Add support for OpenGL 3.2+ core profile contexts in QPainter

This change allows painting via QPainter onto a QOpenGLWindow, QOpenGLWidget
or QOpenGLFramebufferObject when an core profile context is in use. This is
important on macOS in particular, where compatibility profiles are not
available, and so the only way to use modern OpenGL is via a core profile
context.

Added core profile compatible shaders with moder GLSL keywords.

The paint engine binds a VAO and two VBOs from now on, whenever VAOs are
supported. Note that this changes behavior also for OpenGL 2.x context that
have VAO support via extensions.

The Lancelot test suite gains support for core profile contexts. This can
be triggered via -coreglbuffer in place of -glbuffer when manually inspecting
via 'lance', while tst_lancelot will automatically run core context-based tests
whenever supported.

Task-number: QTBUG-33535
Change-Id: I6323a7ea2aaa9e111651ebbffd3e40259c8e7a9c
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

2 files changed, 52 insertions, 3 deletions

diff --git a/tests/auto/other/lancelot/paintcommands.cpp b/tests/auto/other/lancelot/paintcommands.cpp
index 2e6cb09aa5..971b9b5fe7 100644
--- a/tests/auto/other/lancelot/paintcommands.cpp
+++ b/tests/auto/other/lancelot/paintcommands.cpp
@@ -2378,6 +2378,8 @@ void PaintCommands::command_surface_begin(QRegExp re)
 #ifndef QT_NO_OPENGL
         m_default_glcontext = QOpenGLContext::currentContext();
         m_surface_glcontext = new QOpenGLContext();
+        // Pick up the format from the current context; this is especially
+        // important in order to pick the right version/profile to test.
         m_surface_glcontext->setFormat(m_default_glcontext->format());
         m_surface_glcontext->create();
         m_surface_glcontext->makeCurrent(m_default_glcontext->surface());
diff --git a/tests/auto/other/lancelot/tst_lancelot.cpp b/tests/auto/other/lancelot/tst_lancelot.cpp
index 972e5ca967..63c62bab86 100644
--- a/tests/auto/other/lancelot/tst_lancelot.cpp
+++ b/tests/auto/other/lancelot/tst_lancelot.cpp
@@ -53,7 +53,7 @@ private:
     };
 
     void setupTestSuite(const QStringList& blacklist = QStringList());
-    void runTestSuite(GraphicsEngine engine, QImage::Format format);
+    void runTestSuite(GraphicsEngine engine, QImage::Format format, const QSurfaceFormat &contextFormat = QSurfaceFormat());
     void paint(QPaintDevice *device, GraphicsEngine engine, const QStringList &script, const QString &filePath);
 
     QStringList qpsFiles;
@@ -85,8 +85,11 @@ private slots:
 #ifndef QT_NO_OPENGL
     void testOpenGL_data();
     void testOpenGL();
+    void testCoreOpenGL_data();
+    void testCoreOpenGL();
 private:
     bool checkSystemGLSupport();
+    bool checkSystemCoreGLSupport();
 #endif
 };
 
@@ -236,6 +239,32 @@ bool tst_Lancelot::checkSystemGLSupport()
     return true;
 }
 
+bool tst_Lancelot::checkSystemCoreGLSupport()
+{
+    if (QOpenGLContext::openGLModuleType() != QOpenGLContext::LibGL)
+        return false;
+
+    QSurfaceFormat coreFormat;
+    coreFormat.setVersion(3, 2);
+    coreFormat.setProfile(QSurfaceFormat::CoreProfile);
+    QWindow win;
+    win.setSurfaceType(QSurface::OpenGLSurface);
+    win.setFormat(coreFormat);
+    win.create();
+    QOpenGLFramebufferObjectFormat fmt;
+    fmt.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
+    fmt.setSamples(4);
+    QOpenGLContext ctx;
+    ctx.setFormat(coreFormat);
+    if (!ctx.create() || !ctx.makeCurrent(&win))
+        return false;
+    QOpenGLFramebufferObject fbo(800, 800, fmt);
+    if (!fbo.isValid() || !fbo.bind())
+        return false;
+
+    return true;
+}
+
 void tst_Lancelot::testOpenGL_data()
 {
     if (!checkSystemGLSupport())
@@ -249,6 +278,22 @@ void tst_Lancelot::testOpenGL()
 {
     runTestSuite(OpenGL, QImage::Format_RGB32);
 }
+
+void tst_Lancelot::testCoreOpenGL_data()
+{
+    if (!checkSystemCoreGLSupport())
+        QSKIP("System under test does not meet preconditions for Core Profile GL testing. Skipping.");
+    QStringList localBlacklist = QStringList() << QLatin1String("rasterops.qps");
+    setupTestSuite(localBlacklist);
+}
+
+void tst_Lancelot::testCoreOpenGL()
+{
+    QSurfaceFormat coreFormat;
+    coreFormat.setVersion(3, 2);
+    coreFormat.setProfile(QSurfaceFormat::CoreProfile);
+    runTestSuite(OpenGL, QImage::Format_RGB32, coreFormat);
+}
 #endif
 
 
@@ -263,7 +308,7 @@ void tst_Lancelot::setupTestSuite(const QStringList& blacklist)
 }
 
 
-void tst_Lancelot::runTestSuite(GraphicsEngine engine, QImage::Format format)
+void tst_Lancelot::runTestSuite(GraphicsEngine engine, QImage::Format format, const QSurfaceFormat &contextFormat)
 {
     QFETCH(QString, qpsFile);
 
@@ -279,11 +324,13 @@ void tst_Lancelot::runTestSuite(GraphicsEngine engine, QImage::Format format)
     } else if (engine == OpenGL) {
         QWindow win;
         win.setSurfaceType(QSurface::OpenGLSurface);
+        win.setFormat(contextFormat);
         win.create();
         QOpenGLFramebufferObjectFormat fmt;
         fmt.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
         fmt.setSamples(4);
         QOpenGLContext ctx;
+        ctx.setFormat(contextFormat);
         QVERIFY(ctx.create());
         QVERIFY(ctx.makeCurrent(&win));
         QOpenGLFramebufferObject fbo(800, 800, fmt);
@@ -304,7 +351,7 @@ void tst_Lancelot::paint(QPaintDevice *device, GraphicsEngine engine, const QStr
     //pcmd.setShouldDrawText(false);
     switch (engine) {
     case OpenGL:
-        pcmd.setType(OpenGLBufferType);
+        pcmd.setType(OpenGLBufferType); // version/profile is communicated through the context's format()
         break;
     case Raster:  // fallthrough
     default: