private InsetVertex CombineVectorLines(InsetVertex prev, InsetVertex next, double thickness)
{
var prevLine = new LineF(prev.Previous, prev.Outer);
var nextLine = new LineF(next.Outer, next.Next);
var newOuter = prevLine.Intersect(nextLine);
return(new InsetVertex(newOuter, prev.Previous, next.Next, thickness));
}
private bool DoesIntersect(InsetVertex one, InsetVertex two)
{
return(!IsSameSign(Cross(one.Inner - one.Outer, two.Outer - one.Inner), Cross(one.Inner - one.Outer, two.Inner - one.Inner)) &&
!IsSameSign(Cross(two.Inner - two.Outer, one.Outer - two.Inner), Cross(two.Inner - two.Outer, one.Inner - two.Inner)));
}
private int PopulatePolyStorage(List <Vector2> polygon, double thickness = 0)
{
if (polygon.Count < 3)
{
return(0);
}
if (_polyStorage == null || _polyStorage.Length < polygon.Count)
{
_polyStorage = new InsetVertex[polygon.Count];
}
if (Math.Abs(thickness) < _doubleCheckCushion)
{
for (var i = 0; i < polygon.Count; i++)
{
_polyStorage[i] = new InsetVertex(polygon[i]);
}
return(polygon.Count);
}
var storageLength = 0;
for (var i = 0; i < polygon.Count; i++)
{
var current = polygon[i];
var prevPoint = polygon[(i - 1 + polygon.Count) % polygon.Count];
var nextPoint = polygon[(i + 1) % polygon.Count];
var lineToInner = new InsetVertex(current, prevPoint, nextPoint, thickness);
if (storageLength > 0 && thickness > 0 && DoesIntersect(_polyStorage[storageLength - 1], lineToInner))
{
_polyStorage[storageLength - 1] = CombineVectorLines(_polyStorage[storageLength - 1], lineToInner, thickness);
}
else
{
_polyStorage[storageLength] = lineToInner;
storageLength += 1;
}
}
if (thickness > 0)
{
var numInvalidated = 0;
for (var i = 0; i < storageLength; i++)
{
var current = _polyStorage[i];
var prevIndex = (i - 1 + storageLength) % storageLength;
var prev = _polyStorage[prevIndex];
if (DoesIntersect(prev, current))
{
_polyStorage[i] = CombineVectorLines(prev, current, thickness);
// Optimizing for the most common case
if (prevIndex == 0)
{
storageLength -= 1;
}
else
{
_polyStorage[prevIndex] = new InsetVertex(Vector2.Zero, false);
numInvalidated += 1;
}
}
else
{
break;
}
}
if (storageLength - numInvalidated < 3)
{
return(0);
}
if (numInvalidated > 0)
{
for (var i = 0; i < storageLength; i++)
{
if (!_polyStorage[i].IsValid)
{
for (var j = i + 1; j < storageLength; j++)
{
_polyStorage[j - 1] = _polyStorage[j];
}
storageLength -= 1;
i -= 1;
}
}
}
}
return(storageLength);
}
