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Interpolate the closing edge of polygons, geodesic or not #24

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Merged
wf9a5m75 merged 2 commits into from
Nov 8, 2026
Merged

Interpolate the closing edge of polygons, geodesic or not #24

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1661e81
Interpolate the closing edge of geodesic polygons
wf9a5m75 Nov 8, 2026
cd15df6
Densify the closing edge of non-geodesic polygons too
wf9a5m75 Nov 8, 2026
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11 changes: 7 additions & 4 deletions src/main/java/com/mapconductor/googlemaps/polygon/GoogleMapPolygonOverlayRenderer.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -6,12 +6,11 @@ import com.google.android.gms.maps.model.PolygonOptions
import com.mapconductor.core.ResourceProvider
import com.mapconductor.core.features.GeoPoint
import com.mapconductor.core.features.GeoPointInterface
import com.mapconductor.core.geometry.densifyPolygonRing
import com.mapconductor.core.polygon.AbstractPolygonOverlayRenderer
import com.mapconductor.core.polygon.PolygonEntityInterface
import com.mapconductor.core.polygon.PolygonState
import com.mapconductor.core.polygon.unionHoles
import com.mapconductor.core.spherical.Planar
import com.mapconductor.core.spherical.WGS84Geodesic
import com.mapconductor.googlemaps.AdaptiveInterpolation
import com.mapconductor.googlemaps.GoogleMapActualPolygon
import com.mapconductor.googlemaps.GoogleMapViewHolder
Expand Down Expand Up @@ -42,7 +41,9 @@ internal class GoogleMapPolygonOverlayRenderer(
val key = AdaptiveInterpolation.cacheKey(AdaptiveInterpolation.pointsHash(statePoints), maxSegmentLength)
interpolationCache.get(key)?.let { return it }

val geoPoints = WGS84Geodesic.createInterpolatePoints(statePoints, maxSegmentLength = maxSegmentLength)
// リングの閉じる辺（末尾 → 先頭）も大圏で補間する。隣り合う点の間だけを補間すると、閉じる辺が
// 直線の弦になり、塗りも輪郭（同じネイティブポリゴンの stroke）もそこだけ直線になる。
val geoPoints = densifyPolygonRing(statePoints, geodesic = true, maxSegmentLength = maxSegmentLength)
val points = geoPoints.map { GeoPoint.from(it).toLatLng() }
interpolationCache.put(key, points)
return points
Expand All @@ -54,7 +55,9 @@ internal class GoogleMapPolygonOverlayRenderer(
): List<LatLng> =
when (geodesic) {
true -> geodesicPoints(statePoints)
false -> Planar.createInterpolatePoints(statePoints).map { GeoPoint.from(it).toLatLng() }
// geodesic=false も閉じる辺を緯度経度で線形補間する（輪郭のポリラインと同じ線。補間しないと
// 閉じる辺だけメルカトルの直線になる）。
false -> densifyPolygonRing(statePoints, geodesic = false).map { GeoPoint.from(it).toLatLng() }
}

private fun toLatLngHoles(
Expand Down
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