Confirmed working implementation of Node UpdateCallback. For now example

used in visual effect on selecting a source as current.

Mixer.cpp

@@ -326,6 +326,8 @@ void Mixer::insertSource(Source *s, bool makecurrent)
 
             // set this new source as current
             setCurrentSource( sit );
+
+//            s->group(View::MIXING)->update_callbacks_.push_back(new MoveToCenterCallback);
         }
     }
 }
@@ -403,6 +405,9 @@ void Mixer::setCurrentSource(SourceList::iterator it)
 
         // show status as current
         (*current_source_)->setMode(Source::CURRENT);
+
+        (*current_source_)->group(View::MIXING)->update_callbacks_.push_back(new BounceScaleCallback);
+        (*current_source_)->group(View::LAYER)->update_callbacks_.push_back(new BounceScaleCallback);
     }
 
 }

Scene.cpp

@@ -57,10 +57,20 @@ void Node::copyTransform(Node *other)
 void Node::update( float dt)
 {
     std::list<UpdateCallback *>::iterator iter;
-    for (iter=update_callbacks_.begin(); iter != update_callbacks_.end(); iter++)
+    for (iter=update_callbacks_.begin(); iter != update_callbacks_.end(); )
     {
-        if ((*iter)->enabled())
-            (*iter)->update(this, dt);
+        UpdateCallback *callback = *iter;
+
+        if (callback->enabled())
+            callback->update(this, dt);
+
+        if (callback->finished()) {
+            iter = update_callbacks_.erase(iter);
+            delete callback;
+        }
+        else {
+            iter++;
+        }
     }
 
     // update transform matrix from attributes

UpdateCallback.cpp

@@ -1,16 +1,19 @@
 #include "UpdateCallback.h"
 
+#include "defines.h"
 #include "Scene.h"
+#include "Log.h"
 
 #include <glm/gtc/type_ptr.hpp>
 
-UpdateCallback::UpdateCallback() : enabled_(true)
+UpdateCallback::UpdateCallback() : enabled_(true), finished_(false)
 {
 
 }
 
 void MoveToCenterCallback::update(Node *n, float dt)
 {
+
     // set start position on first run or upon call of reset()
     if (!initialized_){
         initial_position_ = n->translation_;
@@ -18,13 +21,37 @@ void MoveToCenterCallback::update(Node *n, float dt)
     }
 
     // calculate amplitude of movement
-    float percent = dt / duration_;
+    progress_ += dt / duration_;
 
     // perform movement : translation to the center (0, 0)
-    n->translation_ = initial_position_ - percent * initial_position_;
+    n->translation_.x = initial_position_.x - progress_ * initial_position_.x;
+    n->translation_.y = initial_position_.y - progress_ * initial_position_.y;
 
-    // detect end of movement
-    if ( glm::distance(initial_position_, n->translation_) < 0.1f) {
-        disable();
+    // end of movement
+    if ( progress_ > 1.f ) {
+        n->translation_.x = 0.f;
+        n->translation_.y = 0.f;
+        finished_ = true;
+    }
+}
+
+void BounceScaleCallback::update(Node *n, float dt)
+{
+    // set start scale on first run or upon call of reset()
+    if (!initialized_){
+        initial_scale_ = n->scale_;
+        initialized_ = true;
+    }
+
+    // calculate amplitude of movement
+    progress_ += dt / duration_;
+
+    n->scale_.x = initial_scale_.x + (initial_scale_.x * 0.05f) * sin(M_PI * progress_);
+    n->scale_.y = initial_scale_.y + (initial_scale_.y * 0.05f) * sin(M_PI * progress_);
+
+    // end of movement
+    if ( progress_ > 1.f) {
+        n->scale_ = initial_scale_;
+        finished_ = true;
     }
 }

UpdateCallback.h

@@ -7,30 +7,46 @@ class Node;
 
 class UpdateCallback
 {
-    bool enabled_;
 
 public:
     UpdateCallback();
 
     virtual void update(Node *, float) = 0;
 
-    inline bool enabled() const {return enabled_;}
-    inline void enable() { enabled_ = true; }
-    inline void disable() { enabled_ = false; }
+    inline bool finished() const { return finished_; }
+    inline bool enabled() const { return enabled_; }
+
+protected:
+    bool enabled_;
+    bool finished_;
 };
 
 class MoveToCenterCallback : public UpdateCallback
 {
     float duration_;
+    float progress_;
     bool initialized_;
     glm::vec3 initial_position_;
 
 public:
-    MoveToCenterCallback(float duration = 1000.f) : duration_(duration), initialized_(false) {}
+    MoveToCenterCallback(float duration = 1000.f) : duration_(duration), progress_(0.f), initialized_(false) {}
 
     void update(Node *n, float dt);
 
     inline void reset() { initialized_ = false; }
 };
 
+class BounceScaleCallback : public UpdateCallback
+{
+    float duration_;
+    float progress_;
+    bool initialized_;
+    glm::vec3 initial_scale_;
+
+public:
+    BounceScaleCallback(float duration = 100.f) : duration_(duration), progress_(0.f), initialized_(false) {}
+
+    void update(Node *n, float dt);
+};
+
 #endif // UPDATECALLBACK_H