Removed the FBO stacking behaviour and the test attached to it.

Having this behaviour in QGLFrameBufferObject complicates alot of things
and isn't really necessary.

Reviewed-by: Tom Cooksey

3 files changed, 9 insertions, 133 deletions

diff --git a/src/opengl/qglframebufferobject.cpp b/src/opengl/qglframebufferobject.cpp
index 7374594..5295b6d 100644
--- a/src/opengl/qglframebufferobject.cpp
+++ b/src/opengl/qglframebufferobject.cpp
@@ -361,9 +361,6 @@ void QGLFBOGLPaintDevice::beginPaint()
     if (QGLContext::currentContext() != context())
         context()->makeCurrent();
 
-    // We let QFBO track the previously bound FBO rather than doing it
-    // ourselves here. This has the advantage that begin/release & bind/end
-    // work as expected.
     wasBound = fbo->isBound();
     if (!wasBound)
         fbo->bind();
@@ -896,17 +893,11 @@ bool QGLFramebufferObject::bind()
     QGL_FUNC_CONTEXT;
     if (!ctx)
         return false;   // Context no longer exists.
+    const QGLContext *current = QGLContext::currentContext();
     glBindFramebuffer(GL_FRAMEBUFFER_EXT, d->fbo());
     d->valid = d->checkFramebufferStatus();
-    const QGLContext *context = QGLContext::currentContext();
-    if (d->valid && context) {
-        Q_ASSERT(QGLContextPrivate::contextGroup(context) == QGLContextPrivate::contextGroup(ctx));
-        // Save the previous setting to automatically restore in release().
-        if (context->d_ptr->current_fbo != d->fbo()) {
-            d->previous_fbo = context->d_ptr->current_fbo;
-            context->d_ptr->current_fbo = d->fbo();
-        }
-    }
+    if (d->valid && current)
+        current->d_ptr->current_fbo = d->fbo();
     return d->valid;
 }
 
@@ -917,30 +908,20 @@ bool QGLFramebufferObject::bind()
     framebuffer.
     Returns true upon success, false otherwise.
 
-    Since 4.6: if another QGLFramebufferObject instance was already bound
-    to the current context when bind() was called, then this function will
-    automatically re-bind it to the current context.
-
     \sa bind()
 */
 bool QGLFramebufferObject::release()
 {
     if (!isValid())
 	return false;
-    Q_D(QGLFramebufferObject);
     QGL_FUNC_CONTEXT;
     if (!ctx)
         return false;   // Context no longer exists.
 
-    const QGLContext *context = QGLContext::currentContext();
-    if (context) {
-        Q_ASSERT(QGLContextPrivate::contextGroup(context) == QGLContextPrivate::contextGroup(ctx));
-        // Restore the previous setting for stacked framebuffer objects.
-        if (d->previous_fbo != context->d_ptr->current_fbo) {
-            context->d_ptr->current_fbo = d->previous_fbo;
-            glBindFramebuffer(GL_FRAMEBUFFER_EXT, d->previous_fbo);
-        }
-        d->previous_fbo = 0;
+    const QGLContext *current = QGLContext::currentContext();
+    if (current) {
+        current->d_ptr->current_fbo = 0;
+        glBindFramebuffer(GL_FRAMEBUFFER_EXT, 0);
     }
 
     return true;
diff --git a/src/opengl/qglframebufferobject_p.h b/src/opengl/qglframebufferobject_p.h
index 122c42e..c341459 100644
--- a/src/opengl/qglframebufferobject_p.h
+++ b/src/opengl/qglframebufferobject_p.h
@@ -127,7 +127,8 @@ private:
 class QGLFramebufferObjectPrivate
 {
 public:
-    QGLFramebufferObjectPrivate() : fbo_guard(0), texture(0), depth_stencil_buffer(0), color_buffer(0), valid(false), previous_fbo(0), engine(0) {}
+    QGLFramebufferObjectPrivate() : fbo_guard(0), texture(0), depth_stencil_buffer(0)
+                                  , color_buffer(0), valid(false), engine(0) {}
     ~QGLFramebufferObjectPrivate() {}
 
     void init(QGLFramebufferObject *q, const QSize& sz,
@@ -143,7 +144,6 @@ public:
     QGLFramebufferObjectFormat format;
     uint valid : 1;
     QGLFramebufferObject::Attachment fbo_attachment;
-    GLuint previous_fbo;
     mutable QPaintEngine *engine;
     QGLFBOGLPaintDevice glDevice;
 
diff --git a/tests/auto/qgl/tst_qgl.cpp b/tests/auto/qgl/tst_qgl.cpp
index e9f0476..c680dec 100644
--- a/tests/auto/qgl/tst_qgl.cpp
+++ b/tests/auto/qgl/tst_qgl.cpp
@@ -82,7 +82,6 @@ private slots:
     void glPBufferRendering();
     void glWidgetReparent();
     void glWidgetRenderPixmap();
-    void stackedFBOs();
     void colormap();
     void fboFormat();
     void testDontCrashOnDanglingResources();
@@ -1226,110 +1225,6 @@ void tst_QGL::glWidgetRenderPixmap()
     QCOMPARE(fb, reference);
 }
 
-
-// When using multiple FBOs at the same time, unbinding one FBO should re-bind the
-// previous. I.e. It should be possible to have a stack of FBOs where pop'ing there
-// top re-binds the one underneeth.
-void tst_QGL::stackedFBOs()
-{
-    if (!QGLFramebufferObject::hasOpenGLFramebufferObjects())
-        QSKIP("QGLFramebufferObject not supported on this platform", SkipSingle);
-
-    QGLWidget glw;
-    glw.show();
-
-#ifdef Q_WS_X11
-    qt_x11_wait_for_window_manager(&glw);
-#endif
-    QTest::qWait(200);
-
-    glw.makeCurrent();
-
-    // No multisample with combined depth/stencil attachment:
-    QGLFramebufferObjectFormat fboFormat;
-    fboFormat.setAttachment(QGLFramebufferObject::CombinedDepthStencil);
-
-    // Don't complicate things by using NPOT:
-    QGLFramebufferObject *fbo1 = new QGLFramebufferObject(128, 128, fboFormat);
-    QGLFramebufferObject *fbo2 = new QGLFramebufferObject(128, 128, fboFormat);
-    QGLFramebufferObject *fbo3 = new QGLFramebufferObject(128, 128, fboFormat);
-
-    glClearColor(1.0, 0.0, 1.0, 1.0);
-    glClear(GL_COLOR_BUFFER_BIT);
-
-    fbo1->bind();
-        glClearColor(1.0, 0.0, 0.0, 1.0);
-        glClear(GL_COLOR_BUFFER_BIT);
-
-        fbo2->bind();
-            glClearColor(0.0, 1.0, 0.0, 1.0);
-            glClear(GL_COLOR_BUFFER_BIT);
-
-            fbo3->bind();
-                glClearColor(0.0, 0.0, 1.0, 1.0);
-                glClear(GL_COLOR_BUFFER_BIT);
-                glScissor(32, 32, 64, 64);
-                glEnable(GL_SCISSOR_TEST);
-                glClearColor(0.0, 1.0, 1.0, 1.0);
-                glClear(GL_COLOR_BUFFER_BIT);
-            fbo3->release();
-
-            // Scissor rect & test should be left untouched by the fbo release...
-            glClearColor(0.0, 0.0, 0.0, 1.0);
-            glClear(GL_COLOR_BUFFER_BIT);
-        fbo2->release();
-
-        glClearColor(1.0, 1.0, 1.0, 1.0);
-        glClear(GL_COLOR_BUFFER_BIT);
-    fbo1->release();
-
-    glClearColor(1.0, 1.0, 0.0, 1.0);
-    glClear(GL_COLOR_BUFFER_BIT);
-
-    glw.swapBuffers();
-
-    QImage widgetFB = glw.grabFrameBuffer(false).convertToFormat(QImage::Format_RGB32);
-    QImage fb1 = fbo1->toImage().convertToFormat(QImage::Format_RGB32);
-    QImage fb2 = fbo2->toImage().convertToFormat(QImage::Format_RGB32);
-    QImage fb3 = fbo3->toImage().convertToFormat(QImage::Format_RGB32);
-
-    delete fbo1;
-    delete fbo2;
-    delete fbo3;
-
-    QImage widgetReference(widgetFB.size(), widgetFB.format());
-    QImage fb1Reference(fb1.size(), fb1.format());
-    QImage fb2Reference(fb2.size(), fb2.format());
-    QImage fb3Reference(fb3.size(), fb3.format());
-
-    QPainter widgetReferencePainter(&widgetReference);
-    QPainter fb1ReferencePainter(&fb1Reference);
-    QPainter fb2ReferencePainter(&fb2Reference);
-    QPainter fb3ReferencePainter(&fb3Reference);
-
-    widgetReferencePainter.fillRect(0, 0, widgetReference.width(), widgetReference.height(), Qt::magenta);
-    fb1ReferencePainter.fillRect(0, 0, fb1Reference.width(), fb1Reference.height(), Qt::red);
-    fb2ReferencePainter.fillRect(0, 0, fb2Reference.width(), fb2Reference.height(), Qt::green);
-    fb3ReferencePainter.fillRect(0, 0, fb3Reference.width(), fb3Reference.height(), Qt::blue);
-
-    // Flip y-coords to match GL for the widget (which can be any size)
-    widgetReferencePainter.fillRect(32, glw.height() - 96, 64, 64, Qt::yellow);
-    fb1ReferencePainter.fillRect(32, 32, 64, 64, Qt::white);
-    fb2ReferencePainter.fillRect(32, 32, 64, 64, Qt::black);
-    fb3ReferencePainter.fillRect(32, 32, 64, 64, Qt::cyan);
-
-    widgetReferencePainter.end();
-    fb1ReferencePainter.end();
-    fb2ReferencePainter.end();
-    fb3ReferencePainter.end();
-
-    QCOMPARE(widgetFB, widgetReference);
-    QCOMPARE(fb1, fb1Reference);
-    QCOMPARE(fb2, fb2Reference);
-    QCOMPARE(fb3, fb3Reference);
-}
-
-
 class ColormapExtended : public QGLColormap
 {
 public: