maybe fixed for windows

src/GLWidget.cpp

@@ -46,6 +46,7 @@ void GLWidget::initializeGL() {
 	simulation->semaphore.acquire();
 	uploadStaticDataToGPU();
 
+	makeCurrent();
 	overlay->init();
 }
 
@@ -102,6 +103,8 @@ bool GLWidget::AnyDialogOpen() {
 }
 
 void GLWidget::uploadStaticDataToGPU() {
+	makeCurrent();
+
 	auto pendula = &simulation->pendula;
 
 	size_t pointCount = std::transform_reduce(pendula->begin(), pendula->end(), 0, [](size_t prev, size_t curr){
@@ -183,10 +186,14 @@ void GLWidget::uploadStaticDataToGPU() {
 
 	glBindVertexArray(0);
 
+	doneCurrent();
+
 	simulation->semaphore.release();
 }
 
 void GLWidget::changePosition() {
+	makeCurrent();
+
 	auto t1 = system_clock::now();
 	glBindBuffer(GL_ARRAY_BUFFER, positionVBO);
 	auto positions = (GLfloat*) glMapBufferRange(GL_ARRAY_BUFFER, 0, GLsizeiptr(positionCount * sizeof(float)), GL_MAP_WRITE_BIT);
@@ -201,6 +208,8 @@ void GLWidget::changePosition() {
 	}
 	glUnmapBuffer(GL_ARRAY_BUFFER);
 	// std::cout << duration_cast<microseconds>(system_clock::now() - t1).count() << std::endl;
+
+	doneCurrent();
 	simulation->semaphore.release();
 }
 

src/GLWidget.h

@@ -1,7 +1,7 @@
 #pragma once
 
 #include <QOpenGLWidget>
-#include <QOpenGLExtraFunctions>
+#include <QOpenGLFunctions_3_3_Core>
 #include <QMatrix3x3>
 
 class Pendulum;
@@ -9,7 +9,7 @@ class Simulation;
 class QOpenGLShaderProgram;
 class Overlay;
 
-class GLWidget : public QOpenGLWidget, protected QOpenGLExtraFunctions {
+class GLWidget : public QOpenGLWidget, protected QOpenGLFunctions_3_3_Core {
 public:
 	explicit GLWidget(Simulation *);
 	Overlay * overlay;

src/MainWindow.cpp

@@ -18,13 +18,14 @@
 #include <QTimer>
 #include "Overlay.h"
 #include "Slider.h"
+#include <QOffscreenSurface>
 
 MainWindow::MainWindow() {
 	simulationThread = new QThread(this);
 	simulationThread->setObjectName("Simulation");
 	simulation = new Simulation;
 	simulation->moveToThread(simulationThread);
-	simulationThread->start();
+	connect(simulationThread, &QThread::started, simulation, &Simulation::initialize);
 
 	masses = std::vector<double>(MaxSegments);
 	lengths = std::vector<double>(MaxSegments);
@@ -36,7 +37,9 @@ MainWindow::MainWindow() {
 
 	normalizeLengths();
 
-	QMetaObject::invokeMethod(simulation, &Simulation::initialize);
+	auto offSurface = new QOffscreenSurface;
+	offSurface->create();
+	simulation->offSurface = offSurface;
 }
 
 void MainWindow::buildUI() {
@@ -383,13 +386,13 @@ QWidget * MainWindow::buildSimulationUI() {
 	// GPU-Acceleration
 	{
 		auto useGPU = new QCheckBox("Use GPU-Acceleration");
+        useGPU->setCheckState(Qt::Checked);
 		connect(useGPU, &QCheckBox::stateChanged, simulation, &Simulation::useGPUChanged);
 		connect(simulation, &Simulation::gpuNotSupported, [useGPU](const std::string &message){
 			useGPU->setCheckState(Qt::Unchecked);
 			useGPU->setEnabled(false);
 			useGPU->setToolTip(QString::fromStdString(message));
 		});
-		useGPU->setCheckState(Qt::Unchecked);
 
 		lyt->addWidget(useGPU);
 	}

src/MainWindow.h

@@ -15,12 +15,12 @@ class MainWindow : public QWidget {
 public:
 	explicit MainWindow();
 	~MainWindow() override;
+	QThread * simulationThread;
 private:
 	void buildUI();
 	QWidget * buildAddUI();
 	QWidget * buildSimulationUI();
 	Simulation * simulation;
-	QThread * simulationThread;
 
 	GLWidget * glWidget = nullptr;
 

src/Simulation.cpp

@@ -23,15 +23,19 @@ void Simulation::initialize() {
 
 	// OpenGL Offscreen functions
 	{
-		auto context = new QOpenGLContext(this);
-		context->setFormat(QSurfaceFormat::defaultFormat());
+		context = new QOpenGLContext;
+		auto format = QSurfaceFormat::defaultFormat();
+		format.setVersion(4, 3);
+		context->setFormat(format);
 		context->create();
-		auto surface = new QOffscreenSurface(nullptr, this);
-		surface->setFormat(context->format());
-		surface->create();
-		context->makeCurrent(surface);
-		initializeOpenGLFunctions();
-		if (!context->hasExtension("GL_ARB_gpu_shader_fp64")){
+		context->makeCurrent(offSurface);
+		f = new QOpenGLFunctions_4_3_Core;
+        if (!f->initializeOpenGLFunctions()){
+            std::string message = "OpenGL 4.3 is required for Compute Shaders! Falling back to CPU-Multithreading.";
+            printf("%s\n", message.c_str());
+            useGPUAcceleration = false;
+            emit gpuNotSupported(message);
+        } else if (!context->hasExtension("GL_ARB_gpu_shader_fp64")){
 			std::string message = "Double precision not supported by OpenGL! Falling back to CPU-Multithreading.";
 			printf("%s\n", message.c_str());
 			useGPUAcceleration = false;
@@ -39,13 +43,19 @@ void Simulation::initialize() {
 		}
 	}
 
+    if (!useGPUAcceleration){
+		context->doneCurrent();
+		return;
+	}
+
+
 	// Read GPU Limits
 	{
 		for (int i = 0; i < 3; i++){
-			glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_COUNT, i, gpuLimits.maxWGCount + i);
-			glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_SIZE, i, gpuLimits.maxWGSize + i);
+			f->glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_COUNT, i, gpuLimits.maxWGCount + i);
+			f->glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_SIZE, i, gpuLimits.maxWGSize + i);
 		}
-		glGetIntegerv(GL_MAX_COMPUTE_WORK_GROUP_INVOCATIONS, &gpuLimits.maxWGInvocations);
+		f->glGetIntegerv(GL_MAX_COMPUTE_WORK_GROUP_INVOCATIONS, &gpuLimits.maxWGInvocations);
 
 		printf("Max work group count: (%d, %d, %d)\n", gpuLimits.maxWGCount[0], gpuLimits.maxWGCount[1], gpuLimits.maxWGCount[2]);
 		printf("Max work group size: (%d, %d, %d)\n", gpuLimits.maxWGSize[0], gpuLimits.maxWGSize[1], gpuLimits.maxWGSize[2]);
@@ -58,19 +68,22 @@ void Simulation::initialize() {
 		program->addShaderFromSourceFile(QOpenGLShader::Compute, ":/shaders/compute.glsl");
 		program->link();
 
-		glGenBuffers(6, &SSBO.positions);
-		glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, SSBO.positions);
-		glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, SSBO.velocities);
-		glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 2, SSBO.invMasses);
-		glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3, SSBO.lengths);
-		glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 4, SSBO.indices);
-		glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 5, SSBO.segmentCounts);
+		f->glGenBuffers(6, &SSBO.positions);
+		f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, SSBO.positions);
+        f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, SSBO.velocities);
+        f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 2, SSBO.invMasses);
+        f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3, SSBO.lengths);
+        f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 4, SSBO.indices);
+        f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 5, SSBO.segmentCounts);
 	}
 
+	context->doneCurrent();
 }
 
 // When the layout changes
 void Simulation::updateGPUData() {
+	context->makeCurrent(offSurface);
+
 	std::vector<GLdouble> positions;
 	std::vector<GLdouble> velocities;
 	std::vector<GLdouble> invMasses;
@@ -100,18 +113,20 @@ void Simulation::updateGPUData() {
 	auto indicesSize = GLsizeiptr(indices.size() * sizeof(GLuint));
 	auto segmentCountsSize = GLsizeiptr(segmentCounts.size() * sizeof(GLuint));
 
-	glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.positions);
-	glBufferData(GL_SHADER_STORAGE_BUFFER, posSize, positions.data(), GL_DYNAMIC_DRAW);
-	glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.velocities);
-	glBufferData(GL_SHADER_STORAGE_BUFFER, velSize, velocities.data(), GL_DYNAMIC_DRAW);
-	glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.invMasses);
-	glBufferData(GL_SHADER_STORAGE_BUFFER, invMassSize, invMasses.data(), GL_STATIC_DRAW);
-	glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.lengths);
-	glBufferData(GL_SHADER_STORAGE_BUFFER, lengthSize, lengths.data(), GL_STATIC_DRAW);
-	glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.indices);
-	glBufferData(GL_SHADER_STORAGE_BUFFER, indicesSize, indices.data(), GL_STATIC_DRAW);
-	glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.segmentCounts);
-	glBufferData(GL_SHADER_STORAGE_BUFFER, segmentCountsSize, segmentCounts.data(), GL_STATIC_DRAW);
+    f->glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.positions);
+    f->glBufferData(GL_SHADER_STORAGE_BUFFER, posSize, positions.data(), GL_DYNAMIC_DRAW);
+    f->glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.velocities);
+    f->glBufferData(GL_SHADER_STORAGE_BUFFER, velSize, velocities.data(), GL_DYNAMIC_DRAW);
+    f->glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.invMasses);
+    f->glBufferData(GL_SHADER_STORAGE_BUFFER, invMassSize, invMasses.data(), GL_STATIC_DRAW);
+    f->glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.lengths);
+    f->glBufferData(GL_SHADER_STORAGE_BUFFER, lengthSize, lengths.data(), GL_STATIC_DRAW);
+    f->glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.indices);
+    f->glBufferData(GL_SHADER_STORAGE_BUFFER, indicesSize, indices.data(), GL_STATIC_DRAW);
+    f->glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.segmentCounts);
+    f->glBufferData(GL_SHADER_STORAGE_BUFFER, segmentCountsSize, segmentCounts.data(), GL_STATIC_DRAW);
+
+	context->doneCurrent();
 }
 
 // Every few milliseconds
@@ -129,18 +144,19 @@ void Simulation::update() {
 	double newKineticEnergy = 0;
 
 	if (useGPUAcceleration) {
+		context->makeCurrent(offSurface);
 		program->bind();
-		glUniform1d(program->uniformLocation("h"), h);
-		glUniform1d(program->uniformLocation("gravity"), gravity);
-		glUniform1ui(program->uniformLocation("substeps"), substeps);
+        f->glUniform1d(program->uniformLocation("h"), h);
+        f->glUniform1d(program->uniformLocation("gravity"), gravity);
+        f->glUniform1ui(program->uniformLocation("substeps"), substeps);
 
-		glDispatchCompute(pendula.size(), 1, 1);
-		glMemoryBarrier(GL_SHADER_STORAGE_BARRIER_BIT);
+        f->glDispatchCompute(pendula.size(), 1, 1);
+        f->glMemoryBarrier(GL_SHADER_STORAGE_BARRIER_BIT);
 
 		// Read updated positions
 		{
-			glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.positions);
-			auto * newPositions = (double*) glMapBuffer(GL_SHADER_STORAGE_BUFFER, GL_READ_ONLY);
+            f->glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.positions);
+			auto * newPositions = (double*) f->glMapBuffer(GL_SHADER_STORAGE_BUFFER, GL_READ_ONLY);
 			int index = 0;
 			for (Pendulum * p : pendula){
 				for (Vector &point : p->X){
@@ -148,13 +164,13 @@ void Simulation::update() {
 					point.y = newPositions[index++];
 				}
 			}
-			glUnmapBuffer(GL_SHADER_STORAGE_BUFFER);
+            f->glUnmapBuffer(GL_SHADER_STORAGE_BUFFER);
 		}
 
 		// Read updated velocities
 		{
-			glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.velocities);
-			auto * newVelocities = (double*) glMapBuffer(GL_SHADER_STORAGE_BUFFER, GL_READ_ONLY);
+            f->glBindBuffer(GL_SHADER_STORAGE_BUFFER, SSBO.velocities);
+			auto * newVelocities = (double*) f->glMapBuffer(GL_SHADER_STORAGE_BUFFER, GL_READ_ONLY);
 			int index = 0;
 			for (Pendulum * p : pendula){
 				for (Vector &velocity : p->V){
@@ -162,7 +178,7 @@ void Simulation::update() {
 					velocity.y = newVelocities[index++];
 				}
 			}
-			glUnmapBuffer(GL_SHADER_STORAGE_BUFFER);
+            f->glUnmapBuffer(GL_SHADER_STORAGE_BUFFER);
 		}
 
 		#pragma omp parallel for
@@ -174,7 +190,7 @@ void Simulation::update() {
 			#pragma omp atomic
 			newKineticEnergy += localKineticEnergy;
 		}
-
+		context->doneCurrent();
 	} else {
 		// CPU-Multithreading
 		#pragma omp parallel for
@@ -208,7 +224,8 @@ void Simulation::clearPendula() {
 	pendula.shrink_to_fit();
 
 	updateEnergy();
-	updateGPUData();
+    if (useGPUAcceleration)
+        updateGPUData();
 
 	emit layoutChanged();
 }
@@ -220,7 +237,8 @@ void Simulation::addPendula(const std::vector<Pendulum *> &add) {
 		pendula.push_back(p);
 
 	updateEnergy();
-	updateGPUData();
+    if (useGPUAcceleration)
+        updateGPUData();
 
 	emit layoutChanged();
 }

src/Simulation.h

@@ -5,11 +5,13 @@
 #include <semaphore>
 #include <QOpenGLFunctions_4_3_Core>
 
+class QOffscreenSurface;
+class QTimer;
 class FPS;
 class Pendulum;
 class QOpenGLShaderProgram;
 
-class Simulation : public QObject, protected QOpenGLFunctions_4_3_Core {
+class Simulation : public QObject {
 	Q_OBJECT
 public:
 	explicit Simulation();
@@ -29,19 +31,23 @@ public:
 	std::binary_semaphore semaphore = std::binary_semaphore(1);
 	FPS * ups;
 
-	void initialize();
+	QOffscreenSurface* offSurface;
+	QOpenGLContext* context;
+
 	void updateEnergy();
 signals:
 	void gpuNotSupported(const std::string &message);
 	void layoutChanged();
 	void positionChanged();
 public slots:
+	void initialize();
 	void clearPendula();
 	void addPendula(const std::vector<Pendulum *> &add);
 	void useGPUChanged(int);
 private slots:
 	void update();
 private:
+    QOpenGLFunctions_4_3_Core * f;
 	void updateGPUData();
 	struct GPULimits {
 		int maxWGCount[3];
@@ -59,5 +65,5 @@ private:
 	} SSBO;
 	QTimer * timer;
 	int updateInterval = 16;
-	bool useGPUAcceleration = false;
+	bool useGPUAcceleration = true;
 };

src/main.cpp

@@ -2,13 +2,14 @@
 #include <QSurfaceFormat>
 #include "MainWindow.h"
 #include <QIcon>
+#include <QThread>
 
 int main(int argc, char* argv[]) {
 	QSurfaceFormat fmt = QSurfaceFormat::defaultFormat();
 	fmt.setDepthBufferSize(24);
 	fmt.setSamples(8);
 	fmt.setSwapInterval(1);
-	fmt.setVersion(4, 3);
+	fmt.setVersion(3, 3);
 	fmt.setProfile(QSurfaceFormat::CoreProfile);
 	QSurfaceFormat::setDefaultFormat(fmt);
 
@@ -19,5 +20,7 @@ int main(int argc, char* argv[]) {
 	w.setWindowIcon(QIcon(":/icons/app_icon.ico"));
 	w.show();
 
+	w.simulationThread->start();
+
 	return QApplication::exec();
 }