\input fig4tex % 1. Definition of characteristic points \figinit{6cm, rea} % Points defining the cube \figpt 1:(0,0) \figpttraC 2:=1/1,0,0/ \figpttraC 3:=1/1,1,0/ \figpttraC 4:=1/0,1,0/ \figvectC 10(0,0,1)\figptstra 5=1,2,3,4/1,10/ \figset write(ptname=$P_#1$) % Points defining the plane \figptbary 11:[6,7 ; 1,2] \figptbary 12:[3,4 ; 1,1] \figptbary 13:[1,5 ; 1,1] % Three other intersections with the cube \figvectN 100 [11,12,13] \figvectP 101 [5,6]\figptinterlineplane 14 :[5,101; 11,100] \figvectP 101 [1,4]\figptinterlineplane 15 :[1,101; 11,100] \figvectP 101 [3,7]\figptinterlineplane 16 :[3,101; 11,100] % % 2. Creation of the graphical file \figset projection(psi=-55, theta=30) \figdrawbegin{} \figdrawline[1,2,3]\figdrawline[5,6,7,8,5] \figdrawline[1,5]\figdrawline[2,6]\figdrawline[3,7] \figset(dash=4)\figdrawline[1,4,3]\figdrawline[4,8] \figset(alpha=0.3,color=\Redrgb, filmode=yes) \figdrawline[16,12,15,13,14,11,16]\figset(alpha=1, filmode=no) \figset(width=1,color=\Redrgb)\figdrawline[16,12,15,13] \figset(dash=1)\figdrawline[13,14,11,16] \figdrawend % 3. Writing text on the figure \def\dist{2pt} \figvisu{\figBoxA}{Intersection of a plane and a cube.}{ % Show vertices of the cube \figwritesw 1:(\dist)\figwritese 2:(\dist) \figwritee 3:(\dist)\figwritenw 4:(\dist) \figwritenw 5:(\dist)\figwritese 6:(\dist) \figwritene 7:(\dist)\figwritenw 8:(\dist) % Show points defining the plane \figset write(mark=$\bullet$) \figwritep[11,12,13] } \centerline{\box\figBoxA} \bye