% D. Roegel, 7 January 2001 % roegel@loria.fr verbatimtex %&latex \documentclass{article} \usepackage{mathpple} \begin{document} etex input 3danim input 3dgeom output_res:=72; drawing_scale:=10cm; numeric lsa,lsb,lsc,aasc,aasb,absc; lsa=9;lsb=8;lsc=4;aasc=60;aasb=40;absc=30; vardef def_T(expr inst)= new_obj_points(inst,4); % 4 points set_T_points(inst); enddef; vardef set_T_points(expr inst)= save hp,kp,sa,sc,inter;new_point(h);new_point(k); set_point(1)(0,0,0); % S set_point(2)(lsa,0,0); % A set_point(4)(lsc*cosd(aasc),lsc*sind(aasc),0); % C vec_diff_(h,pnt(2),pnt(1)); vec_unit_(h,h);vec_mult_(h,h,lsb*cosd(aasb)); vec_sum_(h,h,pnt(1)); vec_diff_(k,pnt(4),pnt(1)); vec_unit_(k,k);vec_mult_(k,k,lsb*cosd(absc)); vec_sum_(k,k,pnt(1)); new_plane(hp)(1,1,1); new_plane(kp)(1,1,1); new_line(sa)(1,2); new_line(sc)(1,4); new_line(inter)(1,1); def_orth_pl_l_p_(hp)(sa)(h); def_orth_pl_l_p_(kp)(sc)(k); if def_inter_l_pl_pl(inter)(hp)(kp): % there is an intersection if def_point_at(3,-lsb,1)(inter): else: message "PROBLEM"; fi; else: message "PROBLEM"; set_point(3)(1,1,1); fi; free_line(inter);free_line(sc);free_line(sa); free_plane(kp);free_plane(hp); free_point(k);free_point(h); enddef; vardef draw_T(expr inst)= draw_line(1,2);draw_line(1,4);draw_line(1,3); draw_line(2,3);draw_line(3,4); drawoptions(dashed evenly); draw_line(2,4); drawoptions(); label_obj.bot(btex $S$ etex,1); label_obj.rt(btex $A$ etex,2); label_obj.top(btex $B$ etex,3); label_obj.lft(btex $C$ etex,4); enddef; assign_obj("tetra","T"); %for i:=0 upto 20: i=0; beginfig(100+i); % Observator set_point_(Obs)(20*cosd(3.6*i-150),20*sind(3.6*i-150),6); Obs_phi:=90;Obs_dist:=2;point_of_view_obj("tetra",1,Obs_phi); draw_obj("tetra"); endfig; %endfor; end.