public override KeyValuePair <double, Handle> GetSelectionDistance(SysPoint point)
{
double distance;
if (!ShouldRender)
{
distance = double.NaN;
}
else
{
BoardPoint boardPoint = Board.GetBoardPoint(point);
BoardPoint observerPosition = GetEffectiveObserverPosition();
Line2 bearingLine = new Line2(observerPosition, new Vector2(0, 1).Rotate(-Bearing));
distance = Math.Abs(bearingLine.DistanceTo(boardPoint)) * Board.ZoomFactor;
// the distance measurement considers the entire infinite line, but we only want to consider the ray starting from the observer, so
// we'll ignore the portion of the line on the other side of the observer point
if (distance > 4 || bearingLine.ClosestPointOnSegment(boardPoint) == bearingLine.Start &&
boardPoint.DistanceTo(bearingLine.Start) * Board.ZoomFactor > 4)
{
distance = double.NaN;
}
}
return(new KeyValuePair <double, Handle>(distance, null));
}
public override void Render(Graphics graphics)
{
if (ShouldRender)
{
BoardPoint observerPosition = GetEffectiveObserverPosition();
observerPosition = new BoardPoint(observerPosition.X * Board.ZoomFactor, -observerPosition.Y * Board.ZoomFactor);
Vector2 screenVector = new Vector2(0, -1).Rotate(Bearing);
Line2 bearingLine = new Line2(observerPosition, screenVector);
// since the bearing line is infinitely long, we'll test the intersection of the line against all four sides of the clipping
// rectangle, and draw the line to the furthest intersection
BoardRect clipRect = new BoardRect(graphics.VisibleClipBounds);
BoardPoint endPoint = BoardPoint.Invalid;
double maxDistance = 0;
for (int i = 0; i < 4; i++)
{
Line2 edge = clipRect.GetEdge(i);
LineIntersection intersection = bearingLine.GetIntersectionInfo(edge);
if (intersection.OnSecond)
{
double distance = observerPosition.DistanceTo(intersection.Point);
// find the closest point on the segment to ensure that we're only considering intersections in the forward direction of the
// vector
if (distance > maxDistance && bearingLine.ClosestPointOnSegment(intersection.Point) != bearingLine.Start)
{
endPoint = intersection.Point;
maxDistance = distance;
}
}
}
if (endPoint.IsValid)
{
graphics.DrawLine(Pen, observerPosition.ToPointF(), endPoint.ToPointF());
graphics.DrawCircle(Pen, observerPosition.ToPointF(), 3);
RenderTime(graphics, (observerPosition + (endPoint - observerPosition) * 0.5).ToPointF());
}
}
}
