add scope widget

CMakeLists.txt

@@ -57,8 +57,8 @@ qt_add_executable(metabolus
     src/synth/Envelope.h
     src/synth/Synth.cpp
     src/synth/Synth.h
-    src/synth/SynthBuffer.cpp
-    src/synth/SynthBuffer.h
+    src/synth/ScopeBuffer.cpp
+    src/synth/ScopeBuffer.h
     resources/resources.qrc
     src/ui/widgets/SmartSlider/SmartSlider.cpp
     src/ui/widgets/SmartSlider/SmartSlider.h

src/synth/Envelope.h

@@ -22,10 +22,10 @@ public:
     // setters
     void setSampleRate(float sampleRate) { sampleRate_ = sampleRate; }
     void set(float a, float d, float s, float r) { setAttack(a); setDecay(d); setSustain(s); setRelease(r); }
-    void setAttack(float seconds) { attack_ = std::max(seconds, 0.0001f); }
-    void setDecay(float seconds) { decay_ = std::max(seconds, 0.0001f); }
+    void setAttack(float seconds) { attack_ = std::max(seconds, 0.001f); }
+    void setDecay(float seconds) { decay_ = std::max(seconds, 0.001f); }
     void setSustain(float level) { sustain_ = level; }
-    void setRelease(float seconds) { release_ = std::max(seconds, 0.0001f); }
+    void setRelease(float seconds) { release_ = std::max(seconds, 0.001f); }
     // values close to zero introduce that popping sound on noteOn/noteOffs
 
     // note events

src/synth/ScopeBuffer.cpp

@@ -0,0 +1,19 @@
+
+#include "ScopeBuffer.h"
+
+ScopeBuffer::ScopeBuffer(size_t size) : buffer_(size) {
+
+}
+
+void ScopeBuffer::push(float sample) {
+    size_t w = writeIndex_.fetch_add(1, std::memory_order_relaxed);
+    buffer_[w % buffer_.size()] = sample;
+}
+
+void ScopeBuffer::read(std::vector<float>& out) const {
+    size_t w = writeIndex_.load(std::memory_order_relaxed);
+    for (size_t i = 0; i < out.size(); i++) {
+        size_t idx = (w + trigger_ + i * wavelength_ / out.size()) % buffer_.size();
+        out[i] = buffer_[idx];
+    }
+}

src/synth/ScopeBuffer.h

@@ -0,0 +1,33 @@
+
+#pragma once
+
+#include <vector>
+#include <atomic>
+
+class ScopeBuffer {
+public:
+
+    explicit ScopeBuffer(size_t size);
+    ~ScopeBuffer() = default;
+
+    // add/read from the buffer
+    void push(float sample);
+    void read(std::vector<float>& out) const;
+
+    // setters/getters
+    void setTrigger(int32_t trigger) { trigger_ = trigger; }
+    void setWavelength(int32_t wavelength) { wavelength_ = wavelength; }
+    int32_t trigger() { return trigger_; }
+    int32_t wavelength() { return wavelength_; }
+
+    // NOTE: there are limits to the wavelengths that the scope can show cleanly due to the size of the audio buffer
+    // at a buffer size of 256 at 44100hz the min visible steady frequency is ~172hz
+private:
+
+    std::vector<float> buffer_;
+    std::atomic<size_t> writeIndex_{0};
+
+    int32_t trigger_ = 0; // units in array indices
+    int32_t wavelength_ = 400;
+
+};

src/synth/Synth.cpp

@@ -65,6 +65,7 @@ void Synth::process(float* out, uint32_t nFrames, uint32_t sampleRate) {
     updateParams();
 
     float sampleOut = 0.0f;
+    bool triggered = false;
 
     for (uint32_t i = 0; i < nFrames; i++) {
 
@@ -82,6 +83,7 @@ void Synth::process(float* out, uint32_t nFrames, uint32_t sampleRate) {
         if(!gainEnvelope_.isActive()) {
             out[2*i] = 0.0f;
             out[2*i+1] = 0.0f;
+            scope_->push(0.0f);
             continue;
         }
         
@@ -92,8 +94,8 @@ void Synth::process(float* out, uint32_t nFrames, uint32_t sampleRate) {
         // TODO: wavetables should be scaled by their RMS for equal loudness (prelim standard = 0.707)
         float sineSample = std::sin(phase_);
         float squareSample = (phase_ >= M_PI) ? 0.707f : -0.707f;
-        float sawSample = phase_ * 4.0f / M_PI * frequency_ / static_cast<float>(sampleRate); 
-        sampleOut = sawSample * gain;
+        float sawSample = ((phase_ / M_PI) - 1.0f) / 0.577f * 0.707f; 
+        sampleOut = squareSample * gain;
 
         // write to buffer
         out[2*i] = sampleOut; // left
@@ -102,12 +104,17 @@ void Synth::process(float* out, uint32_t nFrames, uint32_t sampleRate) {
         // write to scope buffer
         if (scope_) {
             scope_->push(sampleOut); // visualization tap
-            // set trigger info here too
         }
 
         // sampling business
         phase_ += phaseInc;
-        if (phase_ > 2.0f * M_PI) phase_ -= 2.0f * M_PI;
+        if (phase_ > 2.0f * M_PI) {
+            phase_ -= 2.0f * M_PI;
+            if(!triggered) {
+                scope_->setTrigger(i); // this is where we consider the start of a waveform
+                triggered = true;
+            }
+        }
     }
 
 }

src/ui/MainWindow.cpp

@@ -16,7 +16,7 @@ MainWindow::MainWindow(QWidget *parent) :
     setFocusPolicy(Qt::StrongFocus);
 
     // connect scope
-    ui_->scopeWidget->setScopeBuffer(&audioEngine_->scopeBuffer());
+    ui_->scope->setScopeBuffer(&audio_->scopeBuffer());
 
     // Connect buttons to slots
     connect(ui_->buttonReset, &QPushButton::clicked, this, &MainWindow::onResetClicked);

src/ui/MainWindow.ui

@@ -7,7 +7,7 @@
     <x>0</x>
     <y>0</y>
     <width>800</width>
-    <height>800</height>
+    <height>600</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -39,7 +39,7 @@
     <property name="geometry">
      <rect>
       <x>150</x>
-      <y>130</y>
+      <y>230</y>
       <width>500</width>
       <height>360</height>
      </rect>
@@ -55,7 +55,7 @@
     <property name="geometry">
      <rect>
       <x>200</x>
-      <y>540</y>
+      <y>20</y>
       <width>400</width>
       <height>200</height>
      </rect>

src/ui/widgets/Scope/Scope.cpp

@@ -0,0 +1,62 @@
+
+#include "Scope.h"
+#include "ui_Scope.h"
+
+#include "../../../synth/ScopeBuffer.h"
+
+#include <QPainter>
+#include <iostream>
+
+Scope::Scope(QWidget* parent) : QWidget(parent), ui_(new Ui::Scope), samples_(512) {
+    
+    timer_.setInterval(16); // ~60 hz
+    connect(&timer_, &QTimer::timeout, this, QOverload<>::of(&Scope::update));
+    timer_.start();
+}
+
+Scope::~Scope() {
+    delete ui_;
+}
+
+void Scope::setScopeBuffer(ScopeBuffer* buffer) {
+    buffer_ = buffer;
+}
+
+void Scope::paintEvent(QPaintEvent*) {
+    if (!buffer_) return;
+
+    int32_t wavelength = buffer_->wavelength();
+    int32_t trigger = buffer_->trigger();
+
+    buffer_->read(samples_);
+    
+    // auto scale amplitude. disabled because it hides the envelope effects
+    float maxAmp = 1.0f;
+    //for (float s : samples_) {
+    //    maxAmp = std::max(maxAmp, std::abs(s));
+    //}
+    // TODO: if you get really bored you can start adding scope display options
+        
+    float scaleY = (height() * 0.45f) / maxAmp;
+    float midY = height() / 2.0f;
+
+    QPainter p(this);
+    QColor gray(20, 20, 20);
+    p.fillRect(rect(), gray);
+
+    // got caught playing around
+    QPen pen;
+    pen.setWidthF(2.0f);
+    QColor green(50, 255, 70);
+    pen.setColor(green);
+    p.setPen(pen);
+
+    for (int32_t i = 1; i < samples_.size(); i++) {
+        p.drawLine(
+            (i - 1) * width() / samples_.size(),
+            midY - samples_[i - 1] * scaleY,
+            i * width() / samples_.size(),
+            midY - samples_[i] * scaleY
+        );
+    }
+}

src/ui/widgets/Scope/Scope.h

@@ -0,0 +1,35 @@
+
+#pragma once
+
+#include <QWidget>
+#include <QTimer>
+#include <vector>
+
+// forward declaration
+class ScopeBuffer;
+
+QT_BEGIN_NAMESPACE
+namespace Ui { class Scope; }
+QT_END_NAMESPACE
+
+class Scope : public QWidget {
+    Q_OBJECT
+public:
+    explicit Scope(QWidget* parent = nullptr);
+    ~Scope();
+
+    void setScopeBuffer(ScopeBuffer* buffer);
+
+protected:
+    // autocalled on QT's refresh loop
+    // scope drawing happens here
+    void paintEvent(QPaintEvent*) override;
+
+private:
+
+    Ui::Scope* ui_;
+
+    ScopeBuffer* buffer_ = nullptr;
+    std::vector<float> samples_;
+    QTimer timer_;
+};

src/ui/widgets/Scope/Scope.ui

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>Scope</class>
+ <widget class="QWidget" name="Scope">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>400</width>
+    <height>200</height>
+   </rect>
+  </property>
+  <property name="sizePolicy">
+   <sizepolicy hsizetype="Preferred" vsizetype="Preferred">
+    <horstretch>0</horstretch>
+    <verstretch>0</verstretch>
+   </sizepolicy>
+  </property>
+  <property name="windowTitle">
+   <string>Form</string>
+  </property>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>