Small fixing to metronome example, works again

Signed-off-by: falkTX <falktx@falktx.com>

examples/Metronome/ExamplePluginMetronome.cpp

@@ -46,13 +46,15 @@ public:
       - Single-pole IIR low-pass filter - which is the correct formula for the decay coefficient?
         https://dsp.stackexchange.com/questions/54086/single-pole-iir-low-pass-filter-which-is-the-correct-formula-for-the-decay-coe
      */
-    void setCutoff(float sampleRate, float cutoffHz) {
+    void setCutoff(const float sampleRate, const float cutoffHz)
+    {
         double omega_c = 2.0 * M_PI * cutoffHz / sampleRate;
         double y = 1.0 - std::cos(omega_c);
         kp = float(-y + std::sqrt((y + 2.0) * y));
     }
 
-    float process(float input) {
+    inline float process(const float input)
+    {
         return value += kp * (input - value);
     }
 };
@@ -77,6 +79,7 @@ public:
           cent(0),
           decayTime(0.2f)
     {
+        sampleRateChanged(sampleRate);
     }
 
 protected:
@@ -158,7 +161,7 @@ protected:
         case 0:
             parameter.name = "Gain";
             parameter.hints |= kParameterIsLogarithmic;
-            parameter.ranges.min = 0.0f;
+            parameter.ranges.min = 0.001f;
             parameter.ranges.max = 1.0f;
             parameter.ranges.def = 0.5f;
             break;
@@ -236,6 +239,17 @@ protected:
    /* --------------------------------------------------------------------------------------------------------
     * Process */
 
+   /**
+      Activate this plugin.
+      We use this to reset our filter states.
+    */
+   void activate() override
+   {
+        deltaPhaseSmoother.value = 0.0f;
+        envelopeSmoother.value = 0.0f;
+        gainSmoother.value = gain;
+   }
+
    /**
       Run/process function for plugins without MIDI input.
       `inputs` is commented out because this plugin has no inputs.
@@ -274,8 +288,8 @@ protected:
                 phase = 0.0f;
 
                 deltaPhaseSmoother.value = deltaPhase;
-                gainSmoother.value = 1.0f;
                 envelopeSmoother.value = 0.0f;
+                gainSmoother.value = 0.0f;
             }
 
             for (uint32_t i = 0; i < frames; ++i)
@@ -336,8 +350,8 @@ private:
     float decay;      // Coefficient to decay envelope in a frame.
 
     Smoother deltaPhaseSmoother;
-    Smoother gainSmoother;
     Smoother envelopeSmoother;
+    Smoother gainSmoother;
 
     // Parameters.
     float gain;

examples/Metronome/README.md

@@ -2,7 +2,7 @@
 
 This example will show tempo sync in DPF.<br/>
 
-This plugin will output sine wave at the start of every beat.<br/>
+This plugin will output a sine wave at the start of every beat.<br/>
 The pitch of sine wave is 1 octave higher at the start of every bar.<br/>
 
 4 parameters are avaialble:
@@ -17,15 +17,15 @@ To calculate frames to the next beat from the start of current audio buffer, fol
 ```c++
 const TimePosition& timePos(getTimePosition());
 
-if (timePos.bbt.valid) {
+if (timePos.bbt.valid)
+{
     double secondsPerBeat = 60.0 / timePos.bbt.beatsPerMinute;
     double framesPerBeat  = sampleRate * secondsPerBeat;
     double beatFraction   = timePos.bbt.tick / timePos.bbt.ticksPerBeat;
 
-    uint32_t framesToNextBeat = beatFraction == 0.0
-        ? 0
-        : static_cast<uint32_t>(framesPerBeat * (1.0 - beatFraction));
-
+    uint32_t framesToNextBeat = d_isZero(beatFraction)
+                              ? 0
+                              : static_cast<uint32_t>(framesPerBeat * (1.0 - beatFraction));
     // ...
 }
 ```