Table Of Contents
Framebuffer¶
Fbo is like an offscreen window. You can activate the fbo for rendering into a texture, and use your fbo as a texture for another drawing.
Fbo act as a kivy.graphics.instructions.Canvas.
Example of using an fbo for some color rectangles:
from kivy.graphics import Fbo, Color, Rectangle
class FboTest(Widget):
def __init__(self, **kwargs):
super(FboTest, self).__init__(**kwargs)
# first step is to create the fbo and use the fbo texture on other
# rectangle
with self.canvas:
# create the fbo
self.fbo = Fbo(size=(256, 256))
# show our fbo on the widget in different size
Color(1, 1, 1)
Rectangle(size=(32, 32), texture=self.fbo.texture)
Rectangle(pos=(32, 0), size=(64, 64), texture=self.fbo.texture)
Rectangle(pos=(96, 0), size=(128, 128), texture=self.fbo.texture)
# in the second step, you can draw whatever you want on the fbo
with self.fbo:
Color(1, 0, 0, .8)
Rectangle(size=(256, 64))
Color(0, 1, 0, .8)
Rectangle(size=(64, 256))
If you change anything in the self.fbo object, it will be automaticly updated, and canvas where the fbo is putted will be automaticly updated too.
Reloading the FBO content¶
New in version 1.2.0.
If the OpenGL context is lost, then the FBO is lost too. You need to reupload data on it yourself. Use the Fbo.add_reload_observer() to add a reloading function that will be automatically called when needed:
def __init__(self, **kwargs):
super(...).__init__(**kwargs)
self.fbo = Fbo(size=(512, 512))
self.fbo.add_reload_observer(self.populate_fbo)
# and load the data now.
self.populate_fbo(self.fbo)
def populate_fbo(self, fbo):
with fbo:
# .. put your Color / Rectangle / ... here
This way, you could use the same method for initialization and for reloading. But it’s up to you.
- class kivy.graphics.fbo.Fbo¶
Bases: kivy.graphics.instructions.RenderContext
Fbo class for wrapping the OpenGL Framebuffer extension. The Fbo support “with” statement.
Parameters : - clear_color: tuple, default to (0, 0, 0, 0)
Define the default color for clearing the framebuffer
- size: tuple, default to (1024, 1024)
Default size of the framebuffer
- push_viewport: bool, default to True
If True, the OpenGL viewport will be set to the framebuffer size, and will be automatically restored when the framebuffer released.
- with_depthbuffer: bool, default to False
If True, the framebuffer will be allocated with a Z buffer.
- texture: Texture, default to None
If None, a default texture will be created.
- add_reload_observer()¶
Add a callback to be called after the whole graphics context have been reloaded. This is where you can reupload your custom data in GPU.
New in version 1.2.0.
Parameters : - callback: func(context) -> return None
The first parameter will be the context itself
- bind()¶
Bind the FBO to the current opengl context. Bind mean that you enable the Framebuffer, and all the drawing operations will act inside the Framebuffer, until release() is called.
The bind/release operation are automatically done when you add graphics object in it. But if you want to manipulate a Framebuffer yourself, you can use it like this:
self.fbo = FBO() self.fbo.bind() # do any drawing command self.fbo.release() # then, your fbo texture is available at print self.fbo.texture
- clear_buffer()¶
Clear the framebuffer with the clear_color.
You need to bound the framebuffer yourself before calling this method:
fbo.bind() fbo.clear_buffer() fbo.release()
- clear_color¶
Clear color in (red, green, blue, alpha) format.
- pixels¶
Get the pixels texture, in RGBA format only, unsigned byte.
New in version 1.7.0.
- release()¶
Release the Framebuffer (unbind).
- remove_reload_observer()¶
Remove a callback from the observer list, previously added by add_reload_observer().
New in version 1.2.0.
- size¶
Size of the framebuffer, in (width, height) format.
If you change the size, the framebuffer content will be lost.
- texture¶
Return the framebuffer texture