source: anuga_core/source/anuga/geometry/aabb.py @ 7711

Last change on this file since 7711 was 7711, checked in by hudson, 14 years ago

Refactored geometry classes to live in their own folder.

File size: 2.4 KB
Line 
1# Allow children to be slightly bigger than their parents to prevent straddling of a boundary
2SPLIT_BORDER_RATIO    = 0.55
3
4class AABB:
5    """Axially-aligned bounding box class.
6    """
7   
8    def __init__(self, xmin, xmax, ymin, ymax):
9        """ Define axially-algned bounding box.
10            xmin is minimum x
11            xmax is maximum x (absolute coord, ie, not size)
12            ymin is minimum y
13            ymax is maximum y (absolute coord, ie, not size)
14        """
15        self.xmin = xmin   
16        self.xmax = xmax
17        self.ymin = ymin   
18        self.ymax = ymax
19
20
21    def __repr__(self):
22        return 'AABB(xmin:%f, xmax:%f, ymin:%f, ymax:%f)' \
23               % (round(self.xmin,1), round(self.xmax,1), round(self.ymin,1), round(self.ymax, 1)) 
24
25
26    def grow(self, amount):
27        """ Expand region by given amount.
28            amount is a multiplier, ie 1.1 will expand border by 10%.
29        """
30        self.ymax += (self.ymax-self.ymin)*amount
31        self.xmax += (self.xmax-self.xmin)*amount
32        self.ymin -= (self.ymax-self.ymin)*amount
33        self.xmin -= (self.xmax-self.xmin)*amount   
34
35       
36    def size(self):
37        """return size as (w,h)"""
38        return self.xmax - self.xmin, self.ymax - self.ymin
39
40       
41    def split(self, border=SPLIT_BORDER_RATIO):
42        """Split along shorter axis.
43           return 2 subdivided AABBs.
44        """
45       
46        width, height = self.size()
47        assert width >= 0 and height >= 0
48       
49        if (width > height):
50            # split vertically
51            return AABB(self.xmin, self.xmin+width*border, self.ymin, self.ymax), \
52                   AABB(self.xmax-width*border, self.xmax, self.ymin, self.ymax)
53        else:
54            # split horizontally       
55            return AABB(self.xmin, self.xmax, self.ymin, self.ymin+height*border), \
56                   AABB(self.xmin, self.xmax, self.ymax-height*border, self.ymax)   
57
58   
59    def is_trivial_in(self, test):
60        """ Is trivial in.
61            test an x,y point to test against the bounding box
62            return True if the test point falls within the bounding box
63        """
64        if (test.xmin < self.xmin) or (test.xmax > self.xmax):
65            return False       
66        if (test.ymin < self.ymin) or (test.ymax > self.ymax):
67            return False       
68        return True
69 
70    def contains(self, x, y):
71        return (self.xmin <= x <= self.xmax) and (self.ymin <= y <= self.ymax)
72       
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