invert x and y for rotation

jillesvangurp · Oct 19, 2021 · 49eb2d3 · 49eb2d3
1 parent 569d6d8
commit 49eb2d3
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Showing 2 changed files with 4 additions and 4 deletions.
diff --git a/src/commonMain/kotlin/com/jillesvangurp/geo/GeoGeometry.kt b/src/commonMain/kotlin/com/jillesvangurp/geo/GeoGeometry.kt
@@ -863,8 +863,8 @@ class GeoGeometry {
 
             // basic high school math: given an angle in radians and a distance, calculate x and y ...
             val angle = toRadians((heading + degrees) % 360)
-            val x = cos(angle) * distance
-            val y = sin(angle) * distance
+            val x = sin(angle) * distance
+            val y = cos(angle) * distance
 
             // use the x and y to translate the anchor and get the point on the circle
             return GeoGeometry.translate(anchor.latitude, anchor.longitude, y, x)

diff --git a/src/commonTest/kotlin/com/jillesvangurp/geogeometry/GeoGeometryTest.kt b/src/commonTest/kotlin/com/jillesvangurp/geogeometry/GeoGeometryTest.kt
@@ -120,8 +120,8 @@ class GeoGeometryTest {
     fun rotateByZeroDegreesShouldBeSamePoint() {
         val anchor = bergstr16Berlin
         val point = oranienburgerTor
-        GeoGeometry.distance(point, GeoGeometry.rotateAround(anchor, point, 0.0)) shouldBeLessThan 100.0
-        (GeoGeometry.distance(point, GeoGeometry.rotateAround(anchor, point, 180.0)) - 2*GeoGeometry.distance(anchor,point)).absoluteValue shouldBeLessThan 100.0
+        GeoGeometry.distance(point, GeoGeometry.rotateAround(anchor, point, 0.0)) shouldBeLessThan 1.0
+        (GeoGeometry.distance(point, GeoGeometry.rotateAround(anchor, point, 180.0)) - 2*GeoGeometry.distance(anchor,point)).absoluteValue shouldBeLessThan 1.0
     }
 
     @Test