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@gottadiveintopython
Created April 6, 2018 16:10
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simple gradient fill (GLSL, Kivy)
from kivy.app import runTouchApp
from kivy.core.window import Window
from kivy.factory import Factory
from kivy.lang import Builder
from kivy.graphics import RenderContext
from kivy.properties import StringProperty
Builder.load_string(r'''
<ShaderWidget>:
canvas:
Rectangle:
pos: self.pos
size: self.size
''')
class ShaderWidget(Factory.Widget):
fs = StringProperty(None)
def __init__(self, **kwargs):
self.canvas = RenderContext(
use_parent_projection=True,
use_parent_modelview=True,
use_parent_frag_modelview=True)
super().__init__(**kwargs)
def on_fs(self, __, value):
shader = self.canvas.shader
old_value = shader.fs
shader.fs = value
if not shader.success:
shader.fs = old_value
raise Exception('Failed to compile GLSL.')
def on_size(self, __, size):
self.canvas['resolution'] = [float(size[0]), float(size[1]), ]
GLSL_CODE = '''
uniform vec2 resolution;
void main(void)
{
float sx = gl_FragCoord.x / resolution.x;
float sy = gl_FragCoord.y / resolution.y;
gl_FragColor = vec4( 1.0, sx, sy, 1.0);
}
'''
root = ShaderWidget(fs=GLSL_CODE)
runTouchApp(root)
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