function polygon( x, y, radius, sides, rotation)
    local triangles = {}; //each triangle holds 3 points. each point is {x,y}
    rotation = rotation or 0;

    for i=0, 360, 360/sides do

        local p1,p2,p3 = {},{},{};

        p1[0] = x + math.cos(i/360 + rotation) * radius;
        p1[1] = y + math.sin(i/360 + rotation) * radius;

        p2[0] = x;
        p2[1] = y;

        p3[0] = x + math.cos((i+360/sides)/360 + rotation) * radius;
        p3[1] = y + math.sin((i+360/sides)/360 + rotation) * radius;

        local tri = {p1,p2,p3};
        table.insert(triangles, tri);

    end

    for k,v in pairs(triangles) do

        //Draw your polygon.

    end
end