beta = asin(front_setback / front_height);
uf = [-sin(beta), cos(beta)];
-ur = [-uf[0], uf[1]];
+ur = [ -uf[1], uf[0]];
pp = [0, 0];
pq = pp + uf*front_height + ur*eclip_ra_offset;
pr = [ pq[0] - eclip_base_offset + eclip_wall_offset, 0 ];
+echo("uf ur P Q R", uf, ur, pp, pq, pr);
+
module Sketch(){
polygon([pq, pp, pr]);
}