Improve 3D Map View movement performance

src/3d/qgs3dmapscene.cpp

@@ -334,8 +334,7 @@ void Qgs3DMapScene::updateScene( bool forceUpdate )
     return;
   }
 
-  if ( forceUpdate )
-    QgsEventTracing::addEvent( QgsEventTracing::Instant, QStringLiteral( "3D" ), QStringLiteral( "Update Scene" ) );
+  QgsEventTracing::ScopedEvent traceEvent( QStringLiteral( "3D" ), forceUpdate ? QStringLiteral( "Force update scene" ) : QStringLiteral( "Update scene" ) );
 
   Qgs3DMapSceneEntity::SceneContext sceneContext;
   Qt3DRender::QCamera *camera = mEngine->camera();
@@ -421,6 +420,8 @@ bool Qgs3DMapScene::updateCameraNearFarPlanes()
 
 void Qgs3DMapScene::onFrameTriggered( float dt )
 {
+  QgsEventTracing::addEvent( QgsEventTracing::EventType::Instant, QStringLiteral( "3D" ), QStringLiteral( "Frame begins" ) );
+
   mCameraController->frameTriggered( dt );
 
   updateScene();

src/3d/qgs3dutils.cpp

@@ -45,6 +45,7 @@
 #include <Qt3DRender/QRenderSettings>
 #include <QOpenGLContext>
 #include <QOpenGLFunctions>
+#include <Qt3DLogic/QFrameAction>
 
 
 #if QT_VERSION < QT_VERSION_CHECK( 6, 0, 0 )
@@ -58,6 +59,24 @@ typedef Qt3DCore::QBuffer Qt3DQBuffer;
 // declared here as Qgs3DTypes has no cpp file
 const char *Qgs3DTypes::PROP_NAME_3D_RENDERER_FLAG = "PROP_NAME_3D_RENDERER_FLAG";
 
+void Qgs3DUtils::waitForFrame( QgsAbstract3DEngine &engine, Qgs3DMapScene *scene )
+{
+  // Set policy to always render frame, so we don't wait forever.
+  Qt3DRender::QRenderSettings::RenderPolicy oldPolicy = engine.renderSettings()->renderPolicy();
+  engine.renderSettings()->setRenderPolicy( Qt3DRender::QRenderSettings::RenderPolicy::Always );
+
+  // Wait for at least one frame to render
+  Qt3DLogic::QFrameAction *frameAction = new Qt3DLogic::QFrameAction();
+  scene->addComponent( frameAction );
+  QEventLoop evLoop;
+  QObject::connect( frameAction, &Qt3DLogic::QFrameAction::triggered, &evLoop, &QEventLoop::quit );
+  evLoop.exec();
+  scene->removeComponent( frameAction );
+  frameAction->deleteLater();
+
+  engine.renderSettings()->setRenderPolicy( oldPolicy );
+}
+
 QImage Qgs3DUtils::captureSceneImage( QgsAbstract3DEngine &engine, Qgs3DMapScene *scene )
 {
   QImage resImage;
@@ -66,13 +85,7 @@ QImage Qgs3DUtils::captureSceneImage( QgsAbstract3DEngine &engine, Qgs3DMapScene
   // We need to change render policy to RenderPolicy::Always, since otherwise render capture node won't work
   engine.renderSettings()->setRenderPolicy( Qt3DRender::QRenderSettings::RenderPolicy::Always );
 
-  auto requestImageFcn = [&engine, scene] {
-    if ( scene->sceneState() == Qgs3DMapScene::Ready )
-    {
-      engine.renderSettings()->setRenderPolicy( Qt3DRender::QRenderSettings::RenderPolicy::OnDemand );
-      engine.requestCaptureImage();
-    }
-  };
+  waitForFrame( engine, scene );
 
   auto saveImageFcn = [&evLoop, &resImage]( const QImage &img ) {
     resImage = img;
@@ -82,6 +95,14 @@ QImage Qgs3DUtils::captureSceneImage( QgsAbstract3DEngine &engine, Qgs3DMapScene
   const QMetaObject::Connection conn1 = QObject::connect( &engine, &QgsAbstract3DEngine::imageCaptured, saveImageFcn );
   QMetaObject::Connection conn2;
 
+  auto requestImageFcn = [&engine, scene] {
+    if ( scene->sceneState() == Qgs3DMapScene::Ready )
+    {
+      engine.renderSettings()->setRenderPolicy( Qt3DRender::QRenderSettings::RenderPolicy::OnDemand );
+      engine.requestCaptureImage();
+    }
+  };
+
   if ( scene->sceneState() == Qgs3DMapScene::Ready )
   {
     requestImageFcn();
@@ -126,6 +147,8 @@ QImage Qgs3DUtils::captureSceneDepthBuffer( QgsAbstract3DEngine &engine, Qgs3DMa
   QMetaObject::Connection conn1 = QObject::connect( &engine, &QgsAbstract3DEngine::depthBufferCaptured, saveImageFcn );
   QMetaObject::Connection conn2;
 
+  // Make sure once-per-frame functions run
+  waitForFrame( engine, scene );
   if ( scene->sceneState() == Qgs3DMapScene::Ready )
   {
     requestImageFcn();

src/3d/qgs3dutils.h

@@ -65,6 +65,12 @@ class _3D_EXPORT Qgs3DUtils
      */
     static QImage captureSceneImage( QgsAbstract3DEngine &engine, Qgs3DMapScene *scene );
 
+    /**
+     * Waits for a frame to be rendered. Useful to trigger once-per-frame updates
+     * \since QGIS 3.42
+     */
+    static void waitForFrame( QgsAbstract3DEngine &engine, Qgs3DMapScene *scene );
+
     /**
      * Captures the depth buffer of the current 3D scene of a 3D engine. The function waits
      * until the scene is not fully loaded/updated before capturing the image.

src/3d/qgscameracontroller.cpp

@@ -15,6 +15,7 @@
 
 #include "qgscameracontroller.h"
 #include "moc_qgscameracontroller.cpp"
+#include "qgseventtracing.h"
 #include "qgsvector3d.h"
 #include "qgswindow3dengine.h"
 #include "qgs3dmapscene.h"
@@ -161,6 +162,12 @@ void QgsCameraController::zoomCameraAroundPivot( const QVector3D &oldCameraPosit
 void QgsCameraController::frameTriggered( float dt )
 {
   Q_UNUSED( dt )
+
+  if ( mCameraChanged )
+  {
+    emit cameraChanged();
+    mCameraChanged = false;
+  }
 }
 
 void QgsCameraController::resetView( float distance )
@@ -233,7 +240,7 @@ void QgsCameraController::readXml( const QDomElement &elem )
   setLookingAtPoint( QgsVector3D( x, elev, y ), dist, pitch, yaw );
 }
 
-double QgsCameraController::sampleDepthBuffer( const QImage &buffer, int px, int py )
+double QgsCameraController::sampleDepthBuffer( int px, int py )
 {
   double depth = 1;
 
@@ -242,24 +249,31 @@ double QgsCameraController::sampleDepthBuffer( const QImage &buffer, int px, int
   {
     for ( int y = py - 3; y <= py + 3; ++y )
     {
-      if ( buffer.valid( x, y ) )
+      if ( mDepthBufferImage.valid( x, y ) )
       {
-        depth = std::min( depth, Qgs3DUtils::decodeDepth( buffer.pixel( x, y ) ) );
+        depth = std::min( depth, Qgs3DUtils::decodeDepth( mDepthBufferImage.pixel( x, y ) ) );
       }
     }
   }
 
   if ( depth < 1 )
     return depth;
 
+  // Cache the computed depth, since averaging over all pixels can be expensive
+  if ( mDepthBufferNonVoidAverage != -1 )
+    return mDepthBufferNonVoidAverage;
+
   // Returns the average of depth values that are not 1 (void area)
   depth = 0;
   int samplesCount = 0;
-  for ( int x = 0; x < buffer.width(); ++x )
+  // Make sure we can do the cast
+  Q_ASSERT( mDepthBufferImage.format() == QImage::Format_RGB32 );
+  for ( int y = 0; y < mDepthBufferImage.height(); ++y )
   {
-    for ( int y = 0; y < buffer.height(); ++y )
+    const QRgb *line = reinterpret_cast<const QRgb *>( mDepthBufferImage.constScanLine( y ) );
+    for ( int x = 0; x < mDepthBufferImage.width(); ++x )
     {
-      double d = Qgs3DUtils::decodeDepth( buffer.pixel( x, y ) );
+      double d = Qgs3DUtils::decodeDepth( line[x] );
       if ( d < 1 )
       {
         depth += d;
@@ -274,6 +288,8 @@ double QgsCameraController::sampleDepthBuffer( const QImage &buffer, int px, int
   else
     depth /= samplesCount;
 
+  mDepthBufferNonVoidAverage = depth;
+
   return depth;
 }
 
@@ -282,7 +298,7 @@ void QgsCameraController::updateCameraFromPose()
   if ( mCamera )
     mCameraPose.updateCamera( mCamera );
 
-  emit cameraChanged();
+  mCameraChanged = true;
 }
 
 void QgsCameraController::moveCameraPositionBy( const QVector3D &posDiff )
@@ -296,6 +312,8 @@ void QgsCameraController::onPositionChanged( Qt3DInput::QMouseEvent *mouse )
   if ( !mInputHandlersEnabled )
     return;
 
+  QgsEventTracing::ScopedEvent traceEvent( QStringLiteral( "3D" ), QStringLiteral( "QgsCameraController::onPositionChanged" ) );
+
   switch ( mCameraNavigationMode )
   {
     case Qgis::NavigationMode::TerrainBased:
@@ -310,7 +328,7 @@ void QgsCameraController::onPositionChanged( Qt3DInput::QMouseEvent *mouse )
 
 bool QgsCameraController::screenPointToWorldPos( QPoint position, Qt3DRender::QCamera *mCameraBefore, double &depth, QVector3D &worldPosition )
 {
-  depth = sampleDepthBuffer( mDepthBufferImage, position.x(), position.y() );
+  depth = sampleDepthBuffer( position.x(), position.y() );
   if ( !std::isfinite( depth ) )
   {
     QgsDebugMsgLevel( QStringLiteral( "screenPointToWorldPos: depth is NaN or Inf. This should not happen." ), 2 );
@@ -557,6 +575,7 @@ void QgsCameraController::onWheel( Qt3DInput::QWheelEvent *wheel )
       if ( mCurrentOperation != MouseOperation::ZoomWheel )
       {
         setMouseParameters( MouseOperation::ZoomWheel );
+        // The actual zooming will happen after we get a new depth buffer
       }
       else
       {
@@ -1017,6 +1036,7 @@ void QgsCameraController::depthBufferCaptured( const QImage &depthImage )
 {
   mDepthBufferImage = depthImage;
   mDepthBufferIsReady = true;
+  mDepthBufferNonVoidAverage = -1;
 
   if ( mCurrentOperation == MouseOperation::ZoomWheel )
   {

src/3d/qgscameracontroller.h

@@ -326,7 +326,7 @@ class _3D_EXPORT QgsCameraController : public QObject
      * Returns the minimum depth value in the square [px - 3, px + 3] * [py - 3, py + 3]
      * If the value is 1, the average depth of all non void pixels is returned instead.
      */
-    double sampleDepthBuffer( const QImage &buffer, int px, int py );
+    double sampleDepthBuffer( int px, int py );
 
 #ifndef SIP_RUN
     //! Converts screen point to world position
@@ -350,6 +350,9 @@ class _3D_EXPORT QgsCameraController : public QObject
 
     bool mDepthBufferIsReady = false;
     QImage mDepthBufferImage;
+    // -1 when unset
+    // TODO: Change to std::optional<double>
+    double mDepthBufferNonVoidAverage = -1;
 
     std::unique_ptr<Qt3DRender::QCamera> mCameraBefore;
 
@@ -385,6 +388,9 @@ class _3D_EXPORT QgsCameraController : public QObject
     // 3D world's origin in map coordinates
     QgsVector3D mOrigin;
 
+    //! Did camera change since last frame? Need to know if we should emit cameraChanged().
+    bool mCameraChanged = false;
+
     // To test the cameracontroller
     friend class TestQgs3DRendering;
     friend class TestQgs3DCameraController;

tests/src/3d/testqgs3dcameracontroller.cpp

@@ -52,6 +52,8 @@ class TestQgs3DCameraController : public QgsTest
     void testRotationCenterRotationCameraRotationCenter();
 
   private:
+    void waitForNearPlane( QgsOffscreen3DEngine &engine, Qgs3DMapScene *scene, float atLeast ); //#spellok
+
     QgsRasterLayer *mLayerRgb = nullptr;
     QgsVectorLayer *mLayerBuildings = nullptr;
 };
@@ -455,14 +457,13 @@ void TestQgs3DCameraController::testRotationCenterZoomWheelRotationCenter()
 
   // look from the top
   scene->cameraController()->setLookingAtPoint( QgsVector3D( 0, 0, 0 ), 2500, 0, 0 );
+  waitForNearPlane( engine, scene, 1000 );
+
   QVector3D initialCamViewCenter = scene->cameraController()->camera()->viewCenter();
   QVector3D initialCamPosition = scene->cameraController()->camera()->position();
   float initialPitch = scene->cameraController()->pitch();
   float initialYaw = scene->cameraController()->yaw();
 
-  // this call is not used but ensures to synchronize the scene
-  Qgs3DUtils::captureSceneImage( engine, scene );
-
   QMouseEvent mousePressEvent( QEvent::MouseButtonPress, midPos, Qt::LeftButton, Qt::LeftButton, Qt::ShiftModifier );
   scene->cameraController()->onMousePressed( new Qt3DInput::QMouseEvent( mousePressEvent ) );
 
@@ -522,9 +523,9 @@ void TestQgs3DCameraController::testRotationCenterZoomWheelRotationCenter()
   depthImage = Qgs3DUtils::captureSceneDepthBuffer( engine, scene );
   scene->cameraController()->depthBufferCaptured( depthImage );
 
-  QGSCOMPARENEARVECTOR3D( scene->cameraController()->mZoomPoint, QVector3D( 283.2, -923.1, -27.0 ), 1.5 );
-  QGSCOMPARENEARVECTOR3D( scene->cameraController()->cameraPose().centerPoint(), QVector3D( 99.4, -319.9, -8.8 ), 2.0 );
-  QGSCOMPARENEAR( scene->cameraController()->cameraPose().distanceFromCenterPoint(), 1631.9, 2.0 );
+  QGSCOMPARENEARVECTOR3D( scene->cameraController()->mZoomPoint, QVector3D( 312.936, -950.772, -125.381 ), 3.0 );
+  QGSCOMPARENEARVECTOR3D( scene->cameraController()->cameraPose().centerPoint(), QVector3D( 109.8, -329.4, -43.3 ), 3.0 );
+  QGSCOMPARENEAR( scene->cameraController()->cameraPose().distanceFromCenterPoint(), 1631.9, 3.0 );
   QCOMPARE( scene->cameraController()->pitch(), initialPitch );
   QCOMPARE( scene->cameraController()->yaw(), initialYaw );
   QCOMPARE( scene->cameraController()->mCumulatedWheelY, 0 );
@@ -540,6 +541,7 @@ void TestQgs3DCameraController::testRotationCenterZoomWheelRotationCenter()
   initialPitch = scene->cameraController()->pitch();
   initialYaw = scene->cameraController()->yaw();
 
+  Qgs3DUtils::waitForFrame( engine, scene );
   // the first mouse event only updates the mouse position
   // the second one will update the camera
   QMouseEvent mouseMoveEvent3( QEvent::MouseMove, midPos + movement1 + movement2, Qt::LeftButton, Qt::LeftButton, Qt::ShiftModifier );
@@ -558,9 +560,9 @@ void TestQgs3DCameraController::testRotationCenterZoomWheelRotationCenter()
   QCOMPARE( scene->cameraController()->mCurrentOperation, QgsCameraController::MouseOperation::RotationCenter );
 
   diffViewCenter = scene->cameraController()->camera()->viewCenter() - initialCamViewCenter;
-  QGSCOMPARENEARVECTOR3D( diffViewCenter, QVector3D( 25.9, 7.1, 5.2 ), 1.0 );
+  QGSCOMPARENEARVECTOR3D( diffViewCenter, QVector3D( 26.9, 7.3, 5.4 ), 2.0 );
   diffPosition = scene->cameraController()->camera()->position() - initialCamPosition;
-  QGSCOMPARENEARVECTOR3D( diffPosition, QVector3D( -44.3, -9.1, -11.7 ), 1.0 );
+  QGSCOMPARENEARVECTOR3D( diffPosition, QVector3D( -43.2, -9.1, -11.1 ), 1.0 );
   diffPitch = scene->cameraController()->pitch() - initialPitch;
   diffYaw = scene->cameraController()->yaw() - initialYaw;
   QGSCOMPARENEAR( diffPitch, 2.5, 0.1 );
@@ -598,14 +600,13 @@ void TestQgs3DCameraController::testTranslateRotationCenterTranslate()
 
   // look from the top
   scene->cameraController()->setLookingAtPoint( QgsVector3D( 0, 0, 0 ), 2500, 0, 0 );
+  waitForNearPlane( engine, scene, 1000 );
+
   QVector3D initialCamViewCenter = scene->cameraController()->camera()->viewCenter();
   QVector3D initialCamPosition = scene->cameraController()->camera()->position();
   float initialPitch = scene->cameraController()->pitch();
   float initialYaw = scene->cameraController()->yaw();
 
-  // this call is not used but ensures to synchronize the scene
-  Qgs3DUtils::captureSceneImage( engine, scene );
-
   //
   // 1. Translate
   //
@@ -751,14 +752,12 @@ void TestQgs3DCameraController::testTranslateZoomWheelTranslate()
 
   // look from the top
   scene->cameraController()->setLookingAtPoint( QgsVector3D( 0, 0, 0 ), 2500, 0, 0 );
+  waitForNearPlane( engine, scene, 1000 );
   QVector3D initialCamViewCenter = scene->cameraController()->camera()->viewCenter();
   QVector3D initialCamPosition = scene->cameraController()->camera()->position();
   float initialPitch = scene->cameraController()->pitch();
   float initialYaw = scene->cameraController()->yaw();
 
-  // this call is not used but ensures to synchronize the scene
-  Qgs3DUtils::captureSceneImage( engine, scene );
-
   //
   // 1. Translate
   //
@@ -857,9 +856,9 @@ void TestQgs3DCameraController::testTranslateZoomWheelTranslate()
   QCOMPARE( scene->cameraController()->mCurrentOperation, QgsCameraController::MouseOperation::Translation );
 
   diffViewCenter = scene->cameraController()->camera()->viewCenter() - initialCamViewCenter;
-  QGSCOMPARENEARVECTOR3D( diffViewCenter, QVector3D( -11.3, 11.3, 0.0 ), 1.0 );
+  QGSCOMPARENEARVECTOR3D( diffViewCenter, QVector3D( -17.2, 17.2, 0.0 ), 1.0 );
   diffPosition = scene->cameraController()->camera()->position() - initialCamPosition;
-  QGSCOMPARENEARVECTOR3D( diffPosition, QVector3D( -11.3, 11.3, 0.0 ), 1.0 );
+  QGSCOMPARENEARVECTOR3D( diffPosition, QVector3D( -17.2, 17.2, 0.0 ), 1.0 );
   QCOMPARE( scene->cameraController()->pitch(), initialPitch );
   QCOMPARE( scene->cameraController()->yaw(), initialYaw );
 
@@ -1173,5 +1172,23 @@ void TestQgs3DCameraController::testRotationCenterRotationCameraRotationCenter()
   mapSettings->setLayers( {} );
 }
 
+void TestQgs3DCameraController::waitForNearPlane( QgsOffscreen3DEngine &engine, Qgs3DMapScene *scene, float atLeast ) //#spellok
+{
+  // XXX: Sometimes the near/far planes aren't calculated correctly, so they're
+  // left at the too-deep default. This causes the rest of the test to fail in
+  // weird ways every once in a while, so loop until we get good values.
+  size_t i = 0;
+  do
+  {
+    QVERIFY2( i++ < 10, "Near plane not set properly even after multiple tries" );
+
+    // Force recalcualtion of near/far planes.
+    scene->cameraController()->mCameraChanged = true;
+
+    // this call is not used but ensures to synchronize the scene
+    Qgs3DUtils::captureSceneImage( engine, scene );
+  } while ( scene->cameraController()->camera()->nearPlane() < atLeast ); //#spellok
+}
+
 QGSTEST_MAIN( TestQgs3DCameraController )
 #include "testqgs3dcameracontroller.moc"