local light_dir = (light-location)/light_dist
local vis = light_visibility(location + light_dir*eps, light_dir, eps, light_dist, 1, sdf)
+ -- local vis = 1.0
local Idiff = math.max(normal*light_dir, 0)
local Ispec = math.pow(math.max(light_dir*reflected_ray,0),shiny)