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This gist show how to build a scrolling and repeating background with kivy
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.clock import Clock
from kivy.graphics import Rectangle
from kivy.core.image import Image as CoreImage
from kivy.core.window import Window
class MyWidget(Widget):
def __init__(self, **kw):
super(MyWidget, self).__init__(**kw)
with self.canvas:
texture = CoreImage('Sky_back_layer.png').texture
texture.wrap = 'repeat'
self.rect_1 = Rectangle(texture=texture, size=self.size, pos=self.pos)
texture = CoreImage('Vegetation_(middle_layer).png').texture
texture.wrap = 'repeat'
self.rect_2 = Rectangle(texture=texture, size=self.size, pos=self.pos)
texture = CoreImage('Ground_(front_layer).png').texture
texture.wrap = 'repeat'
self.rect_3 = Rectangle(texture=texture, size=self.size, pos=self.pos)
Clock.schedule_interval(self.txupdate, 0)
def txupdate(self, *l):
t = Clock.get_boottime()
#print t
self.rect_1.tex_coords = -(t * 0.001), 0, -(t * 0.001 + 10), 0, -(t * 0.001 + 10), -10, -(t * 0.001), -10
self.rect_2.tex_coords = -(t * 0.01), 0, -(t * 0.01 + 1), 0, -(t * 0.01 + 1), -1, -(t * 0.01), -1
self.rect_3.tex_coords = -(t * 0.1), 0, -(t * 0.1 + 1), 0, -(t * 0.1 + 1), -1, -(t * 0.1), -1
class MyApp(App):
def build(self):
return MyWidget(size=Window.size)
if __name__ == '__main__':
MyApp().run()

How might you change the tex_coord for a vertical scroll?

Owner

tshirtman commented May 23, 2017 edited

@Rusbens1 sorry i didn't see your question before, i don't have notifications about that.

you see that the current tex_coords is set this way

tex_coords = -(t * 0.001), 0, -(t * 0.001 + 10), 0, -(t * 0.001 + 10), -10, -(t * 0.001), -10

it's uv mapping, there are 4 sets of coordinates, one for each uv coord of the rectangle, if we remove the factors, it's currently of this form

t, 0, t + w, 0, t + w, h, t, h

which makes sense if you look at it like this

 4-----3
 |     |
 1-----2

(t, 0), (t + w, 0), (t + w, h), (t, h)
   1        2           3          4

if you want to scroll vertically, instead of horizontally, you just have to uset in v coords instead of u coords.

something like

 tex_coords = 0, -(t * 0.001), -10, -(t * 0.001), -10, -(t * 0.001 + 10), 0, -(t * 0.001 + 10)

might do the trick

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