Hi guys, the game that I working on is creating blocks with position of x in some range. But I realized that on the start of the game it always pick the same value like every time it picks 320. What is the problem or how can I fix it?
Also should always discard first few random values as the first few will always be the same due to some C thing
I prefer to use https://github.com/subsoap/defrng/blob/master/defrng/mt.lua for random numbers
Is that a lua or a defold thing, because that is really annoying.
If you’re talking about needing to clear the first few bad RNG it’s a Lua thing. Using MT avoids the issue.
It’s not really a defold or a lua thing, it is a computer thing. You should read more about it, because it’s really interesting*
*well i think it’s quite interesting
Thanks for reference, I am currently using it. However there is another problem
function init(self) self.last_pos = 100 create(self, "#diamond-factory") end function create(self, fac) local pos = vmath.vector3() pos.y = 480 local random_x = m.random(50, 590) while self.last_pos >= random_x - 100 or self.last_pos <= random_x + 100 do random_x = m.random(50, 590) end self.last_pos = random_x local pos_of_ball = go.get_position("/ball") pos.x = random_x factory.create(fac, pos) end
I am using this script to pick values of long distance. If the position of the last one is between “prev_x - 100 and prev_x + 100” then it should pick new value until it is OK. But the game crashes because of infinite loop. What is the problem ? Or how can I fix it? Any idea?
So, we start with
self.last_pos == 100, so let’s figure out what values of
random_x get us out of the loop.
self.last_pos >= random_x - 100is
random_x >= 201
self.last_pos <= random_x + 100is
random_x < 0
random_x can’t be less than
50, it will never be less than
0, so your
while loop will never exit.
Why loop like that? Can’t you pass in the correct min and max values to math.random()?
There is a ball which is moving from left to right and right to left all the game time, so when the ball reaches a block, then the next block must be far away from ball’s position on the reach point. I don’t know if it is clear
I gave different values to self.last_pos but same result
Sorry for flood but I solved the problem, It was my mistake…
while random_x >= self.last_pos - 200 and random_x <= self.last_pos + 200 do random_x = m.random(50, 590) end
This worked fine while self.last_pos is initially 320. Then the random_x value should be between 120 and 520. So thanks for ideas
Since you’re trying to ensure the delta (difference) between two objects is “large enough” you should rewrite the conditional to make that clear, like:
repeat random_x = math.random(50, 590) until math.abs(self.last_pos - random_x) >= 200
That’s far easier to understand: keep generating a random number until the delta between the random and the
self.last_pos is more than
I am going to remember that bit of code. it is handy!
@Pkeod thanks for the link! this module should really be included in Defold, the default math.random is very annoying due to this math.randomseed(os.clock()*100000000000) and even with that from my test the module from your link works a lot better out of box!
What are you doing to that poor seed?
Use math.randomseed(socket.gettime()) and optionally throw away the first random value.
@britzl maybe “math.randomseed(socket.gettime())” works fine when I need to pick a number from the big range, but for my example, I just tested it, when I have 3 elements array (table) and I need to pick 1 random element from this array 3 times - one after another (my case is I just instantiate 3 objects but the object can have 3 different sprites and in init() of the object I assign one of the spites randomly) - “math.randomseed(socket.gettime())” works really bad unfortunately, basically almost always picking the same value for all 3 object (calls). When I use math.randomseed(os.clock()*100000000000) - this works better but the linked library - works perfectly out of box without any additional lines…
I noticed that the default math.random works really bad when I need to pick a random element from some small array (small range of numbers math.random(1,3) for example) without this “os.clock()*100000000000” madness , so basically analogue to https://docs.yoyogames.com/source/dadiospice/002_reference/maths/real%20valued%20functions/choose.html which works excellent in GMS 2…
Ah, I see. Well, hmm, if you throw away the first one or two random numbers you start to get the kind of variation that is to be expected:
-- os.time() seems to work equally well math.randomseed(socket.gettime()) math.random() math.random() print(math.random(1,3))
Not optimal. Perhaps we can deal with this better internally in the engine…
exactly, it is a bit hacky, and given the number of questions on the forum about “Random does not work” I believe this is the problem which must be addressed given the fact how often random functionality needed in game development.
Here are some illustrations of “bad rng” drawing 4 colors randomly on a canvas I made a few years ago. I think the method was pick a random x,y and pick a random one of the 4 colors based on the RNG methods. So after a few seconds the patterns would emerge.
And “better rng”