private static List <Vertices> Execute(Vertices subject, Vertices clip, PolyClipType clipType, out PolyClipError error)
{
Debug.Assert(subject.IsSimple() && clip.IsSimple(), "Non simple input!", "Input polygons must be simple (cannot intersect themselves).");
Vertices vertices;
Vertices vertices2;
YuPengClipper.CalculateIntersections(subject, clip, out vertices, out vertices2);
TSVector2 lowerBound = subject.GetAABB().LowerBound;
TSVector2 lowerBound2 = clip.GetAABB().LowerBound;
TSVector2 tSVector;
TSVector2.Min(ref lowerBound, ref lowerBound2, out tSVector);
tSVector = TSVector2.one - tSVector;
bool flag = tSVector != TSVector2.zero;
if (flag)
{
vertices.Translate(ref tSVector);
vertices2.Translate(ref tSVector);
}
vertices.ForceCounterClockWise();
vertices2.ForceCounterClockWise();
List <FP> poly1Coeff;
List <YuPengClipper.Edge> poly1Simplicies;
YuPengClipper.CalculateSimplicalChain(vertices, out poly1Coeff, out poly1Simplicies);
List <FP> poly2Coeff;
List <YuPengClipper.Edge> poly2Simplicies;
YuPengClipper.CalculateSimplicalChain(vertices2, out poly2Coeff, out poly2Simplicies);
List <YuPengClipper.Edge> simplicies;
YuPengClipper.CalculateResultChain(poly1Coeff, poly1Simplicies, poly2Coeff, poly2Simplicies, clipType, out simplicies);
List <Vertices> list;
error = YuPengClipper.BuildPolygonsFromChain(simplicies, out list);
tSVector *= -1f;
for (int i = 0; i < list.Count; i++)
{
list[i].Translate(ref tSVector);
SimplifyTools.CollinearSimplify(list[i], FP.Zero);
}
return(list);
}
/// <summary>
/// Implements "A new algorithm for Boolean operations on general polygons"
/// available here: http://liama.ia.ac.cn/wiki/_media/user:dong:dong_cg_05.pdf
/// Merges two polygons, a subject and a clip with the specified operation. Polygons may not be
/// self-intersecting.
///
/// Warning: May yield incorrect results or even crash if polygons contain collinear points.
/// </summary>
/// <param name="subject">The subject polygon.</param>
/// <param name="clip">The clip polygon, which is added,
/// substracted or intersected with the subject</param>
/// <param name="clipType">The operation to be performed. Either
/// Union, Difference or Intersection.</param>
/// <param name="error">The error generated (if any)</param>
/// <returns>A list of closed polygons, which make up the result of the clipping operation.
/// Outer contours are ordered counter clockwise, holes are ordered clockwise.</returns>
private static List <Vertices> Execute(Vertices subject, Vertices clip, PolyClipType clipType, out PolyClipError error)
{
Debug.Assert(subject.IsSimple() && clip.IsSimple(), "Non simple input!", "Input polygons must be simple (cannot intersect themselves).");
// Copy polygons
Vertices slicedSubject;
Vertices slicedClip;
// Calculate the intersection and touch points between
// subject and clip and add them to both
CalculateIntersections(subject, clip, out slicedSubject, out slicedClip);
// Translate polygons into upper right quadrant
// as the algorithm depends on it
TSVector2 lbSubject = subject.GetAABB().LowerBound;
TSVector2 lbClip = clip.GetAABB().LowerBound;
TSVector2 translate;
TSVector2.Min(ref lbSubject, ref lbClip, out translate);
translate = TSVector2.one - translate;
if (translate != TSVector2.zero)
{
slicedSubject.Translate(ref translate);
slicedClip.Translate(ref translate);
}
// Enforce counterclockwise contours
slicedSubject.ForceCounterClockWise();
slicedClip.ForceCounterClockWise();
List <Edge> subjectSimplices;
List <FP> subjectCoeff;
List <Edge> clipSimplices;
List <FP> clipCoeff;
// Build simplical chains from the polygons and calculate the
// the corresponding coefficients
CalculateSimplicalChain(slicedSubject, out subjectCoeff, out subjectSimplices);
CalculateSimplicalChain(slicedClip, out clipCoeff, out clipSimplices);
List <Edge> resultSimplices;
// Determine the characteristics function for all non-original edges
// in subject and clip simplical chain and combine the edges contributing
// to the result, depending on the clipType
CalculateResultChain(subjectCoeff, subjectSimplices, clipCoeff, clipSimplices, clipType,
out resultSimplices);
List <Vertices> result;
// Convert result chain back to polygon(s)
error = BuildPolygonsFromChain(resultSimplices, out result);
// Reverse the polygon translation from the beginning
// and remove collinear points from output
translate *= -1f;
for (int i = 0; i < result.Count; ++i)
{
result[i].Translate(ref translate);
SimplifyTools.CollinearSimplify(result[i], FP.Zero);
}
return(result);
}
