API Reference > geometry-core > Curve > RegionOps > polygonXYAreaUnionLoopsToPolyface polygonXYAreaUnionLoopsToPolyface MethodStatic return a polyface containing the area union of two XY regions. Within each region, in and out is determined by parity rules. Any face that is an odd number of crossings from the far outside is IN Any face that is an even number of crossings from the far outside is OUT polygonXYAreaUnionLoopsToPolyface(loopsA: MultiLineStringDataVariant, loopsB: MultiLineStringDataVariant, triangulate: boolean = false): undefined | Polyface Parameter Type Description loopsA MultiLineStringDataVariant first set of loops loopsB MultiLineStringDataVariant second set of loops triangulate boolean Returns - undefined | Polyface Defined in curve/RegionOps.ts Line 221 Last Updated: 12 June, 2024