1 | import math |
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2 | |
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3 | import pymunk |
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4 | import pymunk.pygame_util |
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5 | |
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6 | from nagslang import render |
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7 | from nagslang.constants import COLLISION_TYPE_ENEMY, ZORDER_MID |
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8 | from nagslang.game_object import GameObject, SingleShapePhysicser, make_body |
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9 | from nagslang.mutators import FLIP_H |
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10 | from nagslang.resources import resources |
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11 | |
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12 | |
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13 | class Enemy(GameObject): |
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14 | """A base class for mobile enemies""" |
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15 | |
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16 | def __init__(self, space, position): |
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17 | self._setup_physics(space, position) |
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18 | self._setup_renderer() |
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19 | |
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20 | super(Enemy, self).__init__( |
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21 | self._physicser, self.renderer) |
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22 | self.zorder = ZORDER_MID |
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23 | |
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24 | def _get_image(self, name, *transforms): |
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25 | return resources.get_image('creatures', name, transforms=transforms) |
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26 | |
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27 | def _setup_physics(self, space, position): |
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28 | raise NotImplementedError |
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29 | |
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30 | def _setup_renderer(self): |
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31 | raise NotImplementedError |
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32 | |
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33 | def attack(self): |
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34 | raise NotImplementedError |
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35 | |
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36 | |
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37 | class PatrollingAlien(Enemy): |
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38 | is_moving = True # Always walking. |
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39 | |
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40 | def __init__(self, space, position, end_position): |
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41 | # An enemy that patrols between the two points |
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42 | super(PatrollingAlien, self).__init__(space, position) |
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43 | self._start_pos = position |
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44 | self._end_pos = end_position |
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45 | self._direction = 'away' |
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46 | |
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47 | def _setup_physics(self, space, position): |
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48 | self._body = make_body(10, pymunk.inf, position, 0.8) |
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49 | |
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50 | self._shape = pymunk.Circle(self._body, 30) |
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51 | |
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52 | self._shape.elasticity = 1.0 |
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53 | self._shape.friction = 0.05 |
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54 | self._shape.collision_type = COLLISION_TYPE_ENEMY |
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55 | self._physicser = SingleShapePhysicser(space, self._shape) |
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56 | self.impulse_factor = 50 |
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57 | self.angle = 0 |
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58 | |
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59 | def _setup_renderer(self): |
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60 | self.renderer = render.FacingSelectionRenderer({ |
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61 | 'left': render.TimedAnimatedRenderer( |
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62 | [self._get_image('alien_A_1.png'), |
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63 | self._get_image('alien_A_2.png')], 3), |
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64 | 'right': render.TimedAnimatedRenderer( |
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65 | [self._get_image('alien_A_1.png', FLIP_H), |
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66 | self._get_image('alien_A_2.png', FLIP_H)], 3), |
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67 | }) |
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68 | |
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69 | def get_render_angle(self): |
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70 | # No image rotation when rendering, please. |
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71 | return 0 |
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72 | |
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73 | def get_facing_direction(self): |
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74 | # Enemies can face left or right. |
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75 | if - math.pi / 2 < self.angle <= math.pi / 2: |
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76 | return 'right' |
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77 | else: |
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78 | return 'left' |
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79 | |
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80 | def _switch_direction(self): |
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81 | if self._direction == 'away': |
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82 | self._direction = 'towards' |
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83 | else: |
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84 | self._direction = 'away' |
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85 | |
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86 | def set_direction(self, dx, dy): |
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87 | self.angle = pymunk.Vec2d((dx, dy)).angle |
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88 | self._body.apply_impulse( |
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89 | (dx * self.impulse_factor, dy * self.impulse_factor)) |
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90 | |
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91 | def animate(self): |
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92 | # Calculate the step every frame |
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93 | if self._direction == 'away': |
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94 | target = self._end_pos |
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95 | else: |
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96 | target = self._start_pos |
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97 | x_step = 0 |
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98 | y_step = 0 |
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99 | if (target[0] < self._body.position[0]): |
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100 | x_step = max(-1, target[0] - self._body.position[0]) |
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101 | elif (target[0] > self._body.position[0]): |
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102 | x_step = min(1, target[0] - self._body.position[0]) |
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103 | if abs(x_step) < 0.5: |
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104 | x_step = 0 |
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105 | if (target[1] < self._body.position[1]): |
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106 | y_step = max(-1, target[1] - self._body.position[1]) |
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107 | elif (target[1] > self._body.position[1]): |
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108 | y_step = min(1, target[1] - self._body.position[1]) |
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109 | if abs(y_step) < 0.5: |
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110 | y_step = 0 |
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111 | if abs(x_step) < 1 and abs(y_step) < 1: |
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112 | self._switch_direction() |
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113 | self.set_direction(x_step, y_step) |
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114 | super(PatrollingAlien, self).animate() |
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