Join Regions

[ahmedshawkey95]

Hi,
Is there any way to allow joining multiple selected regions (not intersected) to generate only one region representing them as shown below?
Input regions:

Required output as one region:

I tried to use the following boolean operation code which is inspired by @_gile 's post, but it only returns the outlining boundary because the inner regions are fully contained inside the outlining region.

 public static Region JoinRegions(List<Region> selectedRegions)
        {
            var boundaryRegion = selectedRegions.First();
            foreach (var region in selectedRegions.Skip(1))
            {
                boundaryRegion.BooleanOperation(BooleanOperationType.BoolUnite, region);
            }

            foreach (var region in selectedRegions.Skip(1))
            {
                //TODO:Join region inside the boundary region
                //boundaryRegion.BooleanOperation(BooleanOperationType.BoolSubtract, region);
            }
            return boundaryRegion;
        }

Thanks in advance.

[_gile · Accepted solution]

Hi,

You have to substract the inner regions to the boundary one.

        public static Region JoinRegions(List<Region> selectedRegions)
        {
            var boundaryRegion = selectedRegions.Aggregate((r1, r2) => r1.Area < r2.Area ? r2 : r1);
            foreach (var region in selectedRegions)
            {
                if (region != boundaryRegion)
                {
                    boundaryRegion.BooleanOperation(BooleanOperationType.BoolSubtract, region);
                }
            }
            return boundaryRegion;
        }

[ahmedshawkey95]

Thanks, @_gile for your valuable help.