Asymptote 折线 确定的曲面 怎么理解

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折线(0,0,0)--(0,0,1)--(1,0,1)--(1,0,0)--(1,1,0)--(1,1,1)--(0,1,1)-(0,1,0)--cycle
import three;
unitsize(2cm);
triple A = (0,0,0);
triple B = (0,0,1);
triple C = (1,0,1);
triple D = (1,0,0);
triple E = (1,1,0);
triple F = (1,1,1);
triple G = (0,1,1);
triple H = (0,1,0);
path3 p=A--B--C--D--E--F--G--H--cycle;
draw(p,red);
它确定的曲面为什么是
import three;
unitsize(2cm);
triple A = (0,0,0);
triple B = (0,0,1);
triple C = (1,0,1);
triple D = (1,0,0);
triple E = (1,1,0);
triple F = (1,1,1);
triple G = (0,1,1);
triple H = (0,1,0);
path3 p=A--B--C--D--E--F--G--H--cycle;
draw(surface(p), lightgrey);
draw(p,red);