This is an attempt at understanding the procedural generation that was used to create the galaxies in the 1984 computer game Elite, based on information from http://wiki.alioth.net/
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89 lines
3.0 KiB
89 lines
3.0 KiB
11 years ago
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from classes.star import Star
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# Seed values from which the galaxy will be constructed.
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seed = [0x5A4A, 0x0248, 0xB753]
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galaxy_seed = seed
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#List to hold all the galaxies, represented as lists holding its stars as objects.
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galaxies = []
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star_bins = [] # Holds the six binary strings used to calculate a star's data.
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seed_bin = "" # Used to hold the binary value of each seed value in order to perform a roll-left.
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# Input variables used to look up a planet by its galaxy and star numbers.
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galaxy_num = ""
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star_num = ""
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DIGRAM_STRING = "@@LEXEGEZACEBISOUSESARMAINDIREA'ERATENBERALAVETIEDORQUANTEISRION"
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for galaxy in range(8):
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# Adds a new list to galaxies, into which new stars will be added.
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galaxies.append([])
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# List holding each set of values that will make up each star and its properties.
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star_twists = []
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for star in range(256):
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# If it's the first star, add the seed values, otherwise use the last three
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# values from the last twist.
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if star == 0:
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star_twists.append(galaxy_seed[:])
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else:
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# First two values are the last two from the previous twist.
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# Last one is the sum of the last twist's final three values modulo 65536.
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star_twists.append(star_twists[star - 1][4:6])
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star_twists[star].append(sum(star_twists[star - 1][3:6]) % 65536)
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# Add the last three values to the current twist by taking the previous three
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# values in the same twist modulo 65536.
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for extra_twists in range(3,6):
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star_twists[star].append(sum(star_twists[star][extra_twists - 3:extra_twists]) % 65536)
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# Convert the values in the current twist to binary.
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star_bins = []
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for ind, new_bin in enumerate(star_twists[star]):
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star_bins.append(bin(new_bin)[2:])
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# Append leading zeros to ensure each binary string is 16 characters long.
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star_bins[ind] = "0" * (16 - len(star_bins[ind])) + star_bins[ind]
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# Add a new star object to the current galaxy, using the newly-converted binary
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# strings to calculate its properties.
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galaxies[galaxy].append(Star(star_bins))
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# Perform an 8-bit roll-left operation on the seed values.
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# Basically, in every 8 bits of each value, the first binary digit becomes the last
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# binary digit.
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for ind, seed_val in enumerate(galaxy_seed):
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seed_bin = bin(seed_val)
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seed_bin = "0" * (16 - len(seed_bin[2:])) + seed_bin[2:]
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seed_bin = "0b" + seed_bin[1:8] + seed_bin[0] + seed_bin[9:16] + seed_bin[8]
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galaxy_seed[ind] = int(seed_bin, 2)
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# Get rid of now-redundant variables.
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del star_twists
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del star_bins
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while not galaxy_num == -1:
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try:
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galaxy_num = int(raw_input("Enter galaxy number: "))
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except ValueError:
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print "Not a number."
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continue
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else:
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if galaxy_num >= len(galaxies):
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print "There aren't that many galaxies."
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continue
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try:
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star_num = int(raw_input("Enter star number: "))
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except ValueError:
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print "Not a number."
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continue
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else:
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if star_num >= len(galaxies[galaxy_num]):
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print "There aren't that many stars."
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continue
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galaxies[galaxy_num][star_num].print_data(DIGRAM_STRING)
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