Disable RHI Renderer by default

RHI renderer use ShaderTools which is GPL licensed. This patch
disables the plugin by default until Qt3D provides a suitable
replacement for the dependency.

To enable the RHI backend, compile Qt3D and pass parameter
-DFEATURE_qt3d_rhi_renderer=ON to cmake.

Unfortunate side effect of RHI backend being disabled is that
when using Scene3D, the QtQuick renderer must be configured to
use the opengl backend.

[ChangeLog] RHI Backend is not longer built by default

Task-number: QTBUG-94960
Pick-to: 6.1 6.2
Change-Id: I0bff7523e159b800734b58bfef37e5088d0a0d41
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

5 files changed, 24 insertions, 6 deletions

diff --git a/src/extras/defaults/qt3dwindow.cpp b/src/extras/defaults/qt3dwindow.cpp
index 2798fab17..04a0c5b5a 100644
--- a/src/extras/defaults/qt3dwindow.cpp
+++ b/src/extras/defaults/qt3dwindow.cpp
@@ -62,6 +62,7 @@
 #include <Qt3DLogic/qlogicaspect.h>
 #include <Qt3DRender/qcamera.h>
 #include <Qt3DRender/private/vulkaninstance_p.h>
+#include <Qt3DRender/qt3drender-config.h>
 #include <qopenglcontext.h>
 #include <private/qrendersettings_p.h>
 
@@ -278,13 +279,15 @@ void setupWindowSurface(QWindow *window, Qt3DRender::API api) noexcept
     // backend is in use will get a valid value.
     bool useRhi = false;
     if (qEnvironmentVariableIsEmpty("QT3D_RENDERER")) {
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
+#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0) && QT_CONFIG(qt3d_rhi_renderer)
         qputenv("QT3D_RENDERER", "rhi");
 #else
         qputenv("QT3D_RENDERER", "opengl");
 #endif
     }
+#if QT_CONFIG(qt3d_rhi_renderer)
     useRhi = qEnvironmentVariable("QT3D_RENDERER") == QStringLiteral("rhi");
+#endif
 
     if (!useRhi)
         api = Qt3DRender::API::OpenGL;
diff --git a/src/plugins/renderers/CMakeLists.txt b/src/plugins/renderers/CMakeLists.txt
index bf6242083..9caeb4153 100644
--- a/src/plugins/renderers/CMakeLists.txt
+++ b/src/plugins/renderers/CMakeLists.txt
@@ -11,6 +11,6 @@ qt_feature_module_end(NO_MODULE)
 if(QT_FEATURE_qt3d_opengl_renderer)
     add_subdirectory(opengl)
 endif()
-if(QT_FEATURE_qt3d_rhi_renderer AND TARGET Qt::ShaderTools)
+if(QT_FEATURE_qt3d_rhi_renderer)
     add_subdirectory(rhi)
 endif()
diff --git a/src/plugins/renderers/rhi/CMakeLists.txt b/src/plugins/renderers/rhi/CMakeLists.txt
index 270294ab4..f9664a995 100644
--- a/src/plugins/renderers/rhi/CMakeLists.txt
+++ b/src/plugins/renderers/rhi/CMakeLists.txt
@@ -36,6 +36,8 @@ if(QT_FEATURE_private_tests)
         textures
     )
 
+    find_package(Qt6 REQUIRED COMPONENTS ShaderTools)
+
     target_link_libraries(RhiRendererLib
         PUBLIC
             Qt::3DCore
diff --git a/src/quick3d/imports/scene3d/scene3ditem.cpp b/src/quick3d/imports/scene3d/scene3ditem.cpp
index 5ba3c6a7c..6f84fff7e 100644
--- a/src/quick3d/imports/scene3d/scene3ditem.cpp
+++ b/src/quick3d/imports/scene3d/scene3ditem.cpp
@@ -68,6 +68,7 @@
 #include <Qt3DRender/private/qrendersurfaceselector_p.h>
 #include <Qt3DRender/private/qrenderaspect_p.h>
 #include <Qt3DRender/private/rendersettings_p.h>
+#include <Qt3DRender/qt3drender-config.h>
 #include <scene3dlogging_p.h>
 #include <scene3drenderer_p.h>
 #include <scene3dsgnode_p.h>
@@ -198,7 +199,7 @@ Scene3DItem::Scene3DItem(QQuickItem *parent)
     setHeight(1);
 
     if (qgetenv("QT3D_RENDERER").isEmpty()) {
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
+#if QT_CONFIG(qt3d_rhi_renderer)
         qputenv("QT3D_RENDERER", "rhi"); // QtQuick requires RHI
 #else
         qputenv("QT3D_RENDERER", "opengl"); // QtQuick requires OpenGL
@@ -829,6 +830,17 @@ QSGNode *Scene3DItem::updatePaintNode(QSGNode *node, QQuickItem::UpdatePaintNode
         auto renderAspectPriv = static_cast<QRenderAspectPrivate*>(QRenderAspectPrivate::get(renderAspect));
         renderAspectPriv->m_screen = (rw ? rw->screen() : window()->screen());
         updateWindowSurface();
+
+#if !QT_CONFIG(qt3d_rhi_renderer)
+        QSGRendererInterface::GraphicsApi windowApi = window()->rendererInterface()->graphicsApi();
+
+        if (windowApi != QSGRendererInterface::OpenGLRhi &&
+            windowApi != QSGRendererInterface::OpenGL) {
+
+            qFatal("Qt3D's RHI Renderer is not enabled, please configure RHI to use the OpenGL backend "
+                   "by calling qputenv(\"QSG_RHI_BACKEND\", \"opengl\")");
+        }
+#endif
         managerNode->init();
         // Note: ChangeArbiter is only set after aspect was registered
         QObject::connect(
diff --git a/src/render/configure.cmake b/src/render/configure.cmake
index 6aa29b5d4..9fb7183d9 100644
--- a/src/render/configure.cmake
+++ b/src/render/configure.cmake
@@ -16,15 +16,16 @@ endif()
 
 #### Features
 
-qt_feature("qt3d-opengl-renderer" PRIVATE
+qt_feature("qt3d-opengl-renderer" PUBLIC
     SECTION "Qt 3D Renderers"
     LABEL "OpenGL Renderer"
     PURPOSE "Use the OpenGL renderer"
 )
-qt_feature("qt3d-rhi-renderer" PRIVATE
+qt_feature("qt3d-rhi-renderer" PUBLIC
     SECTION "Qt 3D Renderers"
     LABEL "RHI Renderer"
-    PURPOSE "Use the RHI renderer"
+    PURPOSE "Use the RHI renderer (requires qtShaderTools module)"
+    AUTODETECT false
 )
 qt_feature("qt3d-vulkan" PUBLIC
     LABEL "Vulkan"