linux + piano keyboard support

src/synth/Instruments/PianoString.cpp

@@ -37,7 +37,7 @@ void PianoString::noteOn(float frequency, float velocity) {
     }
     // apply the velocity impulse
     for(size_t i = 0; i < segmentCount_ + 1; i++) {
-        float v0 = impulseVelocity_ * std::exp(-1.0f * (stringX_[i] - strikePosition_*L_)*(stringX_[i] - strikePosition_*L_) / ((2.0f * impulseWidth_)*(2.0f * impulseWidth_)));
+        float v0 = velocity * impulseVelocity_ * std::exp(-1.0f * (stringX_[i] - strikePosition_*L_)*(stringX_[i] - strikePosition_*L_) / ((2.0f * impulseWidth_)*(2.0f * impulseWidth_)));
         stringY_current_[i] = stringY_current_[i] + dt_ * v0;
     }
 

src/synth/Instruments/PianoString.hpp

@@ -50,7 +50,7 @@ private:
     float mu_ = crossSectionalArea_ * rho_; // linear mass density
     float waveVelocity_ = std::sqrt(stringTension_ / mu_); // transverse wave velocity
     float L_ = 1.0f; // length of string at a given frequency
-    float gain_ = 0.3f;
+    float gain_ = 0.5f;
 
     // f0_ = waveVelocity_ / (2.0f * stringLength_); // fundamental frequency of a non-stiff string
     // f1_ = f0_ * std::sqrt(1.0f + stiffness_); // fundamental frequency of the stiff string