Error when creating a Hexagon in React-three globe about three-conic-polygon-geometry HOT 6 OPEN

@lilesper thanks for reaching out.

There's a chance you may have a reverse wound polygon there, so it's filling the outer side of the sphere instead. Could you try and .reverse() the coordinates array to see if you get a different result?

from three-conic-polygon-geometry.

I have a similar issue.
It happens with any JSON generated with https://geojson.io/
but with examples downloaded from https://geojson-maps.ash.ms/, everything works fine

Example JSON:

  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [-289.6875, -2.811371193331128],
            [-291.09375, -20.632784250388013],
            [-285.46875, -29.535229562948444],
            [-271.40625, -34.30714385628803],
            [-255.9375, -36.597889133070204],
            [-236.25, -31.95216223802496],
            [-233.43749999999997, -15.28418511407642],
            [-233.43749999999997, -7.01366792756663],
            [-237.65625, 5.61598581915534],
            [-243.28125, 13.923403897723347],
            [-248.90624999999997, 24.5271348225978],
            [-241.875, 34.30714385628804],
            [-241.875, 50.736455137010665],
            [-250.31250000000003, 54.97761367069628],
            [-289.6875, -2.811371193331128]
          ]
        ]
      }
    }
  ]
}

@lilesper did you manage to solve it?

from three-conic-polygon-geometry.

@lilesper
.reverse() did the trick, but do you know how can we programmatically detect if we are dealing with reverse-wound polygon? I have a bunch of data and some of it is correct so reversing every array messes things up.

from three-conic-polygon-geometry.

Coolbeans, I'll try .reverse() ! thank you

from three-conic-polygon-geometry.

@vasturiano Same problem here. Is there a simple way to get the smaller mesh by area/volume? Something like:

    const coordinates = polygonGeoJson.features[0].geometry.coordinates;
    const cones1 = new ConicPolygonGeometry(coordinates, 0, 49, false, true, false)
    const reversedCoords = [...coordinates]
    reversedCoords[0].reverse();
    const cones2 = new ConicPolygonGeometry(reversedCoords, 0, 49, false, true, false)
    const cones = cones1.getArea() > cones2.getArea() ? cones2 : cones1

I don't find a getArea() method, just a suggestion on how to programatically decide whether to reverse the coords ...

from three-conic-polygon-geometry.

@SimeonRolev calculating the area of a polygon is not a trivial operation, and also shouldn't be the responsibility of this module as it would incur a performance penalty. The best is if the consumer of this module decides or not to do this verification and reversal before the geojson data is input to it.

I'd recomend d3-geo's geoArea as a utility to perform this calculation.

from three-conic-polygon-geometry.