/// <summary>
/// Moves a portable object along a ray, taking into account portal teleportation. Portal velocity is ignored for this method.
/// </summary>
/// <param name="portalable">Instance travelling along ray.</param>
/// <param name="portals">Collection of portals used for portal teleportation.</param>
/// <param name="portalEnter">Callback that is executed after entering a portal.</param>
public static void RayCast(IPortalable portalable, IEnumerable<IPortal> portals, Settings settings, Action<EnterCallbackData, double> portalEnter = null)
{
Debug.Assert(settings.MaxIterations >= 0);
Debug.Assert(portalable != null);
Debug.Assert(portals != null);
Debug.Assert(settings.TimeScale >= 0);
Debug.Assert(!(portalable is IPortal));
if (portalable.GetVelocity().Position.Length == 0 || settings.TimeScale == 0)
{
return;
}
_rayCast(
portalable,
portals,
portalable.GetVelocity().Position.Length * settings.TimeScale,
null,
portalEnter,
settings,
0);
}
private static void _rayCast(IPortalable placeable, IEnumerable<IPortal> portals, double movementLeft, IPortal portalPrevious, Action<EnterCallbackData, double> portalEnter, Settings settings, int count)
{
Transform2 begin = placeable.GetTransform();
Transform2 velocity = placeable.GetVelocity().Multiply(settings.TimeScale);
if (settings.MaxIterations <= count)
{
//If we run out of iterations before running out of movement, call _rayEnd with 0 movementLeft just to make sure the AdjustEnpoint setting is handled.
_rayEnd(placeable, portals, 0, portalPrevious, settings, begin, velocity);
return;
}
if (!placeable.IsPortalable)
{
_rayEnd(placeable, portals, movementLeft, portalPrevious, settings, begin, velocity);
return;
}
double distanceMin = movementLeft;
IPortal portalNearest = null;
IntersectCoord intersectNearest = new IntersectCoord();
LineF ray = new LineF(begin.Position, begin.Position + velocity.Position);
foreach (IPortal p in portals)
{
if (!Portal.IsValid(p) || portalPrevious == p)
{
continue;
}
LineF portalLine = new LineF(Portal.GetWorldVerts(p));
IntersectCoord intersect = MathExt.LineLineIntersect(portalLine, ray, true);
double distance = ((Vector2d)begin.Position - intersect.Position).Length;
if (intersect.Exists && distance < distanceMin)
{
distanceMin = distance;
portalNearest = p;
intersectNearest = intersect;
}
}
if (portalNearest != null)
{
movementLeft -= distanceMin;
double t = (velocity.Position.Length - movementLeft) / velocity.Position.Length;
begin.Position = (Vector2)intersectNearest.Position;
placeable.SetTransform(begin);
Portal.Enter(portalNearest, placeable, (float)intersectNearest.TFirst, true);
portalEnter?.Invoke(new EnterCallbackData(portalNearest, placeable, intersectNearest.TFirst), t);
movementLeft *= Math.Abs(placeable.GetTransform().Size / begin.Size);
_rayCast(placeable, portals, movementLeft, portalNearest.Linked, portalEnter, settings, count + 1);
}
else
{
_rayEnd(placeable, portals, movementLeft, portalPrevious, settings, begin, velocity);
}
}
private static void _rayEnd(IPortalable placeable, IEnumerable<IPortal> portals, double movementLeft, IPortal portalPrevious, Settings settings, Transform2 begin, Transform2 velocity)
{
begin.Position += velocity.Position.Normalized() * (float)movementLeft;
if (settings.AdjustEndpoint)
{
/*After the end position of the ray has been determined, adjust it's position so that it isn't too close to
* any portal. Otherwise there is a risk of ambiguity as to which side of a portal the end point is on.*/
begin = AddMargin(portals, portalPrevious, begin, velocity);
}
placeable.SetTransform(begin);
}