1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
|
% D. Roegel
% Three orthogonal projections of a tetrahedron
% January 7, 2001
% roegel@loria.fr
verbatimtex
%&latex
\documentclass{article}
\begin{document}
etex
input 3dgeom; % definitions for geometry
input 3danim; % animations
% We modify some of the default settings.
output_res:=72;
drawing_scale:=7cm;
filled_faces:=false;
show_animation_parameters:=true;
%projection_type:=1; % parallel projection
%================ DEFINITION OF OBJECT (BEGIN) =========================
vardef def_fig(expr inst)=
new_obj_points(inst,28); % 28 points 4+3*(4+4)
set_fig_points(inst);
enddef;
% Definition of the points that belong to the general figure.
vardef set_fig_points(expr inst)=
set_point(1)(0.3,0.45,0.8); % A
set_point(2)(0.6,0.45,0.8); % B
set_point(3)(0.5,0.6,0.5); % C
set_point(4)(0.5,0.3,0.5); % D
% the three planes (four corners at a time)
% horizontal
set_point(5)(0,0,-.2);
set_point(6)(1,0,-.2);
set_point(7)(1,1,-.2);
set_point(8)(0,1,-.2);
% vertical left
set_point(9) (-.45,0,0);
set_point(10)(-.45,1,0);
set_point(11)(-.45,1,1);
set_point(12)(-.45,0,1);
% vertical front
set_point(13)(0,-.45,0);
set_point(14)(1,-.45,0);
set_point(15)(1,-.45,1);
set_point(16)(0,-.45,1);
% we now compute the verticals and therefore introduce plane structures
new_plane(f)(9,10,11);
new_plane(g)(13,14,15);
new_plane(h)(5,6,7);
% bottow figure
def_vert_pl(17)(1)(h);
def_vert_pl(18)(2)(h);
def_vert_pl(19)(3)(h);
def_vert_pl(20)(4)(h);
% left figure
def_vert_pl(21)(1)(f);
def_vert_pl(22)(2)(f);
def_vert_pl(23)(3)(f);
def_vert_pl(24)(4)(f);
% front figure
def_vert_pl(25)(1)(g);
def_vert_pl(26)(2)(g);
def_vert_pl(27)(3)(g);
def_vert_pl(28)(4)(g);
free_plane(h);free_plane(g);free_plane(f);
enddef;
% Method to draw a general figure
vardef draw_fig(expr inst)=
% tetrahedron
pickup pencircle scaled 1pt;
drawoptions();
draw_line(1,2);draw_line(1,3);draw_line(2,3);
draw_line(2,4);draw_line(3,4);
drawoptions(dashed withdots);draw_line(1,4);
drawoptions();
% projection on f:
draw_line(21,22);draw_line(21,23);draw_line(21,24);
draw_line(22,23);draw_line(22,24);draw_line(23,24);
% projection on g:
draw_line(25,26);draw_line(25,27);draw_line(25,28);
draw_line(26,27);draw_line(26,28);draw_line(27,28);
% projection on h:
draw_line(17,18);draw_line(17,19);draw_line(17,20);
draw_line(18,19);draw_line(18,20);draw_line(19,20);
pickup pencircle scaled .4pt;
% les plans
draw_line(5,6);draw_line(6,7);draw_line(7,8);draw_line(8,5);
draw_line(9,10);draw_line(10,11);draw_line(11,12);draw_line(12,9);
draw_line(13,14);draw_line(14,15);draw_line(15,16);draw_line(16,13);
pickup pencircle scaled .4pt;
% dotted projection lines:
save i;drawoptions(dashed evenly);
for i:=1 upto 4: draw_line(i,i+16);endfor;
for i:=1 upto 4: draw_line(i,i+20);endfor;
for i:=1 upto 4: draw_line(i,i+24);endfor;
% and a few labels:
label_obj.top(btex $A$ etex,1);
label_obj.llft(btex $B$ etex,2);
label_obj.lrt(btex $C$ etex,3);
label_obj.llft(btex $D$ etex,4);
label_obj.bot(btex $H$ etex,7);
label_obj.top(btex $F$ etex,12);
label_obj.llft(btex $G$ etex,14);
enddef;
assign_obj("figa","fig");
%================ DEFINITION OF OBJECT (END) =========================
% Call of drawing instruction
%for i:=0 upto 20:%99:
i=12;
beginfig(100+i);
% Positionning of the observer
set_point_(Obs)(4*cosd(3.6*i),4*sind(3.6*i),2.2);
Obs_phi:=90;Obs_dist:=2;point_of_view_obj("figa",1,Obs_phi);
draw_obj("figa"); % main figure
endfig;
%endfor; show_animation_bbox;
end.
|
