/// <summary>
/// Plane/Box intersection test.
/// </summary>
/// <param name="plane"></param>
/// <param name="box"></param>
/// <returns>True if there was an intersection, false otherwise.</returns>
public static bool Intersects(Plane plane, AxisAlignedBox box)
{
if (box.IsNull)
{
return(false);
}
// Get corners of the box
Vector3[] corners = box.Corners;
// Test which side of the plane the corners are
// Intersection occurs when at least one corner is on the
// opposite side to another
PlaneSide lastSide = plane.GetSide(corners[0]);
for (int corner = 1; corner < 8; corner++)
{
if (plane.GetSide(corners[corner]) != lastSide)
{
return(true);
}
}
return(false);
}
/// <summary>
/// Intersection test with an <see cref="AxisAlignedBox"/>.
/// </summary>
/// <remarks>
/// May return false positives but will never miss an intersection.
/// </remarks>
/// <param name="box">Box to test.</param>
/// <returns>True if interesecting, false otherwise.</returns>
public bool Intersects(AxisAlignedBox box)
{
if (box.IsNull)
{
return(false);
}
// If all points are on outside of any plane, we fail
Vector3[] points = box.Corners;
for (int i = 0; i < planes.Count; i++)
{
Plane plane = planes[i];
// Test which side of the plane the corners are
// Intersection fails when at all corners are on the
// outside of one plane
bool splittingPlane = true;
for (int corner = 0; corner < 8; corner++)
{
if (plane.GetSide(points[corner]) != outside)
{
// this point is on the wrong side
splittingPlane = false;
break;
}
}
if (splittingPlane)
{
// Found a splitting plane therefore return not intersecting
return(false);
}
}
// couldn't find a splitting plane, assume intersecting
return(true);
}
/// <summary>
/// Ray/PlaneBoundedVolume intersection test.
/// </summary>
/// <param name="ray"></param>
/// <param name="volume"></param>
/// <returns>Struct that contains a bool (hit?) and distance.</returns>
public static IntersectResult Intersects(Ray ray, PlaneBoundedVolume volume)
{
List <Plane> planes = volume.planes;
float maxExtDist = 0.0f;
float minIntDist = float.PositiveInfinity;
float dist, denom, nom;
for (int i = 0; i < planes.Count; i++)
{
Plane plane = planes[i];
denom = plane.Normal.Dot(ray.Direction);
if (MathUtil.Abs(denom) < float.Epsilon)
{
// Parallel
if (plane.GetSide(ray.Origin) == volume.outside)
{
return(new IntersectResult(false, 0));
}
continue;
}
nom = plane.Normal.Dot(ray.Origin) + plane.D;
dist = -(nom / denom);
if (volume.outside == PlaneSide.Negative)
{
nom = -nom;
}
if (dist > 0.0f)
{
if (nom > 0.0f)
{
if (maxExtDist < dist)
{
maxExtDist = dist;
}
}
else
{
if (minIntDist > dist)
{
minIntDist = dist;
}
}
}
else
{
//Ray points away from plane
if (volume.outside == PlaneSide.Negative)
{
denom = -denom;
}
if (denom > 0.0f)
{
return(new IntersectResult(false, 0));
}
}
}
if (maxExtDist > minIntDist)
{
return(new IntersectResult(false, 0));
}
return(new IntersectResult(true, maxExtDist));
}
