osciwidget.cpp

@@ -17,11 +17,11 @@ qint32 framesForDuration(qint64 duration){
 OsciWidget::OsciWidget(QWidget *parent)
     : QOpenGLWidget{parent}
     , m_bufferOffset{m_buffer.begin()}
-    , m_lastTime{0}
+    , m_lastBufferUpdate{0}
     , m_redrawTimerId(startTimer(1000/m_fps, Qt::PreciseTimer))
 {
     m_statsTimer.start();
-    m_bufferTimer.start();
+    m_globalTimer.start();
 }
 
 int OsciWidget::lightspeed() const
@@ -62,17 +62,18 @@ void OsciWidget::renderSamples(const SamplePair *begin, const SamplePair *end)
 
     auto offset = std::distance(m_buffer.begin(), m_bufferOffset);
 
-    if(m_bufferTimer.elapsed()-m_lastTime > 5000)
+    if(m_globalTimer.elapsed()-m_lastBufferUpdate > 5000)
     {
         //qDebug() << "deleting: " << m_bufferOffset - m_buffer.begin() << m_buffer.size();
         // Delete drawn frames
         //m_buffer.erase(m_buffer.begin(), m_bufferOffset);
 
         // TODO improve by drawing remaining(undrawn) buffer instead
+        drawBuffer(m_bufferOffset, m_buffer.end(), QColor(0, 255, 0));
         m_buffer.clear();
         offset = 0;
 
-        m_lastTime = m_bufferTimer.elapsed();
+        m_lastBufferUpdate = m_globalTimer.elapsed();
     }
     //qDebug () << " inserting " << std::distance(begin, end);
     m_buffer.insert(m_buffer.end(), begin, end);
@@ -88,7 +89,7 @@ void OsciWidget::paintEvent(QPaintEvent *event)
     m_frameCounter++;
     if (m_statsTimer.hasExpired(1000))
     {
-        emit statusUpdate(QString("%0FPS (%1 callbacks, %2 samples, %3 avg per callback, bufferSize %4, elapsed %5)").arg(m_frameCounter).arg(m_callbacksCounter).arg(m_samplesCounter).arg(m_callbacksCounter>0?m_samplesCounter/m_callbacksCounter:0).arg(m_buffer.size()).arg(m_bufferTimer.elapsed()));
+        emit statusUpdate(QString("%0FPS (%1 callbacks, %2 samples, %3 avg per callback, bufferSize %4, elapsed %5)").arg(m_frameCounter).arg(m_callbacksCounter).arg(m_samplesCounter).arg(m_callbacksCounter>0?m_samplesCounter/m_callbacksCounter:0).arg(m_buffer.size()).arg(m_globalTimer.elapsed()));
         m_frameCounter = 0;
         m_callbacksCounter = 0;
         m_samplesCounter = 0;
@@ -103,28 +104,32 @@ void OsciWidget::darkenFrame()
 {
     QPainter painter(&m_pixmap);
 
-    painter.setCompositionMode(QPainter::CompositionMode_Multiply);
-    painter.setPen({});
+
     //auto afterglowColor = 255 * pow(m_decayTime, 1.0/m_fps);
-    auto afterglowColor = static_cast<int>(255 * pow(exp(-1), 1000.0/m_decayTime/m_fps));
-    qDebug() << afterglowColor;
+    auto afterglowFactor = pow(exp(-1), 1000.0/m_decayTime/m_fps);
+    auto afterglowColor = static_cast<int>(255*afterglowFactor);
+    //qDebug() << afterglowFactor;
+    //QColor blendColor;
+    //black.setAlpha(afterglowColor);
+    painter.setCompositionMode(QPainter::CompositionMode_Multiply);
     painter.setBrush(QColor(afterglowColor, afterglowColor, afterglowColor));
     painter.drawRect(m_pixmap.rect());
     //m_pixmap.fill(Qt::black);
 }
 
 
-void OsciWidget::drawBuffer(SampleBuffer::iterator &bufferPos, const SampleBuffer::iterator &end)
+void OsciWidget::drawBuffer(SampleBuffer::iterator &bufferPos, const SampleBuffer::iterator &end, QColor color)
 {
     QPainter painter(&m_pixmap);
+    painter.setRenderHint(QPainter::Antialiasing);
     painter.translate(m_pixmap.width()/2, m_pixmap.height()/2);
     painter.scale(m_factor * m_pixmap.width() / 2.0, m_factor * m_pixmap.height() / 2.0);
 
     QPen pen;
     pen.setCosmetic(true); // let pen be scale invariant
     pen.setWidth(2);
-    pen.setColor(QColor(0, 255, 0));
-    painter.setPen(pen);
+    // This prevents most of the overlapping when drawing lines from and to the same points
+    pen.setCapStyle(Qt::FlatCap);
 
     for (;bufferPos < end; ++bufferPos)
     {
@@ -137,14 +142,26 @@ void OsciWidget::drawBuffer(SampleBuffer::iterator &bufferPos, const SampleBuffe
 
         const QLineF line(m_lastPoint, p);
 
-        auto beamOpacity = std::min(1.0, 1. / ((line.length() * m_lightspeed) + 1));
-
+        auto beamBrightness = std::min(1.0, 1. / ((line.length() * m_lightspeed) + 1));
 
+        // time from bufferPos to end in ms
         double time = 1000.0 * std::distance(bufferPos, end) / 44100.0;
-        auto beamDecay = exp(-time/m_decayTime);
 
-        painter.setOpacity(beamDecay*beamOpacity);
+        auto beamDecay = exp(-time/m_decayTime);
+        // HACK: gamma rolloff the brightness to make it look better (make configurable?)
+        auto beamVisibility = pow(beamBrightness, 2.0)*beamDecay;
+
+        QColor drawColor(color);
+        drawColor.setAlphaF(beamVisibility);
+        //QColor drawColor(color.red()*beamVisibility, color.green()*beamVisibility, color.blue()*beamVisibility);
+
+        pen.setColor(drawColor);
+        painter.setPen(pen);
+        //painter.setOpacity(beamVisibility);
         painter.drawLine(m_lastPoint, p);
+        //painter.drawLine(m_lastPoint, m_lastPoint);
+        //painter.setPen(pen);
+        //painter.drawPoint(m_lastPoint);
 
         m_lastPoint = p;
     }
@@ -166,14 +183,14 @@ void OsciWidget::updateDrawBuffer()
 
     resizeDrawBuffer();
     darkenFrame();
-    // persistance time is the time it needs to decay to 1/e ~ 36,7%
+    // decay time is the time it needs to decay to 1/e ~ 36,7%
 
-    auto duration = 1000*(m_bufferTimer.elapsed()-m_lastTime);
+    auto duration = 1000*(m_globalTimer.elapsed()-m_lastBufferUpdate);
     size_t framesOffset = framesForDuration(duration);
     //qDebug() << framesOffset << m_buffer.size()-framesOffset << m_bufferOffset - m_buffer.begin();
 
     auto bufferEnd = m_buffer.begin() + std::min(framesOffset, m_buffer.size());
-    drawBuffer(m_bufferOffset, bufferEnd);
+    drawBuffer(m_bufferOffset, bufferEnd, QColor(0, 255, 0));
 }
 
 void OsciWidget::timerEvent(QTimerEvent *event)

osciwidget.h

@@ -54,13 +54,13 @@ private:
 
     int m_frameCounter{0}, m_callbacksCounter{0}, m_samplesCounter{0};
     QElapsedTimer m_statsTimer;
-    QElapsedTimer m_bufferTimer;
-    qint64 m_lastTime;
+    QElapsedTimer m_globalTimer;
+    qint64 m_lastBufferUpdate;
 
     int m_redrawTimerId;
     QPointF m_lastPoint;
     QPixmap m_pixmap;
     void darkenFrame();
-    void drawBuffer(SampleBuffer::iterator &bufferPos, const SampleBuffer::iterator &end);
+    void drawBuffer(SampleBuffer::iterator &bufferPos, const SampleBuffer::iterator &end, QColor color);
     void resizeDrawBuffer();
 };