My sanity just left me

gistfile1.txt

function road_points() =
	let(p=perimeter_points(),
    p1=p[1],
    p2=p[2],
    p3=p[3],
		pn=p[len(p)-1],
		rb=road_width_b/2,
		ra=road_width_a/2,
    la=length_vector(pn),
    // Scale vector pn with road radius b
    a=scale_vector(pn,(la-rb)/la),
    o=big_circle_origin(),
    // Define 2 vectors for the line parallel to p2-p3 with road radius a
    pp2=p2+perpendicular_point(p3,p2,ra),
    pp3=p3+perpendicular_point(p3,p2,ra),
    // Determine intersection point for point b
		b=circle_line_intersection(pp2-o,pp3-o,radius_big_circle+rb)[1]+o,
    lc=length_vector(p2-p1),
		c=scale_vector(p2-p1, (lc-ra/cos(39))/lc)+p1,
    ld=length_vector(p3-p2),
    d=scale_vector(p3-p2,(ld-rb)/ld)+p2,
		cp=calculate_center_arch_point(d,a,radius_big_circle+rb),
    curve=bezier_curve_points([a,cp,d],20)
	)
	concat(
		[for(i = [2:len(p)-1]) p[i]],
		[a],
		filter(curve, function(p) p[0] < b[0]),
    [b],
		[c]
	);