QQuickWindow: fix resetOpenGLState handling of vertex arrays

In the core profile it's forbidden to set vertex attributes
(via glVertexAttribPointer and similar) when there's no VAO bound.
Similarly, if there's a VAO bound when calling resetOpenGLState,
then we need to unbind it or those operations will affect its status.

Change-Id: Id7db028ddde9f9429f5a210b8b3d1468888dbce4
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

2 files changed, 26 insertions, 6 deletions

diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index f57d04dfad..0233e93443 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -74,6 +74,8 @@
 #include <private/qqmlprofilerservice_p.h>
 #include <private/qqmlmemoryprofiler_p.h>
 
+#include <private/qopenglvertexarrayobject_p.h>
+
 QT_BEGIN_NAMESPACE
 
 Q_LOGGING_CATEGORY(DBG_TOUCH, "qt.quick.touch");
@@ -415,6 +417,7 @@ QQuickWindowPrivate::QQuickWindowPrivate()
     , lastFocusReason(Qt::OtherFocusReason)
     , renderTarget(0)
     , renderTargetId(0)
+    , vaoHelper(0)
     , incubationController(0)
 {
 #ifndef QT_NO_DRAGANDDROP
@@ -2832,6 +2835,9 @@ void QQuickWindow::cleanupSceneGraph()
 {
     Q_D(QQuickWindow);
 
+    delete d->vaoHelper;
+    d->vaoHelper = 0;
+
     if (!d->renderer)
         return;
 
@@ -3517,16 +3523,26 @@ void QQuickWindow::resetOpenGLState()
     if (!openglContext())
         return;
 
-    QOpenGLFunctions *gl = openglContext()->functions();
+    Q_D(QQuickWindow);
+
+    QOpenGLContext *ctx = openglContext();
+    QOpenGLFunctions *gl = ctx->functions();
 
     gl->glBindBuffer(GL_ARRAY_BUFFER, 0);
     gl->glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
 
-    int maxAttribs;
-    gl->glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &maxAttribs);
-    for (int i=0; i<maxAttribs; ++i) {
-        gl->glVertexAttribPointer(i, 4, GL_FLOAT, GL_FALSE, 0, 0);
-        gl->glDisableVertexAttribArray(i);
+    if (!d->vaoHelper)
+        d->vaoHelper = new QOpenGLVertexArrayObjectHelper(ctx);
+    if (d->vaoHelper->isValid())
+        d->vaoHelper->glBindVertexArray(0);
+
+    if (ctx->isOpenGLES() || (gl->openGLFeatures() & QOpenGLFunctions::FixedFunctionPipeline)) {
+        int maxAttribs;
+        gl->glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &maxAttribs);
+        for (int i=0; i<maxAttribs; ++i) {
+            gl->glVertexAttribPointer(i, 4, GL_FLOAT, GL_FALSE, 0, 0);
+            gl->glDisableVertexAttribArray(i);
+        }
     }
 
     gl->glActiveTexture(GL_TEXTURE0);
diff --git a/src/quick/items/qquickwindow_p.h b/src/quick/items/qquickwindow_p.h
index 66202aec5c..8f0696914e 100644
--- a/src/quick/items/qquickwindow_p.h
+++ b/src/quick/items/qquickwindow_p.h
@@ -94,6 +94,8 @@ class QTouchEvent;
 class QQuickWindowRenderLoop;
 class QQuickWindowIncubationController;
 
+class QOpenGLVertexArrayObjectHelper;
+
 class Q_QUICK_PRIVATE_EXPORT QQuickWindowPrivate : public QWindowPrivate
 {
 public:
@@ -233,6 +235,8 @@ public:
     uint renderTargetId;
     QSize renderTargetSize;
 
+    QOpenGLVertexArrayObjectHelper *vaoHelper;
+
     // Keeps track of which touch point (int) was last accepted by which item
     QHash<int, QQuickItem *> itemForTouchPointId;