def test_get_mass(self):
chunk = Chunk()
self.assertEquals(chunk.get_mass(), 0.0, "bad initial mass")
shard1 = Disc(gold, 5)
shard2 = Block(gold, self.unitsquare)
chunk.shards = [shard1, shard2]
self.assertEquals(chunk.get_mass(), (25 * pi + 1) * gold.density,
"bad mass")
def test_get_moment(self):
chunk = Chunk()
self.assertEquals(chunk.get_moment(), 0.0, "bad initial moment")
shard1 = Disc(gold, 2, (10, 20))
shard2 = Block(gold, self.unitsquare, (100, 200))
chunk.shards = [shard1, shard2]
expected = shard1.get_moment() + shard2.get_moment()
self.assertEquals(chunk.get_moment(), expected, "bad moment")
def test_offset_shards(self):
chunk = Chunk()
shard1 = Disc(gold, 5, (10, 20))
shard2 = Block(gold, self.unitsquare, (30, 40), center=True)
chunk.shards = [shard1, shard2]
chunk._offset_shards((+2, -3))
offset1 = chunk.shards[0].get_centroid()
self.assertEquals(offset1, (12, 17), "bad shard1 offset")
offset2 = chunk.shards[1].get_centroid()
self.assertEquals(offset2, (32, 37), "bad shard2 offset")
def test_center_of_gravity(self):
chunk = Chunk()
self.assertEquals(chunk._center_of_gravity(), (0, 0), "bad COG0")
shard1 = Disc(gold, 2, (10, 20))
chunk = Chunk()
chunk.shards = (shard1,)
cog = chunk._center_of_gravity()
self.assertAlmostEquals(cog[0], 10, msg="bad COG1 x")
self.assertAlmostEquals(cog[1], 20, msg="bad COG1 y")
verts = [(99, 49), (99, 51), (101, 51), (101, 49)]
shard2 = Block(gold, verts)
chunk.shards = (shard2,)
self.assertEquals(chunk._center_of_gravity(), (100, 50), "bad COG2")
chunk.shards = (shard1, shard2)
totalMass = shard1.mass + shard2.mass
x = (10 * shard1.mass + 100 * shard2.mass) / totalMass
y = (20 * shard1.mass + 50 * shard2.mass) / totalMass
self.assertEquals(chunk._center_of_gravity(), (x, y), "bad COG3")
