From e2969c7168474132caad95779439e050d75af343 Mon Sep 17 00:00:00 2001
From: Daniel Allen <daniel.allen@trakkasystems.com>
Date: Mon, 25 Sep 2023 20:59:39 -0700
Subject: [PATCH] Added option of allowing multi-touch drag in combination with
 pinch/twist gestures. This feels more natural if you allow multi-touch-drag
 to be pan or drag.

---
 src/osgEarth/EarthManipulator     |  5 +++++
 src/osgEarth/EarthManipulator.cpp | 19 +++++++++++++------
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/src/osgEarth/EarthManipulator b/src/osgEarth/EarthManipulator
index fc8d0fee5b..ee42efbd36 100644
--- a/src/osgEarth/EarthManipulator
+++ b/src/osgEarth/EarthManipulator
@@ -514,6 +514,10 @@ namespace osgEarth { namespace Util
             void setZoomToMouse(bool value) { _zoomToMouse = value; }
             bool getZoomToMouse() const { return _zoomToMouse; }
 
+            /** Allow multitouch drag events to be combined with pinch/twist in the same gesture */
+            void setAllowTouchDragCombos(bool value) { _allowTouchDragCombos = value; }
+            bool getAllowTouchDragCombos() const { return _allowTouchDragCombos; }
+
         private:
 
             friend class EarthManipulator;
@@ -561,6 +565,7 @@ namespace osgEarth { namespace Util
             double _throwDecayRate;
 
             bool _zoomToMouse;
+            bool _allowTouchDragCombos;
         };
 
     public:
diff --git a/src/osgEarth/EarthManipulator.cpp b/src/osgEarth/EarthManipulator.cpp
index 0aa6c888f6..0ea433a3fc 100644
--- a/src/osgEarth/EarthManipulator.cpp
+++ b/src/osgEarth/EarthManipulator.cpp
@@ -297,7 +297,8 @@ _terrainAvoidanceEnabled        ( true ),
 _terrainAvoidanceMinDistance    ( 1.0 ),
 _throwingEnabled                ( false ),
 _throwDecayRate                 ( 0.05 ),
-_zoomToMouse                    ( false )
+_zoomToMouse                    ( false ),
+_allowTouchDragCombos           ( false )
 {
     //NOP
 }
@@ -329,7 +330,8 @@ _terrainAvoidanceEnabled( rhs._terrainAvoidanceEnabled ),
 _terrainAvoidanceMinDistance( rhs._terrainAvoidanceMinDistance ),
 _throwingEnabled( rhs._throwingEnabled ),
 _throwDecayRate( rhs._throwDecayRate ),
-_zoomToMouse( rhs._zoomToMouse )
+_zoomToMouse( rhs._zoomToMouse ),
+_allowTouchDragCombos( rhs._allowTouchDragCombos )
 {
     //NOP
 }
@@ -2188,10 +2190,13 @@ EarthManipulator::parseTouchEvents( TouchEvents& output )
 
         // Threshold in pixels for determining if a two finger drag happened.
         float dragThres = 1.0f;
+        bool doMultiDrag = ( osg::equivalent(vec0.x(), vec1.x(), dragThres) &&
+                             osg::equivalent(vec0.y(), vec1.y(), dragThres) ) ||
+                           _settings->getAllowTouchDragCombos();
 
-        // now see if that corresponds to any touch events:
-        if (osg::equivalent(vec0.x(), vec1.x(), dragThres) &&
-            osg::equivalent(vec0.y(), vec1.y(), dragThres))
+        // First check if we should be doing the multidrag event, either because
+        // it was a pure drag, or because we allow it in combination with pinch/twise
+        if( doMultiDrag )
         {
             // two-finger drag.
             output.push_back(TouchEvent());
@@ -2200,7 +2205,9 @@ EarthManipulator::parseTouchEvents( TouchEvents& output )
             ev._dx = 0.5 * (dx[0] + dx[1]) * sens;
             ev._dy = 0.5 * (dy[0] + dy[1]) * sens;
         }
-        else
+
+        // If it wasn't a drag event, or if we allow drag combinations, do the pinch/twist
+        if( !doMultiDrag || _settings->getAllowTouchDragCombos() )
         {
             // otherwise it's a pinch and/or a zoom.  You can do them together.
             if (fabs(deltaDistance) > (1.0 * 0.0005 / sens))