Fix/placemark rotation and tilt

worldwind-examples/src/main/java/gov/nasa/worldwindx/PlacemarksMilStd2525Activity.java

@@ -86,6 +86,7 @@ protected void onPostExecute(Void notUsed) {
             Placemark drone = new Placemark(
                 Position.fromDegrees(32.4520, 63.44553, 3000),
                 MilStd2525.getPlacemarkAttributes("SFAPMFQM--GIUSA", modifiers, null));
+            drone.getAttributes().setDrawLeader(true);
 
             symbolLayer.addRenderable(drone);
 
@@ -96,6 +97,7 @@ protected void onPostExecute(Void notUsed) {
             Placemark launcher = new Placemark(
                 Position.fromDegrees(32.4014, 63.3894, 0),
                 MilStd2525.getPlacemarkAttributes("SHGXUCFRMS----G", modifiers, null));
+            launcher.setAltitudeMode(WorldWind.CLAMP_TO_GROUND);
 
             symbolLayer.addRenderable(launcher);
 
@@ -109,6 +111,7 @@ protected void onPostExecute(Void notUsed) {
             Placemark machineGun = new Placemark(
                 Position.fromDegrees(32.3902, 63.4161, 0),
                 MilStd2525.getPlacemarkAttributes("SFGPEWRH--MTUSG", modifiers, null));
+            machineGun.setAltitudeMode(WorldWind.CLAMP_TO_GROUND);
 
             symbolLayer.addRenderable(machineGun);
 

worldwind-examples/src/main/java/gov/nasa/worldwindx/milstd2525/MilStd2525.java

@@ -269,7 +269,8 @@ public Bitmap createBitmap() {
             Rect bounds = imageInfo.getImageBounds();       // The extents of the image, including text modifiers
             this.placemarkOffset = new Offset(
                 WorldWind.OFFSET_PIXELS, centerPoint.x, // x offset
-                WorldWind.OFFSET_PIXELS, bounds.height() - centerPoint.y); // y offset converted to lower-left origin
+                // Use billboarding or lollipopping to prevent icon clipping by terrain as described in MIL-STD-2525C APPENDIX F.5.1.1.2
+                WorldWind.OFFSET_PIXELS, 0/*bounds.height() - centerPoint.y*/); // y offset converted to lower-left origin
 
             // Apply the placemark offset to the attributes on the main thread. This is necessary to synchronize write
             // access to placemarkAttributes from the thread that invokes this BitmapFactory and read access from the

worldwind/src/main/java/gov/nasa/worldwind/shape/Placemark.java

@@ -60,7 +60,7 @@ public interface LevelOfDetailSelector {
      */
     protected static final double DEFAULT_EYE_DISTANCE_SCALING_THRESHOLD = 1e6;
 
-    protected static final double DEFAULT_DEPTH_OFFSET = -0.1;
+    protected static final double DEFAULT_DEPTH_OFFSET = -0.03;
 
     private static Vec3 placePoint = new Vec3();
 
@@ -684,8 +684,9 @@ protected void doRender(RenderContext rc) {
 
         // Compute a screen depth offset appropriate for the current viewing parameters.
         double depthOffset = 0;
-        if (this.cameraDistance < rc.horizonDistance) {
-            depthOffset = DEFAULT_DEPTH_OFFSET;
+        double absTilt = Math.abs( rc.camera.tilt );
+        if (this.cameraDistance < rc.horizonDistance && absTilt <= 90) {
+            depthOffset = ( 1 - absTilt / 90 ) * DEFAULT_DEPTH_OFFSET;
         }
 
         // Project the placemark's model point to screen coordinates, using the screen depth offset to push the screen
@@ -808,48 +809,56 @@ protected void determineActiveTexture(RenderContext rc) {
         // offset is defined with its origin at the image's bottom-left corner and axes that extend up and to the right
         // from the origin point. When the placemark has no active texture the image scale defines the image size and no
         // other scaling is applied.
+        double offsetX, offsetY, scaleX, scaleY;
         if (this.activeTexture != null) {
             int w = this.activeTexture.getWidth();
             int h = this.activeTexture.getHeight();
             double s = this.activeAttributes.imageScale * visibilityScale;
             this.activeAttributes.imageOffset.offsetForSize(w, h, offset);
-
-            unitSquareTransform.multiplyByTranslation(
-                screenPlacePoint.x - offset.x * s,
-                screenPlacePoint.y - offset.y * s,
-                screenPlacePoint.z);
-
-            unitSquareTransform.multiplyByScale(w * s, h * s, 1);
+            offsetX = offset.x * s;
+            offsetY = offset.y * s;
+            scaleX = w * s;
+            scaleY = h * s;
         } else {
             // This branch serves both non-textured attributes and also textures that haven't been loaded yet.
             // We set the size for non-loaded textures to the typical size of a contemporary "small" icon (24px)
             double size = this.activeAttributes.imageSource != null ? 24 : this.activeAttributes.imageScale;
             size *= visibilityScale;
             this.activeAttributes.imageOffset.offsetForSize(size, size, offset);
+            offsetX = offset.x;
+            offsetY = offset.y;
+            scaleX = scaleY = size;
+        }
 
-            unitSquareTransform.multiplyByTranslation(
-                screenPlacePoint.x - offset.x,
-                screenPlacePoint.y - offset.y,
+        // Position image on screen
+        unitSquareTransform.multiplyByTranslation(
+                screenPlacePoint.x,
+                screenPlacePoint.y,
                 screenPlacePoint.z);
 
-            unitSquareTransform.multiplyByScale(size, size, 1);
+        // Divide Z by 2^24 to prevent texture clipping when tilting (where 24 is depth buffer bit size).
+        // Doing so will limit depth range to (diagonal length)/2^24 and make its value within 0..1 range.
+        unitSquareTransform.multiplyByScale(1, 1, 1d / (1 << 24) );
+
+        // Perform the tilt so that the image tilts back from its base into the view volume
+        if (this.imageTilt != 0) {
+            double tilt = this.imageTiltReference == WorldWind.RELATIVE_TO_GLOBE ?
+                    rc.camera.tilt + this.imageTilt : this.imageTilt;
+            unitSquareTransform.multiplyByRotation(-1, 0, 0, tilt);
         }
 
-        // ... perform image rotation
+        // Perform image rotation
         if (this.imageRotation != 0) {
             double rotation = this.imageRotationReference == WorldWind.RELATIVE_TO_GLOBE ?
-                rc.camera.heading - this.imageRotation : -this.imageRotation;
-            unitSquareTransform.multiplyByTranslation(0.5, 0.5, 0);
+                    rc.camera.heading - this.imageRotation : -this.imageRotation;
             unitSquareTransform.multiplyByRotation(0, 0, 1, rotation);
-            unitSquareTransform.multiplyByTranslation(-0.5, -0.5, 0);
         }
 
-        // ... and perform the tilt so that the image tilts back from its base into the view volume.
-        if (this.imageTilt != 0) {
-            double tilt = this.imageTiltReference == WorldWind.RELATIVE_TO_GLOBE ?
-                rc.camera.tilt + this.imageTilt : this.imageTilt;
-            unitSquareTransform.multiplyByRotation(-1, 0, 0, tilt);
-        }
+        // Apply pivot translation
+        unitSquareTransform.multiplyByTranslation(-offsetX, -offsetY, 0);
+
+        // Apply scale
+        unitSquareTransform.multiplyByScale(scaleX, scaleY, 1);
     }
 
     /**