P.D;
if (d0 < -Epsilon && d1 < -Epsilon)
{
// Both points behind plane
return(SegmentTest(p0, p1, collision, node.Back, depth + 1, ref info));
}
else if (d0 > Epsilon && d1 > Epsilon)
{
// Both points in front of plane
return(SegmentTest(p0, p1, collision, node.Front, depth + 1, ref info));
}
else
{
// Points span plane
return(SegmentTest(p0, p1, collision, node.Front, depth + 1, ref info) || SegmentTest(p0, p1, collision, node.Back, depth + 1, ref info));
}
}
}