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1 #############################################################################
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2 #
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3 # Copyright (c) 2010 by Casey Duncan and contributors
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4 # All Rights Reserved.
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5 #
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6 # This software is subject to the provisions of the MIT License
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7 # A copy of the license should accompany this distribution.
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8 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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9 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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10 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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11 #
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12 #############################################################################
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13
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14 __version__ = '$Id$'
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15
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16
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17 class EulerMovement(object):
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18 """System that applies entity movement to position using Euler's method
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19
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20 :param position_component: Name of :class:`grease.component.Position`
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21 component to update.
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22 :param movement_component: Name of :class:`grease.component.Movement`
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23 component used to update position.
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24 """
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25
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26 def __init__(self, position_component='position', movement_component='movement'):
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27 self.position_component = position_component
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28 self.movement_component = movement_component
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29
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30 def set_world(self, world):
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31 """Bind the system to a world"""
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32 self.world = world
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33
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34 def step(self, dt):
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35 """Apply movement to position"""
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36 assert self.world is not None, "Cannot run with no world set"
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37 for position, movement in self.world.components.join(
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38 self.position_component, self.movement_component):
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39 movement.velocity += movement.accel * dt
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40 position.position += movement.velocity * dt
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41 position.angle += movement.rotation * dt
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42
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