Mathematical question: procedural generation of a galaxy

Question

I\'m going to make a space/trading/combat game that is completely procedurally generated. But, I know that storing all of the details of the whole galaxy in memory is unfeas

Answer 1

Suppose you start with a seed for the galaxy, i.e. 1234, take this seed, and generate 10000 random numbers, each one represents a star system. When you approach the star, you take the star's random number, and you it as a seed for a new random function. Generate a random number for the quantity of celestial bodies orbiting the star, and the generate one number for each body (always using the second random function)and so on. I dont know if this helps you, but you need to remember that the random functions, are internally chaotic, for a initial condition, the whole function changes.

The seed for the stars in the galaxy must produce always the same stars, the seed of the stars must produce the same bodies, etc.

You can always turn things more interesting using statistics, density calculations, improving the results. Check always that the functions will produce the same result for the same input.

Sorry if my english sucks, i'm from Argentina, and english language is not one of my trained qualities :p

PD: I'm doing the same type of game ;)

Answer 2

A random seed for each solar system is a viable solution but I have a feeling you're barking up the wrong tree here.

Can the player do anything to change what's there? (Say, build something, mine a depleatable resource etc?) If so, you'll have to save the state anyway.

Can the player look up what the place was like without actually having to go back there? (And if he can't, why not?!) Are you going to look it up or are you going to regenerate the entire solar system just to find out a piece of information about it? (the PRNG solution doesn't permit you to obtain only part of the solar system, you have to make the whole thing.)

Just how much detail is there anyway that you need to save?

Answer 3

As long as you call srandom() with the same seed, you'll get the same values out of random(). So, just base everything in a star system off a single call to srandom()... Then, you'll only need to store 1 integer (the seed) for a whole star system. Now thats compression!

Answer 4

You could build a pseudo random number of N digits from a certain seed (the "mother number"). Then, you divide the digits into groups and use them for answering your questions.

Example: N=20

-> one digit: how many additional jump gates?
-> three digits: seed for generating the respective lengths of each available jump
-> six digits: seed for generating this solar system
-> ten digits: seed for generating a new 20 digit seed for each linked solar system

Then recurse. Each system (with stable orbits etc.) gets generated at time 0, and you will have to calculate how it looks now.

Of course, this approach, starting from a mother system, would mean that the farther the current system is from the mother system, the longer it takes to generate its data. Also, this way makes a tree, not a net (which I would expect).

I think that it would be better to generate coordinates - use polar coordinates in the plane, and perhaps an ellipsoid in three dimensions.

Answer 5

I can vaguely recall this being done before. During the early 90's fractals were all the rage and I remember one company offering worlds to game programmers. The had created a whole infinite universe full of galaxies with suns and planets, event down to the valleys and textures of places on the planets. They were offering to find suitable virtual real estate to game developers. The game developers would get the software to render and use this, together with the exact coordinates to their propery in this fractal universe.

I've googled for a few minutes for "fractal game world planet universe" and such, but haven't found them. It might have been Pandromeda, but I can't quite remember.

You should study fractals for this idea. All you need is a continous field of numbers that you can recreate from a seed and then present those numbers as stars, planets and satellites with different properties.

Answer 6

If you're feeling brave, you could do worse than look at how Ian Bell did it for the original version of Elite