I have a few quick questions about random number generation inside minecraft itself:

 

How do I ensure I am using the same seed that minecraft generates for my random numbers, as if I use my own external Random Number Generator it won't tie in with the minecraft seed so that with the same seed I get totally different results from stuff generated my way.

 

I guess I'd like to know what is the proper way to use random numbers for generation in my mod (same seed as minecraft, or new seed or whatever).

Are you just talking about the random seed for world gen?  or are you talking about any ranodm.

 

 

Assuming the first, you need to make sure your seed is saved and reused for that dimension each time in the future chunks/ect are generated.

I'm generating some stuff with my mod and I was wondering if I should get the map seed and ensure that any random generation is used off of that or whether I should embrace another (self generated) seed.....

 

Or to put it more succinctly:

// Walk through rules starting at last and determine if that rule is to be used instead
private int useRule(Bricks rules)
{
int ret = 0;
Random rnd = new Random();
for (int num = rules.bricks.size() -1; num > 0; num--)
{
	Brick brick = new Brick(rules.getBrick(num));
	if (rnd.nextInt(100)+1 <= brick.chance)
	{
	ret = num;
	break;
	}
}
return ret;
}

 

If I should use new Random or is there a minecraft generated random instead ?

Ah, gotcha now.

 

I have only done ore generation, not structure generation (thought I have looked at it).

 

I don't think you need to maintain the seed for that.  Someone may correct me on something to do with structures though.

Its been challenging, to be sure, (cutting a section from world and putting in text file that is easily editable, getting the placement so I can rotate stuff properly in the 4 directions and change the origin if need be) but well worth it so far I think (from a Java knowledge standpoint)