哈哈哈，太爽了，纪念一下
surface line(float step = 5; color c1 =color (1,1,1); color c2 =color (0,0,0); float diffamb = 0.6){ point Pr = transform("raster",P); normal Nf = faceforward(normalize(N),I); float illum = comp(diffuse(Nf),0)*diffamb+1-diffamb; color res; if (mod(floor(comp(Pr,1)),step)==0) res = c1; else res = c2; Ci = res * illum; }
