Meet a problem about tex_coords on atlas.

[xinming]

Hi, I tried to learn 'tex_coords' according this article (https://blog.kivy.org/2014/02/using-tex_coords-in-kivy-for-fun-and-profit/), I have some try, but sadly, it does not work. here is my code. I want my background moving, but now two problems, one is the texture is the whole altas png, why? two is the  texture.wrap = 'repeat' does not work, why? Hope someone kind have time to help me. Thanks in advance.

from kivy.app import App

from kivy.uix.widget import Widget

from kivy.uix.relativelayout import RelativeLayout

from kivy.lang import Builder

from kivy.atlas import Atlas

from kivy.graphics import Rectangle

from kivy.core.image import Image as CoreImage

from kivy.properties import StringProperty

from kivy.clock import Clock

Builder.load_string('''

<MyLayout>:

    Background:

        img:'atlas://img/background'

''')

class MyLayout(RelativeLayout):

    pass

class Background(Widget):

    img = StringProperty('')

    def __init__(self, **kwargs):

        super(Background, self).__init__(**kwargs)

        with self.canvas:

            self.rect = Rectangle()

            tr = Clock.create_trigger(self.do_update_rect)

            self.bind(img = tr,size = tr,pos = tr)

        Clock.schedule_interval(self.update, 1 / 60.0)

    def do_update_rect(self,*args):

        texture = CoreImage(self.img).texture

        texture.wrap = 'repeat'

        self.rect.texture = texture

        self.rect.pos = self.pos

        self.rect.size = self.size

    def update(self, *args):

        t = Clock.get_boottime()

        self.rect.tex_coords = t*0.01,1,1+t*0.01,1,1+t*0.01,0,t*0.01,0

        # self.rect.tex_coords = 0,1,1,1,1,0,0,0

class MyApp(App):

    def build(self):

        return MyLayout()

if __name__ == '__main__':

    MyApp().run()