private List <PointDouble> ClipToBounds(Rectangle bounds)
{
var points = new List <PointDouble>();
int n = _edges.Count;
int i = 0;
Edge edge;
while (i < n && (!_edges[i].IsVisible))
{
++i;
}
if (i == n)
{
// no edges visible
return(new List <PointDouble>());
}
edge = _edges[i];
LR orientation = _edgeOrientations[i];
points.Add(edge.ClippedEnds[orientation]);
points.Add(edge.ClippedEnds[orientation.other()]);
for (int j = i + 1; j < n; ++j)
{
edge = _edges[j];
if (!edge.IsVisible)
{
continue;
}
Connect(points, j, bounds, false);
}
// close up the polygon by adding another corner point of the bounds if needed:
Connect(points, i, bounds, true);
return(points);
}
private void Connect(List <PointDouble> points, int j, Rectangle bounds, bool closingUp)
{
PointDouble rightPoint = points[points.Count - 1];
Edge newEdge = _edges[j];
LR newOrientation = _edgeOrientations[j];
// the point that must be connected to rightPoint:
PointDouble newPoint = newEdge.ClippedEnds[newOrientation];
if (!CloseEnough(rightPoint, newPoint))
{
// The points do not coincide, so they must have been clipped at the bounds;
// see if they are on the same border of the bounds:
if (rightPoint.X != newPoint.X &&
rightPoint.Y != newPoint.Y)
{
// They are on different borders of the bounds;
// insert one or two corners of bounds as needed to hook them up:
// (NOTE this will not be correct if the region should take up more than
// half of the bounds rect, for then we will have gone the wrong way
// around the bounds and included the smaller part rather than the larger)
int rightCheck = BoundsCheck.Check(rightPoint, bounds);
int newCheck = BoundsCheck.Check(newPoint, bounds);
double px, py;
if ((rightCheck & BoundsCheck.RIGHT) != 0)
{
px = bounds.right;
if ((newCheck & BoundsCheck.BOTTOM) != 0)
{
py = bounds.bottom;
points.Add(new PointDouble(px, py));
}
else if ((newCheck & BoundsCheck.TOP) != 0)
{
py = bounds.top;
points.Add(new PointDouble(px, py));
}
else if ((newCheck & BoundsCheck.LEFT) != 0)
{
if (rightPoint.Y - bounds.y + newPoint.Y - bounds.y < bounds.height)
{
py = bounds.top;
}
else
{
py = bounds.bottom;
}
points.Add(new PointDouble(px, py));
points.Add(new PointDouble(bounds.left, py));
}
}
else if ((rightCheck & BoundsCheck.LEFT) != 0)
{
px = bounds.left;
if ((newCheck & BoundsCheck.BOTTOM) != 0)
{
py = bounds.bottom;
points.Add(new PointDouble(px, py));
}
else if ((newCheck & BoundsCheck.TOP) != 0)
{
py = bounds.top;
points.Add(new PointDouble(px, py));
}
else if ((newCheck & BoundsCheck.RIGHT) != 0)
{
if (rightPoint.Y - bounds.y + newPoint.Y - bounds.y < bounds.height)
{
py = bounds.top;
}
else
{
py = bounds.bottom;
}
points.Add(new PointDouble(px, py));
points.Add(new PointDouble(bounds.right, py));
}
}
else if ((rightCheck & BoundsCheck.TOP) != 0)
{
py = bounds.top;
if ((newCheck & BoundsCheck.RIGHT) != 0)
{
px = bounds.right;
points.Add(new PointDouble(px, py));
}
else if ((newCheck & BoundsCheck.LEFT) != 0)
{
px = bounds.left;
points.Add(new PointDouble(px, py));
}
else if ((newCheck & BoundsCheck.BOTTOM) != 0)
{
if (rightPoint.X - bounds.x + newPoint.X - bounds.x < bounds.width)
{
px = bounds.left;
}
else
{
px = bounds.right;
}
points.Add(new PointDouble(px, py));
points.Add(new PointDouble(px, bounds.bottom));
}
}
else if ((rightCheck & BoundsCheck.BOTTOM) != 0)
{
py = bounds.bottom;
if ((newCheck & BoundsCheck.RIGHT) != 0)
{
px = bounds.right;
points.Add(new PointDouble(px, py));
}
else if ((newCheck & BoundsCheck.LEFT) != 0)
{
px = bounds.left;
points.Add(new PointDouble(px, py));
}
else if ((newCheck & BoundsCheck.TOP) != 0)
{
if (rightPoint.X - bounds.x + newPoint.X - bounds.x < bounds.width)
{
px = bounds.left;
}
else
{
px = bounds.right;
}
points.Add(new PointDouble(px, py));
points.Add(new PointDouble(px, bounds.top));
}
}
}
if (closingUp)
{
// newEdge's ends have already been added
return;
}
points.Add(newPoint);
}
var newRightPoint = newEdge.ClippedEnds[newOrientation.other()];
if (!CloseEnough(points[0], newRightPoint))
{
points.Add(newRightPoint);
}
}
