Created
January 27, 2015 22:57
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Kivy Polygon Intersection
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| class Polygon(EventDispatcher): | |
| abs_vertices = ListProperty([]) | |
| x = NumericProperty(0) | |
| y = NumericProperty(0) | |
| scale = NumericProperty(1) | |
| def __init__(self, **kwargs): | |
| super(Polygon, self).__init__(**kwargs) | |
| self.abs_vertices = [] | |
| def _get_rel_vertices(self): | |
| return [(x*self.scale+self.x, y*self.scale+self.y) for x, y in self.abs_vertices] | |
| vertices = AliasProperty(_get_rel_vertices, lambda *a: None, bind=("x", "y", "abs_vertices")) | |
| def collide_point(self, x, y): | |
| # This strangely happens. IDK | |
| if len(self.abs_vertices) == 0: | |
| warnings.warn("Polygon has no vertices: {0}".format(str(self)), RuntimeWarning, stacklevel=2) | |
| return False | |
| # If the point is a vertex, it's in the polygon | |
| if (x, y) in (tuple(i) for i in self.vertices): | |
| return True | |
| xs = [i[0] for i in self.vertices] | |
| ys = [i[1] for i in self.vertices] | |
| # if the point is outside of the polygon's bounding | |
| # box, it's not in the polygon | |
| if (x > max(*xs) or x < min(*xs)) or \ | |
| (y > max(*ys) or y < min(*ys)): | |
| return False | |
| xp1, yp1 = self.vertices[-1] # Start with first and last vertices | |
| count = 0 | |
| for xp2, yp2 in self.vertices: | |
| # Check if point is between lines y=yp1 and y=yp2 | |
| if y <= max(yp1, yp2) and y >= min(yp1, yp2): | |
| # Get the intersection with the line that passes | |
| # through p1 and p2 | |
| x_inters = float(xp2-xp1)*float(y-yp1)/float(yp2-yp1)+xp1 | |
| # If x is less than or equal to x_inters, | |
| # we have an intersection | |
| if x <= x_inters: | |
| count += 1 | |
| xp1, yp1 = xp2, yp2 | |
| # If the intersections are even, the point is outside of | |
| # the polygon. | |
| return count % 2 != 0 | |
| def collide_polygon(self, polygon): | |
| # Check for same polygon | |
| if self == polygon or self.vertices == polygon.vertices: | |
| return True | |
| # Sort by vertex number to reduce the number of iterations | |
| polys = sorted([self, polygon], key=lambda x: len(x.vertices)) | |
| rpolys = tuple(reversed(polys)) | |
| # Check for common vertices | |
| vs = (tuple(i) for i in polys[1].vertices) | |
| for x, y in polys[0].vertices: | |
| if (x, y) in vs: | |
| return True | |
| # Collide each point with the other polygon | |
| for p in rpolys: | |
| for x, y in p.vertices: | |
| if polys[rpolys.index(p)].collide_point(x, y): | |
| return True | |
| return False | |
| def collide_widget(self, wid): | |
| if isinstance(wid, Polygon): | |
| p = wid | |
| else: | |
| p = Polygon(vertices=[(0, 0), # bottom left | |
| (wid.width, 0), # bottom right | |
| (wid.width, wid.height), # top right | |
| (0, wid.height)], # top left | |
| x=wid.x, y=wid.y) | |
| return self.collide_polygon(p) | |
| class MultiShapePolygon(Polygon): | |
| shape = NumericProperty(0) | |
| shapes = ListProperty([]) | |
| _shapes = [] | |
| def __init__(self, **kwargs): | |
| super(MultiShapePolygon, self).__init__(**kwargs) | |
| self.shapes = self._shapes | |
| self.bind(shape=self.update_vertices) | |
| self.update_vertices() | |
| def random_shape(self, *args): | |
| self.shape = random.randint(0, len(self.shapes) - 1) | |
| def update_vertices(self, *args): | |
| self.abs_vertices = self.shapes[self.shape]["vertices"] |
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