From 508db17de38b2940d95742319abcb84ee4ca8b86 Mon Sep 17 00:00:00 2001 From: Gunnar Sletta Date: Tue, 11 Dec 2012 16:58:14 +0100 Subject: Some fixes to the OpenGL docs in GUI Change-Id: I6415ff16b1765a5814d50a4cd39db00495d43073 Reviewed-by: Paul Olav Tvete --- src/gui/opengl/qopenglpaintdevice.cpp | 44 +++++++++++++++++++++++++++++++---- 1 file changed, 40 insertions(+), 4 deletions(-) (limited to 'src/gui/opengl/qopenglpaintdevice.cpp') diff --git a/src/gui/opengl/qopenglpaintdevice.cpp b/src/gui/opengl/qopenglpaintdevice.cpp index b2ffac69ca..79e692b8cf 100644 --- a/src/gui/opengl/qopenglpaintdevice.cpp +++ b/src/gui/opengl/qopenglpaintdevice.cpp @@ -63,11 +63,47 @@ QT_BEGIN_NAMESPACE \ingroup painting-3D + The QOpenGLPaintDevice uses the current QOpenGL context to render + QPainter draw commands. It requires OpenGL (ES) 2.0 support or + higher. + + \section1 Performance + + The QOpenGLPaintDevice is almost always hardware accelerated and + has the potential of being much faster than software + rasterization. However, it is more sensitive to state changes, and + therefore requires the drawing commands to be carefully ordered to + achieve optimal performance. + + \section1 Antialiasing and Quality + + Antialiasing in the OpenGL paint engine is done using + multisampling. Most hardware require significantly more memory to + do multisampling and the resulting quality is not on par with the + quality of the software paint engine. The OpenGL paint engine's + strenght lies in its performance, not its visual rendering + quality. + + \section1 State Changes + When painting to a QOpenGLPaintDevice using QPainter, the state of - the current OpenGL context will be altered by the paint engine to reflect - its needs. Applications should not rely upon the OpenGL state being reset - to its original conditions, particularly the current shader program, - OpenGL viewport, texture units, and drawing modes. + the current OpenGL context will be altered by the paint engine to + reflect its needs. Applications should not rely upon the OpenGL + state being reset to its original conditions, particularly the + current shader program, OpenGL viewport, texture units, and + drawing modes. + + \section1 Mixing QPainter and OpenGL + + When intermixing QPainter and OpenGL, it is important to notify + QPainter that the OpenGL state may have been cluttered so it can + restore its internal state. This is acheived by calling \l + QPainter::beginNativePainting() before starting the OpenGL + rendering and calling \l QPainter::endNativePainting() after + finishing. + + \sa {OpenGL Window Example} + */ class QOpenGLPaintDevicePrivate -- cgit v1.2.3