bezier.lua

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

width, height = term.getSize()
midw = math.floor(width/2)
midh = math.floor(height/2)

p0 = vector.new(1, 1, 0)
p2 = vector.new(width, height, 0)

function quad_bezier(p0, p1, p2, step)

    local oldx = p0.x
    local oldy = p0.y

    for t=0, 1, step do
        local x1 = lerp(p0.x, p1.x, t)
        local y1 = lerp(p0.y, p1.y, t)
        local x2 = lerp(p1.x, p2.x, t)
        local y2 = lerp(p1.y, p2.y, t)
        local x = lerp(x1, x2, t)
        local y = lerp(y1, y2, t)

        paintutils.drawLine(oldx, oldy, x, y, colors.white)

        oldx = x
        oldy = y
    end
end

while true do
    local p1 = vector.new(1, height, 0)
    local event, button, x, y = os.pullEvent("mouse_drag")
    term.setBackgroundColor(colors.black)
    term.clear()
    p1.x, p1.y = x, y
    quad_bezier(p0, p1, p2, 0.2)
end

-- paintutils.drawLine(p0.x, p0.y, p1.x, p1.y, colors.white)