Instantly share code, notes, and snippets.

Embed
What would you like to do?
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()
@Rusbens1

This comment has been minimized.

Rusbens1 commented Apr 21, 2017

How might you change the tex_coord for a vertical scroll?

@tshirtman

This comment has been minimized.

Owner

tshirtman commented May 23, 2017

@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

@chaaken

This comment has been minimized.

chaaken commented May 7, 2018

Hey, I'm trying to understand how the repeat function works. If I remove the Clock Interval update I notice that the initial frame is not tiled. Regards Erik

@tshirtman

This comment has been minimized.

Owner

tshirtman commented May 8, 2018

@chaaken: hey, the repeats simply works because of the w and h factors in the equation i posted below, since it's between e.g 0.001 it means at 0.1% of the rect, it'll have already used the whole width/height of the texture, so what happens after that depends on the wrap mode, since i set repeat, it'll start over, there are other modes that for example just continue with the same pixel value as the last one, but on its own, the mode is not enough, you also need the tex_coords value that make it wrap.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment