Skip camera surface collision check if altitude is above Everest.

Author: EMaksymenko

worldwind-tutorials/src/main/assets/camera_control_tutorial.html

@@ -37,6 +37,10 @@ <h3>CameraControlFragment.java</h3>
     <textarea id="java-code">
 public class CameraControlFragment extends BasicGlobeFragment {
 
+    private static final double COLLISION_CHECK_LIMIT = 8848.86; // Everest mountain altitude
+
+    private static final double COLLISION_THRESHOLD = 20.0; // 20m above surface
+
     /**
      * Creates a new WorldWindow object with a custom WorldWindowController.
      */
@@ -62,7 +66,7 @@ <h3>CameraControlFragment.java</h3>
      * A custom WorldWindController that uses gestures to control the camera directly via the setAsCamera interface
      * instead of the default setAsLookAt interface.
      */
-    private class CameraController extends BasicWorldWindowController {
+    private static class CameraController extends BasicWorldWindowController {
 
         protected double beginHeading;
 
@@ -209,21 +213,30 @@ <h3>CameraControlFragment.java</h3>
         }
 
         protected void applyLimits(Camera camera) {
-            double distanceToExtents = this.wwd.distanceToViewGlobeExtents();
+            Position position = camera.position;
 
             double minAltitude = 100;
-            double maxAltitude = distanceToExtents;
-            camera.position.altitude = WWMath.clamp(camera.position.altitude, minAltitude, maxAltitude);
+            double maxAltitude = this.wwd.distanceToViewGlobeExtents();
+            position.altitude = WWMath.clamp(position.altitude, minAltitude, maxAltitude);
+
+            // Check if camera altitude is not under the surface
+            double ve = wwd.getVerticalExaggeration();
+            if (position.altitude < COLLISION_CHECK_LIMIT * ve + COLLISION_THRESHOLD) {
+                double elevation = this.wwd.getGlobe().getElevationAtLocation(position.latitude, position.longitude)
+                        * ve + COLLISION_THRESHOLD;
+                if (elevation > position.altitude) {
+                    position.altitude = elevation;
+                }
+            }
 
             // Limit the tilt to between nadir and the horizon (roughly)
-            double r = wwd.getGlobe().getRadiusAt(camera.position.latitude, camera.position.latitude);
-            double maxTilt = Math.toDegrees(Math.asin(r / (r + camera.position.altitude)));
+            double r = wwd.getGlobe().getRadiusAt(position.latitude, position.latitude);
+            double maxTilt = Math.toDegrees(Math.asin(r / (r + position.altitude)));
             double minTilt = 0;
             camera.tilt = WWMath.clamp(camera.tilt, minTilt, maxTilt);
         }
     }
 }
-
     </textarea>
 </div>
 

worldwind-tutorials/src/main/java/gov/nasa/worldwindx/CameraControlFragment.java

@@ -18,6 +18,8 @@
 
 public class CameraControlFragment extends BasicGlobeFragment {
 
+    private static final double COLLISION_CHECK_LIMIT = 8848.86; // Everest mountain altitude
+
     private static final double COLLISION_THRESHOLD = 20.0; // 20m above surface
 
     /**
@@ -199,10 +201,13 @@ protected void applyLimits(Camera camera) {
             position.altitude = WWMath.clamp(position.altitude, minAltitude, maxAltitude);
 
             // Check if camera altitude is not under the surface
-            double elevation = this.wwd.getGlobe().getElevationAtLocation(position.latitude, position.longitude)
-                    * wwd.getVerticalExaggeration() + COLLISION_THRESHOLD;
-            if (elevation > position.altitude) {
-                position.altitude = elevation;
+            double ve = wwd.getVerticalExaggeration();
+            if (position.altitude < COLLISION_CHECK_LIMIT * ve + COLLISION_THRESHOLD) {
+                double elevation = this.wwd.getGlobe().getElevationAtLocation(position.latitude, position.longitude)
+                        * ve + COLLISION_THRESHOLD;
+                if (elevation > position.altitude) {
+                    position.altitude = elevation;
+                }
             }
 
             // Limit the tilt to between nadir and the horizon (roughly)

worldwind/src/main/java/gov/nasa/worldwind/WorldWindow.java

@@ -56,7 +56,9 @@ public class WorldWindow extends GLSurfaceView implements Choreographer.FrameCal
 
     protected static final int MSG_ID_SET_DEPTH_BITS = 4;
 
-    protected final static double COLLISION_THRESHOLD = 10.0; // 10m above surface
+    protected static final double COLLISION_CHECK_LIMIT = 8848.86; // Everest mountain altitude
+
+    protected static final double COLLISION_THRESHOLD = 10.0; // 10m above surface
 
     /**
      * Planet or celestial object displayed by this WorldWindow.
@@ -451,21 +453,23 @@ public void cameraFromLookAt(LookAt lookAt) {
 
         // Check if camera altitude is not under the surface
         Position position = this.camera.position;
-        double elevation = globe.getElevationAtLocation(position.latitude, position.longitude) * verticalExaggeration + COLLISION_THRESHOLD;
-        if(elevation > position.altitude) {
-            // Set camera altitude above the surface
-            position.altitude = elevation;
-            // Compute new camera point
-            globe.geographicToCartesian(position.latitude, position.longitude, position.altitude, scratchPoint);
-            // Compute look at point
-            globe.geographicToCartesian(lookAt.position.latitude, lookAt.position.longitude, lookAt.position.altitude, scratchRay.origin);
-            // Compute normal to globe in look at point
-            globe.geographicToCartesianNormal(lookAt.position.latitude, lookAt.position.longitude, scratchRay.direction);
-            // Calculate tilt angle between new camera point and look at point
-            scratchPoint.subtract(scratchRay.origin).normalize();
-            double dot = scratchRay.direction.dot(scratchPoint);
-            if (dot >= -1 || dot <= 1) {
-                this.camera.tilt = Math.toDegrees(Math.acos(dot));
+        if (position.altitude < COLLISION_CHECK_LIMIT * verticalExaggeration + COLLISION_THRESHOLD) {
+            double elevation = globe.getElevationAtLocation(position.latitude, position.longitude) * verticalExaggeration + COLLISION_THRESHOLD;
+            if (elevation > position.altitude) {
+                // Set camera altitude above the surface
+                position.altitude = elevation;
+                // Compute new camera point
+                globe.geographicToCartesian(position.latitude, position.longitude, position.altitude, scratchPoint);
+                // Compute look at point
+                globe.geographicToCartesian(lookAt.position.latitude, lookAt.position.longitude, lookAt.position.altitude, scratchRay.origin);
+                // Compute normal to globe in look at point
+                globe.geographicToCartesianNormal(lookAt.position.latitude, lookAt.position.longitude, scratchRay.direction);
+                // Calculate tilt angle between new camera point and look at point
+                scratchPoint.subtract(scratchRay.origin).normalize();
+                double dot = scratchRay.direction.dot(scratchPoint);
+                if (dot >= -1 || dot <= 1) {
+                    this.camera.tilt = Math.toDegrees(Math.acos(dot));
+                }
             }
         }
     }