From c7b6a115df1b25d1fc623dd3d7a15e2ceb3428a9 Mon Sep 17 00:00:00 2001
From: Nyall Dawson <nyall.dawson@gmail.com>
Date: Wed, 15 Jul 2020 11:14:28 +1000
Subject: [PATCH] Better initialization of 3d framework, usable outside of app

---
 python/3d/auto_generated/qgs3d.sip.in |  5 +++++
 src/3d/qgs3d.cpp                      | 21 +++++++++++++++++++++
 src/3d/qgs3d.h                        |  7 +++++++
 src/app/qgisapp.cpp                   | 12 +++---------
 4 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/python/3d/auto_generated/qgs3d.sip.in b/python/3d/auto_generated/qgs3d.sip.in
index 180660b15499..5f9315bc59d6 100644
--- a/python/3d/auto_generated/qgs3d.sip.in
+++ b/python/3d/auto_generated/qgs3d.sip.in
@@ -32,6 +32,11 @@ Returns a pointer to the singleton instance.
 
     ~Qgs3D();
 
+    static void initialize();
+%Docstring
+Initializes the 3D framework.
+%End
+
   private:
     Qgs3D( const Qgs3D &other );
 };
diff --git a/src/3d/qgs3d.cpp b/src/3d/qgs3d.cpp
index 507ba886c90f..78e8ebfc2b67 100644
--- a/src/3d/qgs3d.cpp
+++ b/src/3d/qgs3d.cpp
@@ -17,6 +17,15 @@
 
 #include "qgs3d.h"
 
+#include "qgsapplication.h"
+#include "qgs3drendererregistry.h"
+
+#include "qgsabstract3drenderer.h"
+#include "qgs3drendererregistry.h"
+#include "qgsrulebased3drenderer.h"
+#include "qgsvectorlayer3drenderer.h"
+#include "qgsmeshlayer3drenderer.h"
+
 Qgs3D *Qgs3D::instance()
 {
   static Qgs3D *sInstance( new Qgs3D() );
@@ -27,6 +36,18 @@ Qgs3D::~Qgs3D()
 {
 }
 
+void Qgs3D::initialize()
+{
+  if ( instance()->mInitialized )
+    return;
+
+  instance()->mInitialized = true;
+
+  QgsApplication::renderer3DRegistry()->addRenderer( new QgsVectorLayer3DRendererMetadata );
+  QgsApplication::renderer3DRegistry()->addRenderer( new QgsRuleBased3DRendererMetadata );
+  QgsApplication::renderer3DRegistry()->addRenderer( new QgsMeshLayer3DRendererMetadata );
+}
+
 Qgs3D::Qgs3D()
 {
 }
diff --git a/src/3d/qgs3d.h b/src/3d/qgs3d.h
index 97346bb8a99b..81c0590ac144 100644
--- a/src/3d/qgs3d.h
+++ b/src/3d/qgs3d.h
@@ -45,6 +45,11 @@ class _3D_EXPORT Qgs3D
 
     ~Qgs3D();
 
+    /**
+     * Initializes the 3D framework.
+     */
+    static void initialize();
+
   private:
 
     Qgs3D();
@@ -53,6 +58,8 @@ class _3D_EXPORT Qgs3D
     Qgs3D( const Qgs3D &other );
 #endif
 
+    bool mInitialized = false;
+
 };
 
 #endif // QGS3D_H
diff --git a/src/app/qgisapp.cpp b/src/app/qgisapp.cpp
index 82d3dc0e744e..4890f24469d6 100644
--- a/src/app/qgisapp.cpp
+++ b/src/app/qgisapp.cpp
@@ -97,19 +97,15 @@
 #include "qgsgeometrycheckregistry.h"
 
 #ifdef HAVE_3D
-#include "qgsabstract3drenderer.h"
+#include "qgs3d.h"
 #include "qgs3danimationsettings.h"
 #include "qgs3danimationwidget.h"
 #include "qgs3dmapcanvasdockwidget.h"
-#include "qgs3drendererregistry.h"
 #include "qgs3dmapcanvas.h"
 #include "qgs3dmapsettings.h"
 #include "qgscameracontroller.h"
 #include "qgsflatterraingenerator.h"
 #include "qgslayoutitem3dmap.h"
-#include "qgsrulebased3drenderer.h"
-#include "qgsvectorlayer3drenderer.h"
-#include "qgsmeshlayer3drenderer.h"
 #include "processing/qgs3dalgorithms.h"
 #include "qgs3dmaptoolmeasureline.h"
 #include "layout/qgslayout3dmapwidget.h"
@@ -12655,10 +12651,8 @@ void QgisApp::newMapCanvas()
 void QgisApp::init3D()
 {
 #ifdef HAVE_3D
-  // register 3D renderers
-  QgsApplication::instance()->renderer3DRegistry()->addRenderer( new QgsVectorLayer3DRendererMetadata );
-  QgsApplication::instance()->renderer3DRegistry()->addRenderer( new QgsRuleBased3DRendererMetadata );
-  QgsApplication::instance()->renderer3DRegistry()->addRenderer( new QgsMeshLayer3DRendererMetadata );
+  // initialize 3D registries
+  Qgs3D::initialize();
 #else
   mActionNew3DMapCanvas->setVisible( false );
 #endif