How to position a part randomly on a part?

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#1

So what im trying to do is place a ore rock randomly on the base of the map but sometimes it will put itself completely off the part.

local pos = Vector3.new(math.random(-base.Size.x/2, base.Size.x/2), 2, math.random(-base.Size.z/2,base.Size.z/2))
rock:SetPrimaryPartCFrame(CFrame.new(pos.x,pos.y,pos.z))

3 Likes
#2

Do you wish that the rock copies the rotation of the base you are placing it on? Cause that is what this will do:

rock:SetPrimaryPartCFrame(base.CFrame * CFrame.new(pos))

This code treats pos as if its in the local space of the base you are trying to place it on.

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#3

Perhaps because you’re using math.random? It’s kinda old and I recommend using the new Random method.

Example

local newrandom = Random.new() 
local randomnumber = newrandom:NextNumber(0, 10)
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#4

this will keep the rock on the part, my code sometimes puts it off the part…

#5

Is the base part centered at the origin? If it’s not you’ll also need to add in it’s position to your random position.

Also, you might want to leave a little margin at the edges so the ore won’t spawn hanging off the edge of the part.

2 Likes
#6

already done and it still goes off.

#7

Don’t you want the rock to stay on the part?
this is the result of using this code, with the baseplate as the base and a random stack of 3 blocks being the rock.

local m = Instance.new("Model")
m.Parent = workspace
for k = 1, 50 do
	local base = workspace.Baseplate
	local rock = workspace.Model:Clone()
	local pos = Vector3.new(math.random(-base.Size.x/2, base.Size.x/2), base.Size.y/2, math.random(-base.Size.z/2,base.Size.z/2))
	rock:SetPrimaryPartCFrame(base.CFrame * CFrame.new(pos))
	rock.Parent = m
end

2328×980 140 KB

also if the basepart is rotated it will still work:

2326×980 122 KB

3 Likes
#8

did not work…

helppls

as you can see the rock is going off the part…

Code:

local pos = Vector3.new(math.random(-base.Size.x/2, base.Size.x/2), 2, math.random(-base.Size.z/2,base.Size.z/2))
rock:SetPrimaryPartCFrame(base.CFrame * CFrame.new(pos))

#9

Does your base have a BlockMesh inside it that makes the base appear smaller? also which part on the rock is the PrimaryPart?

#10

1: No it does not

2: the primary part is the rock mesh.

#11

what does the rock mesh look like when selected? like the bounding box.

#12

rock

#13

thats the selection.

#14

I do think this may be caused as you are placing the models relative to (0,0,0) not relative to the base position, so

SetPrimartPartCFrame(CFrame.new(base.Position + pos))

#15

wow

still goes off

#16

I am 98% sure that that should work…

Can you try printing

  1. the base position
  2. the random position and
  3. the combined positions
#17

1: 309.975342, 699.647339, -16.3491192
2: 197, 2, 99
3: 506.975342, 701.647339, 82.6508789

#18

Whats the base size?

#19

well its kinda random, it chooses a random base and gives it a random pos on that base…

#20

Does it use the base position before moving or after?
And can you give me the 3 numbers again but with the base pos aswell so i can see if any of the numbers dont match