Allow specifying altitude offset

Author: ma2yama

three.js/examples/location-based/index.js

@@ -11,7 +11,8 @@ function main() {
     const geom = new THREE.BoxGeometry(20,20,20);
 
     const useAltitude = false;
-    const arjs = new LocationBased(scene, camera, { useAltitude });
+    const altitudeOffset = 0;
+    const arjs = new LocationBased(scene, camera, { useAltitude, altitudeOffset });
 
     // You can change the minimum GPS accuracy needed to register a position - by default 1000m
     //const arjs = new LocationBased(scene, camera, { gpsMinAccuracy: 30 } );

three.js/src/location-based/js/location-based.js

@@ -25,6 +25,7 @@ class LocationBased {
       options.initialPositionAsOrigin ||
       false;
     this.useAltitude = options.useAltitude || false;
+    this.altitudeOffset = options.altitudeOffset || 0;
   }
 
   setProjection(proj) {
@@ -154,7 +155,7 @@ class LocationBased {
           position.coords.longitude,
           position.coords.latitude,
           this.useAltitude && position.coords.altitude != null
-            ? position.coords.altitude
+            ? position.coords.altitude + this.altitudeOffset
             : undefined,
         );