dinking around with lua

motionsickness.lua

function lerp(a,b,t) return (1-t)*a + t*b end


function new_star()

    local rx = love.math.random() * 20
    local ry = love.math.random() * 12

    if (love.math.random() < 0.5) then
        rx = rx * -1.0
    end

    if (love.math.random() < 0.52) then
        ry = ry * -1.0
    end

    local s = {x=(ox + rx), y=(oy + ry), dx=0.0, dy=0.0}
    s.dx = lerp(0.0, rx, 1.0)
    s.dy = lerp(0.0, ry, 1.0)

    --print (s.x .. " " .. s.y .. " " .. s.dx .. " " .. s.dy)
    return s
end


function love.load()
    ox, oy = love.graphics.getWidth()/2, love.graphics.getHeight()/2

    star_count = 250

    stars = {}
    for i=1,star_count do
        star = new_star()
        stars[i] = star
    end


    local width = love.graphics.getWidth();
    local height = love.graphics.getHeight();

    -- Simulate a bunch to make it look more interesting at the start
    for p=1, 1500 do
            
        for i=1,star_count do
            local s = stars[i]

            s.x = lerp(s.x, s.x + s.dx, 0.05)
            s.y = lerp(s.y, s.y + s.dy, 0.05)

            stars[i] = s
            --print (stars[i].x .. " " .. stars[i].y .. " " .. stars[i].dx .. " " .. stars[i].dy)
        end

        for i=1,star_count do
            if stars[i].x > width or stars[i].x < 0 then
                stars[i] =  new_star()
            elseif stars[i].y > height or stars[i].y < 0 then
                stars[i] = new_star()
            end
        end
    end
end



function love.draw()

    love.graphics.setColor(1, 1, 1)
    for i=1,star_count do
        love.graphics.rectangle("fill", stars[i].x, stars[i].y, 2, 2)
    end
end

function love.update(dt)

    local width = love.graphics.getWidth();
    local height = love.graphics.getHeight();

    for i=1,star_count do
        local s = stars[i]

        s.x = lerp(s.x, s.x + s.dx, 0.05)
        s.y = lerp(s.y, s.y + s.dy, 0.05)

        stars[i] = s
        --print (stars[i].x .. " " .. stars[i].y .. " " .. stars[i].dx .. " " .. stars[i].dy)
    end

    for i=1,star_count do
        if stars[i].x > width or stars[i].x < 0 then
            stars[i] =  new_star()
        elseif stars[i].y > height or stars[i].y < 0 then
            stars[i] = new_star()
        end
    end
end