How to randomly draw something once in love2d

Question

I'm currently trying to create brick breaker using love2d but the problem is whenever is used math.random() to generate random bricks the love application keeps running it multiple times and the brick moves constantly.

EDIT: So I want to generate bricks at particular column but the rows should be randomly selected. My basic idea was to do math.random(2) == 1 then drawing bricks using for loop but the problem is that it gets updated/drawn at every second and the bricks keeps on flickering/moving. I just want to randomly(only randomly select the y co-ordinate my x co-ordinate is fixed) to draw it once when you execute the code but its keep on flickering

The issue I'm facing - https://youtu.be/AJB5vH7yfHc

My code

    for y = 0, VIRTUAL_HEIGHT- 4, 10 do
        if math.random(2) == 1 then
            love.graphics.rectangle('line', VIRTUAL_WIDTH - 10, y, 5, 10)
        end
    end

Answer 1

Alright, after you edited the question, this sounds more like what you're talking about. Just take out that #column loop, and set it to create cells on the last column.

love.load()

--VIRTUAL_WIDTH, VIRTUAL_HEIGHT  = love .graphics .getDimensions()

block_pos  = {}  --  table to store block positions
rows, columns  = 30, 20  --  you decide how many

chance_of_block  = 33  --  % chance of placing a block

block_width  = math .floor( VIRTUAL_WIDTH /columns )
block_height  = math .floor( VIRTUAL_HEIGHT /rows )

col  = columns -1  --  don't loop through columns, just use final column

for  row = 0,  rows -1  do

    if love .math .random() *100 <= chance_of_block then
        local xpos  = col *block_width
        local ypos  = row *block_height

        block_pos[ #block_pos +1 ] = { x = xpos,  y = ypos }
    end  --  rand

end  --  #columns

r, g, b  = 0.5, 0.5, 0.0
love .graphics .setColor( r, g, b )

love.draw()

for b = 1, #block_pos do
    local block  = block_pos[b]

    love .graphics .rectangle( 'line',  block.x,  block.y,  block_width,  block_height )
end  --  #block_pos

Answer 2

generate block positions in love.load()

--VIRTUAL_WIDTH, VIRTUAL_HEIGHT  = love .graphics .getDimensions( )

block_pos  = {}  --  table to store block positions
rows, columns  = 5, 8  --  you decide how many

chance_of_block  = 75  --  % chance of placing a block

block_width  = math .floor( VIRTUAL_WIDTH /columns )
block_height  = math .floor( VIRTUAL_HEIGHT /rows )

for  row = 0,  rows -1  do
    for  col = 0,  columns -1  do

        if love .math .random() *100 <= chance_of_block then
            local xpos  = col *block_width
            local ypos  = row *block_height

            local red   = love .math .random()
            local green = love .math .random()
            local blue  = love .math .random()

            block_pos[ #block_pos +1 ] = { x = xpos,  y = ypos,  r = red,  g = green,  b = blue }
        end  --  rand

    end  --  #columns
end  --  #rows

(edited: realized row & column should start from 0 index, so they line up on the screen)

---

then draw them with love.draw()

for b = 1, #block_pos do
    local block  = block_pos[b]

    love .graphics .setColor( block.r,  block.g,  block.b )
    love .graphics .rectangle( 'fill',  block.x,  block.y,  block_width,  block_height )
end  --  #block_pos