From 69aef205af90ed241e3c3593675cd27f81ae16ef Mon Sep 17 00:00:00 2001
From: Kalle Bladin <kallebladin@gmail.com>
Date: Tue, 21 Jun 2016 13:42:56 -0400
Subject: [PATCH] Interaction mode inertia is no longer dependent on the
 framerate.

---
 .../interaction/interactionhandler.h          | 17 +++++++++----
 src/interaction/interactionhandler.cpp        | 24 +++++++++----------
 2 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/include/openspace/interaction/interactionhandler.h b/include/openspace/interaction/interactionhandler.h
index ba3d8a022a..9df40cead8 100644
--- a/include/openspace/interaction/interactionhandler.h
+++ b/include/openspace/interaction/interactionhandler.h
@@ -206,14 +206,15 @@ protected:
         will be updates as soon as it is set to a value (calling the set() function).
     */
     template <typename T, typename ScaleType>
-    class delayedVariable {
+    class DelayedVariable {
     public:
-        delayedVariable(ScaleType scale) {
+        DelayedVariable(ScaleType scale) {
             _scale = scale;
         }
-        void set(T value) {
+        void set(T value, double dt) {
             _targetValue = value;
-            _currentValue = _currentValue + (_targetValue - _currentValue) * _scale;
+            _currentValue = _currentValue + (_targetValue - _currentValue) *
+                min(_scale * dt, 1.0); // less or equal to 1.0 keeps it stable
         }
         T get() {
             return _currentValue;
@@ -229,7 +230,7 @@ protected:
             : velocity(scale)
             , previousPosition(0.0, 0.0) {}
         glm::dvec2 previousPosition;
-        delayedVariable<glm::dvec2, double> velocity;
+        DelayedVariable<glm::dvec2, double> velocity;
     };
 
     std::shared_ptr<InputState> _inputState;
@@ -251,6 +252,12 @@ private:
 class OrbitalInteractionMode : public InteractionMode
 {
 public:
+    /*!
+        \param inputState
+        \param sensitivity
+        \param velocityScalefactor can be set to 60 to remove the inertia of the
+            interaction. Lower value will make it harder to move the camera.
+    */
     OrbitalInteractionMode(
         std::shared_ptr<InputState> inputState,
         double sensitivity,
diff --git a/src/interaction/interactionhandler.cpp b/src/interaction/interactionhandler.cpp
index d0c7dfa78a..700375f524 100644
--- a/src/interaction/interactionhandler.cpp
+++ b/src/interaction/interactionhandler.cpp
@@ -778,44 +778,44 @@ void OrbitalInteractionMode::updateMouseStatesFromInput(double deltaTime) {
         if (keyCtrlPressed) {
             glm::dvec2 mousePositionDelta =
                 _localRotationMouseState.previousPosition - mousePosition;
-            _localRotationMouseState.velocity.set(mousePositionDelta * deltaTime * _sensitivity);
+            _localRotationMouseState.velocity.set(mousePositionDelta * deltaTime * _sensitivity, deltaTime);
 
             _globalRotationMouseState.previousPosition = mousePosition;
-            _globalRotationMouseState.velocity.set(glm::dvec2(0, 0));
+            _globalRotationMouseState.velocity.set(glm::dvec2(0, 0), deltaTime);
         }
         else {
             glm::dvec2 mousePositionDelta =
                 _globalRotationMouseState.previousPosition - mousePosition;
-            _globalRotationMouseState.velocity.set(mousePositionDelta * deltaTime * _sensitivity);
+            _globalRotationMouseState.velocity.set(mousePositionDelta * deltaTime * _sensitivity, deltaTime);
 
             _localRotationMouseState.previousPosition = mousePosition;
-            _localRotationMouseState.velocity.set(glm::dvec2(0, 0));
+            _localRotationMouseState.velocity.set(glm::dvec2(0, 0), deltaTime);
         }
     }
     else { // !button1Pressed
         _localRotationMouseState.previousPosition = mousePosition;
-        _localRotationMouseState.velocity.set(glm::dvec2(0, 0));
+        _localRotationMouseState.velocity.set(glm::dvec2(0, 0), deltaTime);
 
         _globalRotationMouseState.previousPosition = mousePosition;
-        _globalRotationMouseState.velocity.set(glm::dvec2(0, 0));
+        _globalRotationMouseState.velocity.set(glm::dvec2(0, 0), deltaTime);
     }
     if (button2Pressed) {
         glm::dvec2 mousePositionDelta =
             _truckMovementMouseState.previousPosition - mousePosition;
-        _truckMovementMouseState.velocity.set(mousePositionDelta * deltaTime * _sensitivity);
+        _truckMovementMouseState.velocity.set(mousePositionDelta * deltaTime * _sensitivity, deltaTime);
     }
     else { // !button2Pressed
         _truckMovementMouseState.previousPosition = mousePosition;
-        _truckMovementMouseState.velocity.set(glm::dvec2(0, 0));
+        _truckMovementMouseState.velocity.set(glm::dvec2(0, 0), deltaTime);
     }
     if (button3Pressed) {
         glm::dvec2 mousePositionDelta =
             _rollMouseState.previousPosition - mousePosition;
-        _rollMouseState.velocity.set(mousePositionDelta * deltaTime * _sensitivity);
+        _rollMouseState.velocity.set(mousePositionDelta * deltaTime * _sensitivity, deltaTime);
     }
     else { // !button3Pressed
         _rollMouseState.previousPosition = mousePosition;
-        _rollMouseState.velocity.set(glm::dvec2(0, 0));
+        _rollMouseState.velocity.set(glm::dvec2(0, 0), deltaTime);
     }
 }
 
@@ -1013,9 +1013,9 @@ InteractionHandler::InteractionHandler()
     // Create the interactionModes
     _inputState = std::shared_ptr<InputState>(new InputState());
     _orbitalInteractionMode = std::shared_ptr<OrbitalInteractionMode>(
-        new OrbitalInteractionMode(_inputState, 0.002, 0.02));
+        new OrbitalInteractionMode(_inputState, 0.002, 1));
     _globebrowsingInteractionMode = std::shared_ptr<GlobeBrowsingInteractionMode>(
-        new GlobeBrowsingInteractionMode(_inputState, 0.002, 0.02));
+        new GlobeBrowsingInteractionMode(_inputState, 0.002, 1));
 
     // Set the interactionMode
     _currentInteractionMode = _orbitalInteractionMode;