QGLFramebufferObject¶

Synopsis¶

Functions¶

def attachment ()
def bind ()
def drawTexture (point, textureId[, textureTarget=0x0DE1])
def drawTexture (target, textureId[, textureTarget=0x0DE1])
def format ()
def handle ()
def isBound ()
def isValid ()
def release ()
def size ()
def texture ()
def toImage ()

Static functions¶

def bindDefault ()
def blitFramebuffer (target, targetRect, source, sourceRect[, buffers=0x00004000[, filter=0x2600]])
def hasOpenGLFramebufferBlit ()
def hasOpenGLFramebufferObjects ()

Detailed Description¶

The PySide.QtOpenGL.QGLFramebufferObject class encapsulates an OpenGL framebuffer object.

The PySide.QtOpenGL.QGLFramebufferObject class encapsulates an OpenGL framebuffer object, defined by the GL_EXT_framebuffer_object extension. In addition it provides a rendering surface that can be painted on with a PySide.QtGui.QPainter , rendered to using native GL calls, or both. This surface can be bound and used as a regular texture in your own GL drawing code. By default, the PySide.QtOpenGL.QGLFramebufferObject class generates a 2D GL texture (using the GL_TEXTURE_2D target), which is used as the internal rendering target.

It is important to have a current GL context when creating a :class:`PySide.QtOpenGL.QGLFramebufferObject` **, otherwise initialization will fail.

OpenGL framebuffer objects and pbuffers (see PySide.QtOpenGL.QGLPixelBuffer ) can both be used to render to offscreen surfaces, but there are a number of advantages with using framebuffer objects instead of pbuffers:

When using a PySide.QtGui.QPainter to paint to a PySide.QtOpenGL.QGLFramebufferObject you should take care that the PySide.QtOpenGL.QGLFramebufferObject is created with the CombinedDepthStencil attachment for PySide.QtGui.QPainter to be able to render correctly. Note that you need to create a PySide.QtOpenGL.QGLFramebufferObject with more than one sample per pixel for primitives to be antialiased when drawing using a PySide.QtGui.QPainter . To create a multisample framebuffer object you should use one of the constructors that take a PySide.QtOpenGL.QGLFramebufferObject parameter, and set the QGLFramebufferObject::samples() property to a non-zero value.

When painting to a PySide.QtOpenGL.QGLFramebufferObject using PySide.QtGui.QPainter , the state of the current GL context will be altered by the paint engine to reflect its needs. Applications should not rely upon the GL state being reset to its original conditions, particularly the current shader program, GL viewport, texture units, and drawing modes.

For multisample framebuffer objects a color render buffer is created, otherwise a texture with the specified texture target is created. The color render buffer or texture will have the specified internal format, and will be bound to the GL_COLOR_ATTACHMENT0 attachment in the framebuffer object.

If you want to use a framebuffer object with multisampling enabled as a texture, you first need to copy from it to a regular framebuffer object using QGLContext::blitFramebuffer().

Threading¶

As of Qt 4.8, it’s possible to draw into a PySide.QtOpenGL.QGLFramebufferObject using a PySide.QtGui.QPainter in a separate thread. Note that OpenGL 2.0 or OpenGL ES 2.0 is required for this to work. Also, under X11, it’s necessary to set the Qt.AA_X11InitThreads application attribute.

See also

Framebuffer Object Example

class PySide.QtOpenGL.QGLFramebufferObject(size[, target=0x0DE1])¶

class PySide.QtOpenGL.QGLFramebufferObject(size, attachment[, target=0x0DE1[, internal_format=0x8058]])

class PySide.QtOpenGL.QGLFramebufferObject(size, format)

class PySide.QtOpenGL.QGLFramebufferObject(width, height[, target=0x0DE1])

class PySide.QtOpenGL.QGLFramebufferObject(width, height, attachment[, target=0x0DE1[, internal_format=0x8058]])

class PySide.QtOpenGL.QGLFramebufferObject(width, height, format)

Parameters:	width – `PySide.QtCore.int` target – `PySide.QtOpenGL.GLenum` size – `PySide.QtCore.QSize` format – `PySide.QtOpenGL.QGLFramebufferObjectFormat` height – `PySide.QtCore.int` internal_format – `PySide.QtOpenGL.GLenum` attachment – `PySide.QtOpenGL.QGLFramebufferObject.Attachment`

Constructs an OpenGL framebuffer object and binds a 2D GL texture to the buffer of the size size . The texture is bound to the GL_COLOR_ATTACHMENT0 target in the framebuffer object.

The target parameter is used to specify the GL texture target. The default target is GL_TEXTURE_2D . Keep in mind that GL_TEXTURE_2D textures must have a power of 2 width and height (e.g. 256x512), unless you are using OpenGL 2.0 or higher.

By default, no depth and stencil buffers are attached. This behavior can be toggled using one of the overloaded constructors.

The default internal texture format is GL_RGBA8 for desktop OpenGL, and GL_RGBA for OpenGL/ES.

It is important that you have a current GL context set when creating the PySide.QtOpenGL.QGLFramebufferObject , otherwise the initialization will fail.