1 files changed, 63 insertions, 6 deletions

diff --git a/src/gui/opengl/qopenglbuffer.cpp b/src/gui/opengl/qopenglbuffer.cpp
index a8a2255104..3ae45abb11 100644
--- a/src/gui/opengl/qopenglbuffer.cpp
+++ b/src/gui/opengl/qopenglbuffer.cpp
@@ -128,6 +128,18 @@ QT_BEGIN_NAMESPACE
     \value ReadWrite The buffer will be mapped for reading and writing.
 */
 
+/*!
+    \enum QOpenGLBuffer::RangeAccessFlag
+    This enum defines the access mode bits for QOpenGLBuffer::mapRange().
+
+    \value RangeRead The buffer will be mapped for reading.
+    \value RangeWrite The buffer will be mapped for writing.
+    \value RangeInvalidate Discard the previous contents of the specified range.
+    \value RangeInvalidateBuffer Discard the previous contents of the entire buffer.
+    \value RangeFlushExplicit Indicates that modifications are to be flushed explicitly via \c glFlushMappedBufferRange.
+    \value RangeUnsynchronized Indicates that pending operations should not be synchronized before returning from mapRange().
+*/
+
 class QOpenGLBufferPrivate
 {
 public:
@@ -514,10 +526,14 @@ int QOpenGLBuffer::size() const
     It is assumed that create() has been called on this buffer and that
     it has been bound to the current context.
 
-    This function is only supported under OpenGL/ES if the
-    \c{GL_OES_mapbuffer} extension is present.
+    \note This function is only supported under OpenGL ES 2.0 or
+    earlier if the \c GL_OES_mapbuffer extension is present.
 
-    \sa unmap(), create(), bind()
+    \note On OpenGL ES 3.0 and newer, or, in case if desktop OpenGL,
+    if \c GL_ARB_map_buffer_range is supported, this function uses
+    \c glMapBufferRange instead of \c glMapBuffer.
+
+    \sa unmap(), create(), bind(), mapRange()
 */
 void *QOpenGLBuffer::map(QOpenGLBuffer::Access access)
 {
@@ -528,7 +544,48 @@ void *QOpenGLBuffer::map(QOpenGLBuffer::Access access)
 #endif
     if (!d->guard || !d->guard->id())
         return 0;
-    return d->funcs->glMapBuffer(d->type, access);
+    if (d->funcs->hasOpenGLExtension(QOpenGLExtensions::MapBufferRange)) {
+        QOpenGLBuffer::RangeAccessFlags rangeAccess = 0;
+        switch (access) {
+        case QOpenGLBuffer::ReadOnly:
+            rangeAccess = QOpenGLBuffer::RangeRead;
+            break;
+        case QOpenGLBuffer::WriteOnly:
+            rangeAccess = QOpenGLBuffer::RangeWrite;
+            break;
+        case QOpenGLBuffer::ReadWrite:
+            rangeAccess = QOpenGLBuffer::RangeRead | QOpenGLBuffer::RangeWrite;
+            break;
+        }
+        return d->funcs->glMapBufferRange(d->type, 0, size(), rangeAccess);
+    } else {
+        return d->funcs->glMapBuffer(d->type, access);
+    }
+}
+
+/*!
+    Maps the range specified by \a offset and \a count of the contents
+    of this buffer into the application's memory space and returns a
+    pointer to it.  Returns null if memory mapping is not possible.
+    The \a access parameter specifies a combination of access flags.
+
+    It is assumed that create() has been called on this buffer and that
+    it has been bound to the current context.
+
+    \note This function is not available on OpenGL ES 2.0 and earlier.
+
+    \sa unmap(), create(), bind()
+ */
+void *QOpenGLBuffer::mapRange(int offset, int count, QOpenGLBuffer::RangeAccessFlags access)
+{
+    Q_D(QOpenGLBuffer);
+#ifndef QT_NO_DEBUG
+    if (!isCreated())
+        qWarning("QOpenGLBuffer::mapRange(): buffer not created");
+#endif
+    if (!d->guard || !d->guard->id())
+        return 0;
+    return d->funcs->glMapBufferRange(d->type, offset, count, access);
 }
 
 /*!
@@ -539,8 +596,8 @@ void *QOpenGLBuffer::map(QOpenGLBuffer::Access access)
     It is assumed that this buffer has been bound to the current context,
     and that it was previously mapped with map().
 
-    This function is only supported under OpenGL/ES if the
-    \c{GL_OES_mapbuffer} extension is present.
+    \note This function is only supported under OpenGL ES 2.0 and
+    earlier if the \c{GL_OES_mapbuffer} extension is present.
 
     \sa map()
 */