Remove OpenGL FBO references in QQuickWindow and the renderer API

setRenderTarget(GLuint), setRenderTarget(QQuickFramebufferObject*),
renderScene(uint fboId), QSGBindable, etc. are now removed.

This leads to a simpler and cleaner interface in QSGAbstractRenderer and
QSGRenderer because the somewhat weird renderScene() overloading (where
one version is virtual, while the other isn't) is now avoided, with just
a single renderScene() virtual now.

Task-number: QTBUG-84040
Change-Id: I0ce5a159a557688bdfcb7cacf8a9d12d6fd970d1
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

15 files changed, 23 insertions, 159 deletions

diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwarecontext.cpp b/src/quick/scenegraph/adaptations/software/qsgsoftwarecontext.cpp
index 91c26780b1..4cb016562f 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwarecontext.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwarecontext.cpp
@@ -157,9 +157,9 @@ QSGRenderer *QSGSoftwareRenderContext::createRenderer()
 }
 
 
-void QSGSoftwareRenderContext::renderNextFrame(QSGRenderer *renderer, uint fbo)
+void QSGSoftwareRenderContext::renderNextFrame(QSGRenderer *renderer)
 {
-    renderer->renderScene(fbo);
+    renderer->renderScene();
 }
 
 int QSGSoftwareRenderContext::maxTextureSize() const
diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwarecontext_p.h b/src/quick/scenegraph/adaptations/software/qsgsoftwarecontext_p.h
index 84f468ce33..22f64bc70c 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwarecontext_p.h
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwarecontext_p.h
@@ -72,7 +72,7 @@ public:
     QSGSoftwareRenderContext(QSGContext *ctx);
     void initializeIfNeeded();
     void invalidate() override;
-    void renderNextFrame(QSGRenderer *renderer, uint fbo) override;
+    void renderNextFrame(QSGRenderer *renderer) override;
     QSGTexture *createTexture(const QImage &image, uint flags = CreateTexture_Alpha) const override;
     QSGRenderer *createRenderer() override;
     int maxTextureSize() const override;
diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer.cpp b/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer.cpp
index 4a6d73ec59..bdb23656fd 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer.cpp
@@ -59,14 +59,9 @@ QSGSoftwarePixmapRenderer::~QSGSoftwarePixmapRenderer()
 
 }
 
-void QSGSoftwarePixmapRenderer::renderScene(uint)
+void QSGSoftwarePixmapRenderer::renderScene()
 {
-    class B : public QSGBindable
-    {
-    public:
-        void bind() const override { }
-    } bindable;
-    QSGRenderer::renderScene(bindable);
+    QSGRenderer::renderScene();
 }
 
 void QSGSoftwarePixmapRenderer::render()
diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer_p.h b/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer_p.h
index 3b4fb304e7..2d042dae41 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer_p.h
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwarepixmaprenderer_p.h
@@ -61,7 +61,7 @@ public:
     QSGSoftwarePixmapRenderer(QSGRenderContext *context);
     virtual ~QSGSoftwarePixmapRenderer();
 
-    void renderScene(uint fboId = 0) final;
+    void renderScene() final;
     void render() final;
 
     void render(QPaintDevice *target);
diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp b/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp
index df129cbfee..af12df26ab 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp
@@ -85,14 +85,9 @@ QRegion QSGSoftwareRenderer::flushRegion() const
     return m_flushRegion;
 }
 
-void QSGSoftwareRenderer::renderScene(uint)
+void QSGSoftwareRenderer::renderScene()
 {
-    class B : public QSGBindable
-    {
-    public:
-        void bind() const override { }
-    } bindable;
-    QSGRenderer::renderScene(bindable);
+    QSGRenderer::renderScene();
 }
 
 void QSGSoftwareRenderer::render()
diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer_p.h b/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer_p.h
index bb28da4ca5..3730625a54 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer_p.h
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer_p.h
@@ -70,7 +70,7 @@ public:
     QRegion flushRegion() const;
 
 protected:
-    void renderScene(uint fboId = 0) final;
+    void renderScene() final;
     void render() final;
 
 private:
diff --git a/src/quick/scenegraph/coreapi/qsgabstractrenderer.cpp b/src/quick/scenegraph/coreapi/qsgabstractrenderer.cpp
index 502ee27e27..dba1d8406a 100644
--- a/src/quick/scenegraph/coreapi/qsgabstractrenderer.cpp
+++ b/src/quick/scenegraph/coreapi/qsgabstractrenderer.cpp
@@ -79,17 +79,9 @@ QT_BEGIN_NAMESPACE
  */
 
 /*!
-    \fn void QSGAbstractRenderer::renderScene(GLuint fboId = 0)
+    \fn void QSGAbstractRenderer::renderScene()
 
-    Render the scene to the specified \a fboId
-
-    If \a fboId isn't specified, the scene graph will be rendered
-    to the default framebuffer. You will have to call
-    QOpenGLContext::swapBuffers() yourself afterward.
-
-    The framebuffer specified by \a fboId will be bound automatically.
-
-    \sa QOpenGLContext::swapBuffers(), QOpenGLFramebufferObject::handle()
+    Renders the scene.
  */
 
 /*!
diff --git a/src/quick/scenegraph/coreapi/qsgabstractrenderer_p.h b/src/quick/scenegraph/coreapi/qsgabstractrenderer_p.h
index 5d48f18310..83084cbd0f 100644
--- a/src/quick/scenegraph/coreapi/qsgabstractrenderer_p.h
+++ b/src/quick/scenegraph/coreapi/qsgabstractrenderer_p.h
@@ -107,7 +107,7 @@ public:
     void setClearMode(ClearMode mode);
     ClearMode clearMode() const;
 
-    virtual void renderScene(GLuint fboId = 0) = 0;
+    virtual void renderScene() = 0;
 
 Q_SIGNALS:
     void sceneGraphChanged();
diff --git a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
index 5863af85d3..bec693ed99 100644
--- a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
+++ b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
@@ -3488,6 +3488,9 @@ void Renderer::deleteRemovedElements()
 
 void Renderer::render()
 {
+    if (!renderTarget())
+        return;
+
     if (Q_UNLIKELY(debug_dump())) {
         qDebug("\n");
         QSGNodeDumper::dump(rootNode());
diff --git a/src/quick/scenegraph/coreapi/qsgrenderer.cpp b/src/quick/scenegraph/coreapi/qsgrenderer.cpp
index cd16014d41..4a7d2ce31d 100644
--- a/src/quick/scenegraph/coreapi/qsgrenderer.cpp
+++ b/src/quick/scenegraph/coreapi/qsgrenderer.cpp
@@ -39,11 +39,6 @@
 
 #include "qsgrenderer_p.h"
 #include "qsgnodeupdater_p.h"
-#if QT_CONFIG(opengl)
-# include <QOpenGLFramebufferObject>
-# include <QOpenGLContext>
-# include <QOpenGLFunctions>
-#endif
 #include <private/qquickprofiler_p.h>
 #include <qtquick_tracepoints_p.h>
 
@@ -68,38 +63,6 @@ int qt_sg_envInt(const char *name, int defaultValue)
     return ok ? value : defaultValue;
 }
 
-void QSGBindable::clear(QSGAbstractRenderer::ClearMode mode) const
-{
-#if QT_CONFIG(opengl)
-    GLuint bits = 0;
-    if (mode & QSGAbstractRenderer::ClearColorBuffer) bits |= GL_COLOR_BUFFER_BIT;
-    if (mode & QSGAbstractRenderer::ClearDepthBuffer) bits |= GL_DEPTH_BUFFER_BIT;
-    if (mode & QSGAbstractRenderer::ClearStencilBuffer) bits |= GL_STENCIL_BUFFER_BIT;
-    QOpenGLContext::currentContext()->functions()->glClear(bits);
-#else
-    Q_UNUSED(mode)
-#endif
-}
-
-// Reactivate the color buffer after switching to the stencil.
-void QSGBindable::reactivate() const
-{
-#if QT_CONFIG(opengl)
-    QOpenGLContext::currentContext()->functions()->glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
-#endif
-}
-#if QT_CONFIG(opengl)
-QSGBindableFboId::QSGBindableFboId(GLuint id)
-    : m_id(id)
-{
-}
-
-
-void QSGBindableFboId::bind() const
-{
-    QOpenGLContext::currentContext()->functions()->glBindFramebuffer(GL_FRAMEBUFFER, m_id);
-}
-#endif
 /*!
     \class QSGRenderer
     \brief The renderer class is the abstract baseclass used for rendering the
@@ -140,7 +103,6 @@ QSGRenderer::QSGRenderer(QSGRenderContext *context)
     , m_cb(nullptr)
     , m_rp_desc(nullptr)
     , m_node_updater(nullptr)
-    , m_bindable(nullptr)
     , m_changed_emitted(false)
     , m_is_rendering(false)
     , m_is_preprocessing(false)
@@ -189,35 +151,7 @@ bool QSGRenderer::isMirrored() const
     return matrix(0, 0) * matrix(1, 1) - matrix(0, 1) * matrix(1, 0) > 0;
 }
 
-void QSGRenderer::renderScene(uint fboId)
-{
-    if (m_rt) {
-        class B : public QSGBindable
-        {
-        public:
-            void bind() const override { }
-        } bindable;
-        renderScene(bindable);
-    } else {
-#if QT_CONFIG(opengl)
-        if (fboId) {
-            QSGBindableFboId bindable(fboId);
-            renderScene(bindable);
-        } else {
-            class B : public QSGBindable
-            {
-            public:
-                void bind() const override { QOpenGLFramebufferObject::bindDefault(); }
-            } bindable;
-            renderScene(bindable);
-        }
-#else
-        Q_UNUSED(fboId)
-#endif
-    }
-}
-
-void QSGRenderer::renderScene(const QSGBindable &bindable)
+void QSGRenderer::renderScene()
 {
     if (!rootNode())
         return;
@@ -225,42 +159,16 @@ void QSGRenderer::renderScene(const QSGBindable &bindable)
     Q_TRACE_SCOPE(QSG_renderScene);
     m_is_rendering = true;
 
-
     bool profileFrames = QSG_LOG_TIME_RENDERER().isDebugEnabled();
     if (profileFrames)
         frameTimer.start();
     Q_QUICK_SG_PROFILE_START(QQuickProfiler::SceneGraphRendererFrame);
 
-    qint64 bindTime = 0;
     qint64 renderTime = 0;
 
-    m_bindable = &bindable;
     preprocess();
 
-    Q_TRACE(QSG_binding_entry);
-    bindable.bind();
-    if (profileFrames)
-        bindTime = frameTimer.nsecsElapsed();
-    Q_TRACE(QSG_binding_exit);
-    Q_QUICK_SG_PROFILE_RECORD(QQuickProfiler::SceneGraphRendererFrame,
-                              QQuickProfiler::SceneGraphRendererBinding);
     Q_TRACE(QSG_render_entry);
-
-#if QT_CONFIG(opengl)
-    // Sanity check that attribute registers are disabled
-    if (qsg_sanity_check) {
-        GLint count = 0;
-        QOpenGLContext::currentContext()->functions()->glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &count);
-        GLint enabled;
-        for (int i=0; i<count; ++i) {
-            QOpenGLContext::currentContext()->functions()->glGetVertexAttribiv(i, GL_VERTEX_ATTRIB_ARRAY_ENABLED, &enabled);
-            if (enabled) {
-                qWarning("QSGRenderer: attribute %d is enabled, this can lead to memory corruption and crashes.", i);
-            }
-        }
-    }
-#endif
-
     render();
     if (profileFrames)
         renderTime = frameTimer.nsecsElapsed();
@@ -270,15 +178,13 @@ void QSGRenderer::renderScene(const QSGBindable &bindable)
 
     m_is_rendering = false;
     m_changed_emitted = false;
-    m_bindable = nullptr;
 
     qCDebug(QSG_LOG_TIME_RENDERER,
-            "time in renderer: total=%dms, preprocess=%d, updates=%d, binding=%d, rendering=%d",
+            "time in renderer: total=%dms, preprocess=%d, updates=%d, rendering=%d",
             int(renderTime / 1000000),
             int(preprocessTime / 1000000),
             int((updatePassTime - preprocessTime) / 1000000),
-            int((bindTime - updatePassTime) / 1000000),
-            int((renderTime - bindTime) / 1000000));
+            int((renderTime - updatePassTime) / 1000000));
 }
 
 /*!
diff --git a/src/quick/scenegraph/coreapi/qsgrenderer_p.h b/src/quick/scenegraph/coreapi/qsgrenderer_p.h
index f9d7d3a65a..08a8325dbb 100644
--- a/src/quick/scenegraph/coreapi/qsgrenderer_p.h
+++ b/src/quick/scenegraph/coreapi/qsgrenderer_p.h
@@ -59,7 +59,6 @@
 
 QT_BEGIN_NAMESPACE
 
-class QSGBindable;
 class QSGNodeUpdater;
 class QRhiRenderTarget;
 class QRhiCommandBuffer;
@@ -87,8 +86,7 @@ public:
     QSGRenderContext *context() const { return m_context; }
 
     bool isMirrored() const;
-    void renderScene(const QSGBindable &bindable);
-    void renderScene(uint fboId = 0) override;
+    void renderScene() override;
     void nodeChanged(QSGNode *node, QSGNode::DirtyState state) override;
 
     QSGNodeUpdater *nodeUpdater() const;
@@ -127,8 +125,6 @@ public:
 protected:
     virtual void render() = 0;
 
-    const QSGBindable *bindable() const { return m_bindable; }
-
     virtual void preprocess();
 
     void addNodesToPreprocess(QSGNode *node);
@@ -161,33 +157,11 @@ private:
     QSet<QSGNode *> m_nodes_to_preprocess;
     QSet<QSGNode *> m_nodes_dont_preprocess;
 
-    const QSGBindable *m_bindable;
-
     uint m_changed_emitted : 1;
     uint m_is_rendering : 1;
     uint m_is_preprocessing : 1;
 };
 
-class Q_QUICK_PRIVATE_EXPORT QSGBindable
-{
-public:
-    virtual ~QSGBindable() { }
-    virtual void bind() const = 0;
-    virtual void clear(QSGAbstractRenderer::ClearMode mode) const;
-    virtual void reactivate() const;
-};
-#if QT_CONFIG(opengl)
-class QSGBindableFboId : public QSGBindable
-{
-public:
-    QSGBindableFboId(GLuint);
-    void bind() const override;
-private:
-    GLuint m_id;
-};
-#endif
-
-
 QSGMaterialShader::RenderState QSGRenderer::state(QSGMaterialShader::RenderState::DirtyStates dirty) const
 {
     QSGMaterialShader::RenderState s;
diff --git a/src/quick/scenegraph/qsgcontext_p.h b/src/quick/scenegraph/qsgcontext_p.h
index a2cb21a60c..1696ee9cba 100644
--- a/src/quick/scenegraph/qsgcontext_p.h
+++ b/src/quick/scenegraph/qsgcontext_p.h
@@ -178,7 +178,7 @@ public:
                                 RenderPassCallback mainPassRecordingStart,
                                 RenderPassCallback mainPassRecordingEnd,
                                 void *callbackUserData);
-    virtual void renderNextFrame(QSGRenderer *renderer, uint fboId) = 0;
+    virtual void renderNextFrame(QSGRenderer *renderer) = 0;
     virtual void endNextFrame(QSGRenderer *renderer);
 
     virtual void beginNextRhiFrame(QSGRenderer *renderer,
diff --git a/src/quick/scenegraph/qsgdefaultcontext.cpp b/src/quick/scenegraph/qsgdefaultcontext.cpp
index 5204c3ecfc..fee1a8449e 100644
--- a/src/quick/scenegraph/qsgdefaultcontext.cpp
+++ b/src/quick/scenegraph/qsgdefaultcontext.cpp
@@ -57,7 +57,6 @@
 #include <QtQuick/private/qsgrhishadereffectnode_p.h>
 
 #include <QOpenGLContext>
-#include <QOpenGLFramebufferObject>
 
 #include <QtQuick/private/qquickwindow_p.h>
 #include <QtQuick/private/qquickitem_p.h>
diff --git a/src/quick/scenegraph/qsgdefaultrendercontext.cpp b/src/quick/scenegraph/qsgdefaultrendercontext.cpp
index be110b5de5..0214b1b94c 100644
--- a/src/quick/scenegraph/qsgdefaultrendercontext.cpp
+++ b/src/quick/scenegraph/qsgdefaultrendercontext.cpp
@@ -231,12 +231,12 @@ void QSGDefaultRenderContext::beginNextFrame(QSGRenderer *renderer,
     renderer->setRenderPassRecordingCallbacks(mainPassRecordingStart, mainPassRecordingEnd, callbackUserData);
 }
 
-void QSGDefaultRenderContext::renderNextFrame(QSGRenderer *renderer, uint fboId)
+void QSGDefaultRenderContext::renderNextFrame(QSGRenderer *renderer)
 {
     if (m_serializedRender)
         qsg_framerender_mutex.lock();
 
-    renderer->renderScene(fboId);
+    renderer->renderScene();
 
     if (m_serializedRender)
         qsg_framerender_mutex.unlock();
diff --git a/src/quick/scenegraph/qsgdefaultrendercontext_p.h b/src/quick/scenegraph/qsgdefaultrendercontext_p.h
index b6ed57ba6a..a2d3a1b20c 100644
--- a/src/quick/scenegraph/qsgdefaultrendercontext_p.h
+++ b/src/quick/scenegraph/qsgdefaultrendercontext_p.h
@@ -109,7 +109,7 @@ public:
                         RenderPassCallback mainPassRecordingStart,
                         RenderPassCallback mainPassRecordingEnd,
                         void *callbackUserData) override;
-    void renderNextFrame(QSGRenderer *renderer, uint fboId) override;
+    void renderNextFrame(QSGRenderer *renderer) override;
     void endNextFrame(QSGRenderer *renderer) override;
 
     void beginNextRhiFrame(QSGRenderer *renderer,