private static LinkedList <Circle> InitFrontchain(UiInnerNode node)
{
var frontChain = new LinkedList <Circle>();
if (node.Children.Count == 0)
{
return(frontChain);
}
var c1 = node.Children[0].Circle;
frontChain.AddLast(c1);
if (node.Children.Count == 1)
{
return(frontChain);
}
var c2 = node.Children[1].Circle;
c2.Position.Value = TreeGeometry.CalcTangentCircleCenter(c1.Position.Value, c1.Radius,
c2.Radius,
TreeGeometry.GetRandomAngle());
frontChain.AddLast(c2);
return(frontChain);
}
/// <summary>
/// From Wang's circle packing algorithm, see "Visualization of large hierarchical data by circle packing"
/// </summary>
/// <param name="innerNode"></param>
internal LinkedList <Circle> CirclePacking(UiInnerNode innerNode)
{
var frontChain = InitFrontchain(innerNode);
for (var i = 2; i < innerNode.Children.Count; i++)
{
// circle with minimal distance to origin
var tangentCircle1 = GetClosestFromOrigin(frontChain);
// circle after tangent circle 1
var tangentCircle2 = tangentCircle1.Next();
// circle of current inner node, claculate potential position
var currentCircleRad = innerNode.Children[i].Circle.Radius;
var currentCirclePos = TreeGeometry.CalcTangentCircleCenter(tangentCircle1.Value.Position.Value,
tangentCircle2.Value.Position.Value, tangentCircle1.Value.Radius, tangentCircle2.Value.Radius,
currentCircleRad);
// circle that intersects current circle
var intersectingCircle = GetIntersectingCircle(frontChain, currentCirclePos, currentCircleRad);
// No intersection, place current circle
if (intersectingCircle == null)
{
innerNode.Children[i].Circle.Position.Value = currentCirclePos;
frontChain.AddBefore(tangentCircle2, innerNode.Children[i].Circle);
continue;
}
// Delete old circles from front chain
if (intersectingCircle.IsAfter(tangentCircle2))
{
tangentCircle1.DeleteAfterUntil(intersectingCircle);
}
else
{
intersectingCircle.DeleteAfterUntil(tangentCircle2);
}
// Proceed with current circle again, position is calculated according to updated front chain
i--;
}
innerNode.Circle.Radius = GetEnclosingRadius(frontChain);
return(frontChain);
}