示例#1
0
        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());
                }
            }
        }