Add 3D engine base class + window & offscreen implementations

Author: wonder-sk

src/3d/CMakeLists.txt

@@ -3,15 +3,18 @@
 
 SET(QGIS_3D_SRCS
   qgsaabb.cpp
+  qgsabstract3dengine.cpp
   qgs3dmapscene.cpp
   qgs3dmapsettings.cpp
   qgs3dutils.cpp
   qgscameracontroller.cpp
+  qgsoffscreen3dengine.cpp
   qgsphongmaterialsettings.cpp
   qgsraycastingutils_p.cpp
   qgstessellatedpolygongeometry.cpp
   qgstilingscheme.cpp
   qgsvectorlayer3drenderer.cpp
+  qgswindow3dengine.cpp
 
   chunks/qgschunkboundsentity_p.cpp
   chunks/qgschunkedentity_p.cpp
@@ -47,7 +50,10 @@ SET(QGIS_3D_MOC_HDRS
 
   qgs3dmapscene.h
   qgs3dmapsettings.h
+  qgsabstract3dengine.h
   qgscameracontroller.h
+  qgsoffscreen3dengine.h
+  qgswindow3dengine.h
 
   chunks/qgschunkedentity_p.h
   chunks/qgschunkloader_p.h
@@ -70,15 +76,18 @@ QT5_ADD_RESOURCES(QGIS_3D_RCC_SRCS shaders.qrc)
 
 SET(QGIS_3D_HDRS
   qgsaabb.h
+  qgsabstract3dengine.h
   qgs3dmapscene.h
   qgs3dmapsettings.h
   qgs3dutils.h
   qgscameracontroller.h
+  qgsoffscreen3dengine.h
   qgsphongmaterialsettings.h
   qgsraycastingutils_p.h
   qgstessellatedpolygongeometry.h
   qgstilingscheme.h
   qgsvectorlayer3drenderer.h
+  qgswindow3dengine.h
 
   chunks/qgschunkboundsentity_p.h
   chunks/qgschunkedentity_p.h

src/3d/qgs3dmapscene.cpp

@@ -29,6 +29,7 @@
 #include <QTimer>
 
 #include "qgsaabb.h"
+#include "qgsabstract3dengine.h"
 #include "qgs3dmapsettings.h"
 #include "qgs3dutils.h"
 #include "qgsabstract3drenderer.h"
@@ -41,27 +42,29 @@
 #include "qgsvectorlayer3drenderer.h"
 
 
-Qgs3DMapScene::Qgs3DMapScene( const Qgs3DMapSettings &map, Qt3DExtras::QForwardRenderer *defaultFrameGraph, Qt3DRender::QRenderSettings *renderSettings, Qt3DRender::QCamera *camera, const QRect &viewportRect, Qt3DCore::QNode *parent )
-  : Qt3DCore::QEntity( parent )
+Qgs3DMapScene::Qgs3DMapScene( const Qgs3DMapSettings &map, QgsAbstract3DEngine *engine )
+  : Qt3DCore::QEntity()
   , mMap( map )
-  , mForwardRenderer( defaultFrameGraph )
+  , mEngine( engine )
 {
 
   connect( &map, &Qgs3DMapSettings::backgroundColorChanged, this, &Qgs3DMapScene::onBackgroundColorChanged );
   onBackgroundColorChanged();
 
   // TODO: strange - setting OnDemand render policy still keeps QGIS busy (Qt 5.9.0)
   // actually it is more busy than with the default "Always" policy although there are no changes in the scene.
-  //renderSettings->setRenderPolicy( Qt3DRender::QRenderSettings::OnDemand );
+  //mRenderer->renderSettings()->setRenderPolicy( Qt3DRender::QRenderSettings::OnDemand );
 
 #if QT_VERSION >= 0x050900
   // we want precise picking of terrain (also bounding volume picking does not seem to work - not sure why)
-  renderSettings->pickingSettings()->setPickMethod( Qt3DRender::QPickingSettings::TrianglePicking );
+  mEngine->renderSettings()->pickingSettings()->setPickMethod( Qt3DRender::QPickingSettings::TrianglePicking );
 #endif
 
+  QRect viewportRect( QPoint( 0, 0 ), mEngine->size() );
+
   // Camera
   float aspectRatio = ( float )viewportRect.width() / viewportRect.height();
-  camera->lens()->setPerspectiveProjection( 45.0f, aspectRatio, 10.f, 10000.0f );
+  mEngine->camera()->lens()->setPerspectiveProjection( 45.0f, aspectRatio, 10.f, 10000.0f );
 
   mFrameAction = new Qt3DLogic::QFrameAction();
   connect( mFrameAction, &Qt3DLogic::QFrameAction::triggered,
@@ -71,10 +74,10 @@ Qgs3DMapScene::Qgs3DMapScene( const Qgs3DMapSettings &map, Qt3DExtras::QForwardR
   // Camera controlling
   mCameraController = new QgsCameraController( this ); // attaches to the scene
   mCameraController->setViewport( viewportRect );
-  mCameraController->setCamera( camera );
+  mCameraController->setCamera( mEngine->camera() );
   mCameraController->resetView( 1000 );
 
-  addCameraViewCenterEntity( camera );
+  addCameraViewCenterEntity( mEngine->camera() );
 
   // create terrain entity
 
@@ -156,7 +159,7 @@ Qgs3DMapScene::Qgs3DMapScene( const Qgs3DMapSettings &map, Qt3DExtras::QForwardR
     // docs say frustum culling must be disabled for skybox.
     // it _somehow_ works even when frustum culling is enabled with some camera positions,
     // but then when zoomed in more it would disappear - so let's keep frustum culling disabled
-    defaultFrameGraph->setFrustumCullingEnabled( false );
+    mEngine->setFrustumCullingEnabled( false );
   }
 
   // force initial update of chunked entities
@@ -333,7 +336,7 @@ void Qgs3DMapScene::createTerrainDeferred()
 
 void Qgs3DMapScene::onBackgroundColorChanged()
 {
-  mForwardRenderer->setClearColor( mMap.backgroundColor() );
+  mEngine->setClearColor( mMap.backgroundColor() );
 }
 
 void Qgs3DMapScene::onLayerRenderer3DChanged()

src/3d/qgs3dmapscene.h

@@ -36,6 +36,7 @@ namespace Qt3DExtras
   class QForwardRenderer;
 }
 
+class QgsAbstract3DEngine;
 class QgsMapLayer;
 class QgsCameraController;
 class Qgs3DMapSettings;
@@ -52,7 +53,7 @@ class _3D_EXPORT Qgs3DMapScene : public Qt3DCore::QEntity
     Q_OBJECT
   public:
     //! Constructs a 3D scene based on map settings and Qt 3D renderer configuration
-    Qgs3DMapScene( const Qgs3DMapSettings &map, Qt3DExtras::QForwardRenderer *defaultFrameGraph, Qt3DRender::QRenderSettings *renderSettings, Qt3DRender::QCamera *camera, const QRect &viewportRect, Qt3DCore::QNode *parent = nullptr );
+    Qgs3DMapScene( const Qgs3DMapSettings &map, QgsAbstract3DEngine *engine );
 
     //! Returns camera controller
     QgsCameraController *cameraController() { return mCameraController; }
@@ -87,12 +88,11 @@ class _3D_EXPORT Qgs3DMapScene : public Qt3DCore::QEntity
 
   private:
     const Qgs3DMapSettings &mMap;
+    QgsAbstract3DEngine *mEngine = nullptr;
     //! Provides a way to have a synchronous function executed each frame
     Qt3DLogic::QFrameAction *mFrameAction = nullptr;
     QgsCameraController *mCameraController = nullptr;
     QgsTerrainEntity *mTerrain = nullptr;
-    //! Forward renderer provided by 3D window
-    Qt3DExtras::QForwardRenderer *mForwardRenderer = nullptr;
     QList<QgsChunkedEntity *> mChunkEntities;
     //! Entity that shows view center - useful for debugging camera issues
     Qt3DCore::QEntity *mEntityCameraViewCenter = nullptr;

src/3d/qgsabstract3dengine.cpp

@@ -0,0 +1,16 @@
+/***************************************************************************
+  qgsabstract3dengine.cpp
+  --------------------------------------
+  Date                 : July 2018
+  Copyright            : (C) 2018 by Martin Dobias
+  Email                : wonder dot sk at gmail dot com
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "qgsabstract3dengine.h"

src/3d/qgsabstract3dengine.h

@@ -0,0 +1,52 @@
+#ifndef QGSABSTRACT3DENGINE_H
+#define QGSABSTRACT3DENGINE_H
+
+#include "qgis_3d.h"
+
+#include <QObject>
+
+class QColor;
+class QRect;
+
+namespace Qt3DCore
+{
+  class QEntity;
+}
+
+namespace Qt3DRender
+{
+  class QRenderSettings;
+  class QCamera;
+}
+
+/**
+ * Base class for 3D engine implementation. A 3D engine is responsible for setting up
+ * rendering with Qt3D. This means mainly:
+ * - creating Qt3D aspect engine and registering rendering aspect
+ * - setting up a camera, render settings and frame graph
+ *
+ * We have two implementations:
+ * - QgsWindow3DEngine - used for rendering on display (has a QWindow that can be embedded into QWidget)
+ * - QgsOffscreen3DEngine - renders scene to images
+ *
+ * \since QGIS 3.4
+ */
+class _3D_EXPORT QgsAbstract3DEngine : public QObject
+{
+    Q_OBJECT
+  public:
+
+    virtual void setClearColor( const QColor &color ) = 0;
+    virtual void setFrustumCullingEnabled( bool enabled ) = 0;
+    virtual void setRootEntity( Qt3DCore::QEntity *root ) = 0;
+
+    virtual Qt3DRender::QRenderSettings *renderSettings() = 0;
+    virtual Qt3DRender::QCamera *camera() = 0;
+    virtual QSize size() const = 0;
+
+  signals:
+    void imageCaptured( const QImage &image );
+};
+
+
+#endif // QGSABSTRACT3DENGINE_H