improve floating point issues

streetcomplete · Jul 19, 2023 · 8c6b138 · 8c6b138
1 parent 5646ea1
commit 8c6b138
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/app/src/main/java/de/westnordost/streetcomplete/data/download/tiles/TilesRect.kt b/app/src/main/java/de/westnordost/streetcomplete/data/download/tiles/TilesRect.kt
@@ -7,6 +7,8 @@ import kotlinx.serialization.Serializable
 import kotlin.math.PI
 import kotlin.math.asinh
 import kotlin.math.atan
+import kotlin.math.nextDown
+import kotlin.math.nextUp
 import kotlin.math.sinh
 import kotlin.math.tan
 
@@ -114,12 +116,12 @@ private fun tile2lon(x: Int, zoom: Int): Double =
     360.0 * x / numTiles(zoom).toDouble() - 180.0
 
 private fun tile2lat(y: Int, zoom: Int): Double =
-    180.0 * atan(sinh(PI * (1.0 - 2.0 * y / numTiles(zoom)))) / PI
+    (180.0 / PI * atan(sinh(PI * (1.0 - 2.0 * y / numTiles(zoom))))).nextDown()
 
 private fun lon2tile(lon: Double, zoom: Int): Int =
     (numTiles(zoom) * (lon + 180.0) / 360.0).toInt()
 
 private fun lat2tile(lat: Double, zoom: Int): Int =
-    (numTiles(zoom) * (1.0 - asinh(tan(PI * lat / 180.0)) / PI) / 2.0).toInt()
+    (numTiles(zoom) * (1.0 - asinh(tan(PI * lat / 180.0)) / PI) / 2.0).nextUp().toInt()
 
 private fun numTiles(zoom: Int): Int = 1 shl zoom