83 lines
2.3 KiB
Python
83 lines
2.3 KiB
Python
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'''
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Custom shape & collide widget
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=============================
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This is a Triangle widget with a triangle shape based on 3 points (p1, p2, p3),
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plus a custom collision function.
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The p1, p2, p3 are automatically calculated from the position and the size of
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the Widget bounding box. We are using them to draw the triangle shape.
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(Please note in the kv the special case for Scatter.)
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Then we need to setup a new collision function to collide only on the triangle.
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We are using a external method that will check if a point is inside a polygon
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(we consider our triangle as a polygon).
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'''
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import kivy
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kivy.require('1.0.8')
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from kivy.uix.scatter import Scatter
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from kivy.properties import ListProperty
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from kivy.lang import Builder
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Builder.load_string('''
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<Triangle>:
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# example for doing a triangle
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# this will automatically recalculate pX from pos/size
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p1: 0, 0
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p2: self.width, 0
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p3: self.width / 2, self.height
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# If you use a Widget instead of Scatter as base class, you need that:
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#p1: self.pos
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#p2: self.right, self.y
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#p3: self.center_x, self.top
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# draw something
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canvas:
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Color:
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rgb: 1, 0, 0
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Triangle:
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points: self.p1 + self.p2 + self.p3
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''')
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def point_inside_polygon(x, y, poly):
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'''Taken from http://www.ariel.com.au/a/python-point-int-poly.html
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'''
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n = len(poly)
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inside = False
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p1x = poly[0]
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p1y = poly[1]
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for i in range(0, n + 2, 2):
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p2x = poly[i % n]
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p2y = poly[(i + 1) % n]
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if y > min(p1y, p2y):
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if y <= max(p1y, p2y):
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if x <= max(p1x, p2x):
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if p1y != p2y:
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xinters = (y - p1y) * (p2x - p1x) / (p2y - p1y) + p1x
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if p1x == p2x or x <= xinters:
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inside = not inside
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p1x, p1y = p2x, p2y
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return inside
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class Triangle(Scatter):
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p1 = ListProperty([0, 0])
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p2 = ListProperty([0, 0])
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p3 = ListProperty([0, 0])
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def collide_point(self, x, y):
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x, y = self.to_local(x, y)
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return point_inside_polygon(x, y,
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self.p1 + self.p2 + self.p3)
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if __name__ == '__main__':
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from kivy.base import runTouchApp
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runTouchApp(Triangle(size_hint=(None, None)))
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