101 lines
2.7 KiB
Python
101 lines
2.7 KiB
Python
#!/usr/bin/env python
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""" pg.examples.stars
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We are all in the gutter,
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but some of us are looking at the stars.
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-- Oscar Wilde
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A simple starfield example. Note you can move the 'center' of
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the starfield by leftclicking in the window. This example show
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the basics of creating a window, simple pixel plotting, and input
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event management.
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"""
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import random
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import math
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import pygame as pg
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# constants
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WINSIZE = [640, 480]
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WINCENTER = [320, 240]
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NUMSTARS = 150
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def init_star(steps=-1):
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"creates new star values"
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dir = random.randrange(100000)
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steps_velocity = 1 if steps == -1 else steps * 0.09
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velmult = steps_velocity * (random.random() * 0.6 + 0.4)
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vel = [math.sin(dir) * velmult, math.cos(dir) * velmult]
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if steps is None:
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return [vel, [WINCENTER[0] + (vel[0] * steps), WINCENTER[1] + (vel[1] * steps)]]
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return [vel, WINCENTER[:]]
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def initialize_stars():
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"creates a new starfield"
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random.seed()
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stars = [init_star(steps=random.randint(0, WINCENTER[0])) for _ in range(NUMSTARS)]
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move_stars(stars)
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return stars
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def draw_stars(surface, stars, color):
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"used to draw (and clear) the stars"
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for _, pos in stars:
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pos = (int(pos[0]), int(pos[1]))
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surface.set_at(pos, color)
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def move_stars(stars):
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"animate the star values"
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for vel, pos in stars:
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pos[0] = pos[0] + vel[0]
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pos[1] = pos[1] + vel[1]
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if not 0 <= pos[0] <= WINSIZE[0] or not 0 <= pos[1] <= WINSIZE[1]:
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vel[:], pos[:] = init_star()
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else:
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vel[0] = vel[0] * 1.05
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vel[1] = vel[1] * 1.05
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def main():
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"This is the starfield code"
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# create our starfield
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stars = initialize_stars()
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# initialize and prepare screen
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pg.init()
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screen = pg.display.set_mode(WINSIZE)
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pg.display.set_caption("pygame Stars Example")
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white = 255, 240, 200
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black = 20, 20, 40
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screen.fill(black)
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clock = pg.time.Clock()
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# main game loop
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done = 0
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while not done:
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draw_stars(screen, stars, black)
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move_stars(stars)
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draw_stars(screen, stars, white)
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pg.display.update()
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for e in pg.event.get():
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if e.type == pg.QUIT or (e.type == pg.KEYUP and e.key == pg.K_ESCAPE):
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done = 1
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break
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if e.type == pg.MOUSEBUTTONDOWN and e.button == 1:
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WINCENTER[:] = list(e.pos)
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clock.tick(50)
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pg.quit()
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# So `python -m pygame.example.stars` will work.
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if __name__ == "__main__":
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main()
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# I prefer the time of insects to the time of stars.
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#
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# -- Wisława Szymborska
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