drafting along the RenderTHread class

interface/src/Application.cpp

@@ -2425,6 +2425,7 @@ void Application::cleanupBeforeQuit() {
     }
 
     _window->saveGeometry();
+
    // _gpuContext->shutdown();
 
     // Destroy third party processes after scripts have finished using them.
@@ -4178,41 +4179,37 @@ bool Application::acceptSnapshot(const QString& urlString) {
     }
     return true;
 }
-
-static uint32_t _renderedFrameIndex { INVALID_FRAME };
-
-bool Application::shouldPaint() const {
-    if (_aboutToQuit || _window->isMinimized()) {
-        return false;
-    }
-
-
-    auto displayPlugin = getActiveDisplayPlugin();
-
-#ifdef DEBUG_PAINT_DELAY
-    static uint64_t paintDelaySamples{ 0 };
-    static uint64_t paintDelayUsecs{ 0 };
-
-    paintDelayUsecs += displayPlugin->getPaintDelayUsecs();
-
-    static const int PAINT_DELAY_THROTTLE = 1000;
-    if (++paintDelaySamples % PAINT_DELAY_THROTTLE == 0) {
-        qCDebug(interfaceapp).nospace() <<
-            "Paint delay (" << paintDelaySamples << " samples): " <<
-            (float)paintDelaySamples / paintDelayUsecs << "us";
-    }
-#endif
-
-    // Throttle if requested
-    //if (displayPlugin->isThrottled() && (_graphicsEngine._renderEventHandler->_lastTimeRendered.elapsed() < THROTTLED_SIM_FRAME_PERIOD_MS)) {
-    if (displayPlugin->isThrottled() && !_graphicsEngine.shouldPaint()) {
-        return false;
-    }
-
-    // Sync up the _renderedFrameIndex
-    _renderedFrameIndex = displayPlugin->presentCount();
-    return true;
-}
+//
+//bool Application::shouldPaint() const {
+//    if (_aboutToQuit || _window->isMinimized()) {
+//        return false;
+//    }
+//
+//
+//    auto displayPlugin = getActiveDisplayPlugin();
+//
+//#ifdef DEBUG_PAINT_DELAY
+//    static uint64_t paintDelaySamples{ 0 };
+//    static uint64_t paintDelayUsecs{ 0 };
+//
+//    paintDelayUsecs += displayPlugin->getPaintDelayUsecs();
+//
+//    static const int PAINT_DELAY_THROTTLE = 1000;
+//    if (++paintDelaySamples % PAINT_DELAY_THROTTLE == 0) {
+//        qCDebug(interfaceapp).nospace() <<
+//            "Paint delay (" << paintDelaySamples << " samples): " <<
+//            (float)paintDelaySamples / paintDelayUsecs << "us";
+//    }
+//#endif
+//
+//    // Throttle if requested
+//    //if (displayPlugin->isThrottled() && (_graphicsEngine._renderEventHandler->_lastTimeRendered.elapsed() < THROTTLED_SIM_FRAME_PERIOD_MS)) {
+//    if (displayPlugin->isThrottled() && !_graphicsEngine.shouldPaint()) {
+//        return false;
+//    }
+//
+//    return true;
+//}
 
 #ifdef Q_OS_WIN
 #include <Windows.h>

interface/src/Application.h

@@ -157,7 +157,7 @@ public:
     void updateSecondaryCameraViewFrustum();
 
     void updateCamera(RenderArgs& renderArgs, float deltaTime);
-    bool shouldPaint() const;
+ //   bool shouldPaint() const;
 //    void paintGL();
     void resizeGL();
 

interface/src/graphics/GraphicsEngine.cpp

@@ -53,6 +53,7 @@ void GraphicsEngine::initializeGPU(GLWidget* glwidget) {
 
     _renderEventHandler = new RenderEventHandler(
         glwidget->qglContext(),
+        [this]() { return this->shouldPaint(); },
         [this]() { this->render_performFrame(); }
     );
 
@@ -147,12 +148,37 @@ static const int THROTTLED_SIM_FRAME_PERIOD_MS = MSECS_PER_SECOND / THROTTLED_SI
 
 
 bool GraphicsEngine::shouldPaint() const {
-    // Throttle if requested
-    if ((static_cast<RenderEventHandler*>(_renderEventHandler)->_lastTimeRendered.elapsed() < THROTTLED_SIM_FRAME_PERIOD_MS)) {
-        return false;
-    }
-    
-    return true;
+
+//        if (_aboutToQuit || _window->isMinimized()) {
+//            return false;
+ //       }
+
+
+        auto displayPlugin = qApp->getActiveDisplayPlugin();
+
+#ifdef DEBUG_PAINT_DELAY
+        static uint64_t paintDelaySamples{ 0 };
+        static uint64_t paintDelayUsecs{ 0 };
+
+        paintDelayUsecs += displayPlugin->getPaintDelayUsecs();
+
+        static const int PAINT_DELAY_THROTTLE = 1000;
+        if (++paintDelaySamples % PAINT_DELAY_THROTTLE == 0) {
+            qCDebug(interfaceapp).nospace() <<
+                "Paint delay (" << paintDelaySamples << " samples): " <<
+                (float)paintDelaySamples / paintDelayUsecs << "us";
+        }
+#endif
+
+        // Throttle if requested
+        //if (displayPlugin->isThrottled() && (_graphicsEngine._renderEventHandler->_lastTimeRendered.elapsed() < THROTTLED_SIM_FRAME_PERIOD_MS)) {
+        if (    displayPlugin->isThrottled() &&
+                (static_cast<RenderEventHandler*>(_renderEventHandler)->_lastTimeRendered.elapsed() < THROTTLED_SIM_FRAME_PERIOD_MS)) {
+            return false;
+        }
+
+        return true;
+  //  }
 }
 
 bool GraphicsEngine::checkPendingRenderEvent() {

interface/src/graphics/GraphicsEngine.h

@@ -16,6 +16,8 @@
 
 #include <render/Engine.h>
 
+#include "RenderThread.h"
+
 #include <OctreeConstants.h>
 #include <shared/RateCounter.h>
 
@@ -51,6 +53,8 @@ public:
     render::EnginePointer getRenderEngine() const { return _renderEngine; }
     gpu::ContextPointer getGPUContext() const { return _gpuContext; }
 
+    FrameQueuePointer getFrameQueue() const { return _frameQueue; }
+
     // Same as the one in application
     bool shouldPaint() const;
     bool checkPendingRenderEvent();
@@ -79,6 +83,8 @@ protected:
 
     gpu::ContextPointer _gpuContext; // initialized during window creation
 
+    FrameQueuePointer _frameQueue{ new FrameQueue() };
+
     QObject* _renderEventHandler{ nullptr };
     friend class RenderEventHandler;
 

interface/src/graphics/RenderEventHandler.cpp

@@ -15,7 +15,8 @@
 
 #include "CrashHandler.h"
 
-RenderEventHandler::RenderEventHandler(QOpenGLContext* context, RenderCall renderCall) :
+RenderEventHandler::RenderEventHandler(QOpenGLContext* context, CheckCall checkCall, RenderCall renderCall) :
+    _checkCall(checkCall),
     _renderCall(renderCall)
 {
     _renderContext = new OffscreenGLCanvas();
@@ -52,7 +53,7 @@ void RenderEventHandler::resumeThread() {
 }
 
 void RenderEventHandler::render() {
-    if (qApp->shouldPaint()) {
+    if (_checkCall()) {
         _lastTimeRendered.start();
         _renderCall();
     }

interface/src/graphics/RenderEventHandler.h

@@ -28,10 +28,13 @@ class RenderEventHandler : public QObject {
     Q_OBJECT
 public:
 
+    using CheckCall = std::function <bool()>;
     using RenderCall = std::function <void()>;
+
+    CheckCall _checkCall;
     RenderCall _renderCall;
 
-    RenderEventHandler(QOpenGLContext* context, RenderCall renderCall);
+    RenderEventHandler(QOpenGLContext* context, CheckCall checkCall, RenderCall renderCall);
 
     QElapsedTimer _lastTimeRendered;
     std::atomic<bool> _pendingRenderEvent{ true };

interface/src/graphics/RenderThread.cpp

@@ -0,0 +1 @@
+#include "RenderThread.h"

interface/src/graphics/RenderThread.h

@@ -0,0 +1,108 @@
+#ifndef PRODUCERCONSUMERPIPE_H
+#define PRODUCERCONSUMERPIPE_H
+
+#include <array>
+#include <atomic>
+#include <mutex>
+#include <condition_variable>
+#include <memory>
+
+// Producer is blocked if the consumer doesn't consume enough
+// Consumer reads same value if producer doesn't produce enough
+template <class T>
+class ProducerConsumerPipe {
+public:
+
+    ProducerConsumerPipe();
+    ProducerConsumerPipe(const T& initValue);
+
+    const T& read();
+    void read(T& value, const T& resetValue);
+    void write(const T& value);
+    bool isWritePossible();
+
+private:
+
+    short _readIndex;
+    short _writeIndex;
+    std::array<T, 3> _values;
+    std::array<std::atomic_flag, 3> _used;
+
+    void initialize();
+    void updateReadIndex();
+};
+
+template <class T>
+ProducerConsumerPipe<T>::ProducerConsumerPipe() {
+    initialize();
+}
+
+template <class T>
+ProducerConsumerPipe<T>::ProducerConsumerPipe(const T& initValue) {
+    _values.fill(initValue);
+    initialize();
+}
+
+template <class T>
+void ProducerConsumerPipe<T>::initialize() {
+    _readIndex = 0;
+    _writeIndex = 2;
+    _used[_readIndex].test_and_set(std::memory_order_acquire);
+    _used[_writeIndex].test_and_set(std::memory_order_acquire);
+    _used[1].clear();
+}
+
+template <class T>
+void ProducerConsumerPipe<T>::updateReadIndex() {
+    int nextReadIndex = (_readIndex + 1) % _values.size();
+
+    if (!_used[nextReadIndex].test_and_set(std::memory_order_acquire)) {
+        int readIndex = _readIndex;
+        _used[readIndex].clear(std::memory_order_release);
+        _readIndex = nextReadIndex;
+    }
+}
+
+template <class T>
+const T& ProducerConsumerPipe<T>::read() {
+    updateReadIndex();
+    return _values[_readIndex];
+}
+
+template <class T>
+void ProducerConsumerPipe<T>::read(T& value, const T& resetValue) {
+    updateReadIndex();
+    value = _values[_readIndex];
+    _values[_readIndex] = resetValue;
+}
+
+template <class T>
+bool ProducerConsumerPipe<T>::isWritePossible() {
+    int nextWriteIndex = (_writeIndex + 1) % _values.size();
+    return (_used[nextWriteIndex].test_and_set(std::memory_order_acquire));
+}
+
+template <class T>
+void ProducerConsumerPipe<T>::write(const T& value) {
+    int nextWriteIndex = (_writeIndex + 1) % _values.size();
+    int writeIndex = _writeIndex;
+
+    _values[writeIndex] = value;
+
+    while (_used[nextWriteIndex].test_and_set(std::memory_order_acquire)) {
+        // spin
+        std::this_thread::yield();
+    }
+    _used[writeIndex].clear(std::memory_order_release);
+    _writeIndex = nextWriteIndex;
+}
+
+
+#include <gpu/Frame.h>
+
+using FrameQueue = ProducerConsumerPipe<gpu::FramePointer>;
+
+using FrameQueuePointer = std::shared_ptr<FrameQueue>;
+
+
+#endif