Implementation of user defined mixing deactivation limit

Mixing view handles to grab and scale limbo area. Saving of user defined limit in Session (and snapshot). Testing for source activation outside of update during session update loop.

Source.cpp

@@ -519,6 +519,10 @@ void Source::attach(FrameBuffer *renderbuffer)
 
 void Source::setActive (bool on)
 {
+    // request update
+    need_update_ |= active_ != on;
+
+    // activate
     active_ = on;
 
     // do not disactivate if a clone depends on it
@@ -571,6 +575,11 @@ void Source::setDepth(float d)
     touch();
 }
 
+float Source::mix_distance()
+{
+    return glm::length( glm::vec2(groups_[View::MIXING]->translation_) );
+}
+
 float Source::alpha() const
 {
     return blendingShader()->color.a;
@@ -578,6 +587,7 @@ float Source::alpha() const
 
 void Source::setAlpha(float a)
 {
+    a = CLAMP(a, 0.f, 1.f);
     glm::vec2 dist = glm::vec2(groups_[View::MIXING]->translation_);
     glm::vec2 step = glm::normalize(glm::vec2(1.f, 1.f));// step in diagonal by default
 
@@ -587,10 +597,10 @@ void Source::setAlpha(float a)
 
     // converge to reduce the difference of alpha
     // using dichotomic algorithm
-    float delta = sin_quad_(dist.x, dist.y) - CLAMP(a, 0.f, 1.f);
+    float delta = sin_quad_(dist.x, dist.y) - a;
     while ( glm::abs(delta) > DELTA_ALPHA ){
         dist += step * (delta / 2.f);
-        delta = sin_quad_(dist.x, dist.y) - CLAMP(a, 0.f, 1.f);
+        delta = sin_quad_(dist.x, dist.y) - a;
     }
 
     // apply new mixing coordinates
@@ -613,12 +623,8 @@ void Source::update(float dt)
         // use the sinusoidal transfer function
         blendingshader_->color = glm::vec4(1.f, 1.f, 1.f, sin_quad_( dist.x, dist.y ));
         mixingshader_->color = blendingshader_->color;
-
-        // CHANGE update status based on limbo
-        bool a = glm::length(dist) < MIXING_LIMBO_SCALE;
-        setActive( a );
         // adjust scale of mixing icon : smaller if not active
-        groups_[View::MIXING]->scale_ = glm::vec3(MIXING_ICON_SCALE) - ( a ? glm::vec3(0.f, 0.f, 0.f) : glm::vec3(0.03f, 0.03f, 0.f) );
+        groups_[View::MIXING]->scale_ = glm::vec3(MIXING_ICON_SCALE) - ( active_ ? glm::vec3(0.f, 0.f, 0.f) : glm::vec3(0.03f, 0.03f, 0.f) );
 
         // MODIFY geometry based on GEOMETRY node
         groups_[View::RENDERING]->translation_ = groups_[View::GEOMETRY]->translation_;