Apart from GLSL, we also need to have the usual Python code that initializes the window, loads shaders, and so on. The following program will serve as a good starting point:
from kivy.app import App
from kivy.base import EventLoop
from kivy.graphics import Mesh
from kivy.graphics.instructions import RenderContext
from kivy.uix.widget import Widget
class GlslDemo(Widget):
def __init__(self, **kwargs):
Widget.__init__(self, **kwargs)
self.canvas = RenderContext(use_parent_projection=True)
self.canvas.shader.source = 'basic.glsl'
# Set up geometry here.
class GlslApp(App):
def build(self):
EventLoop.ensure_window()
return GlslDemo()
if __name__ == '__main__':
GlslApp().run()We created just one widget named GlslDemo in this example; it will host all the rendering. RenderContext is a customizable Canvas subclass that allows us to replace shaders easily, as shown in the listing. The basic.glsl file contains...