GNU 3DLDF Code Samples and Images

Author: Laurence D. Finston

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Last updated: April 29, 2006

Table of Contents

Top
Rotating Sphere
Interpenetrating Polygons
Sphere
Epicycloid Pattern
Contact
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Rotating Sphere

sphere_1.ldf. Indented version (plain text).

%% *** (3) Sphere. LDF 2005.05.02.

circle c[];
division_value := 64;
one_quarter_division_value := 1/4division_value;
three_quarters_division_value := 3/4division_value;
set c0 with_point_count division_value;
scale c0 (8, 0, 8);
rotate c0 by 90;
point p;
path q[];
p := get_point 0 c0;
q[division_value] += p;
pen thick_pen;
thick_pen := pencircle scaled (3.5, 3.5, 3.5);
pickup thick_pen;
step_value := 360 / division_value;
j := 1;
for i = 0 step step_value until 360 - step_value:
rotate c0 (0, step_value);
if (is_even j):
draw c0;
fi;
for k = 2 step 2 until one_quarter_division_value - 2:
q[k] += get_point (k) c0;
q[three_quarters_division_value + k]
+= get_point (three_quarters_division_value + k) c0;
endfor;
q[division_value] += get_point 0 c0;
j += 1;
endfor;
q[division_value] += cycle;
q[division_value] += ..;
draw q[division_value];
for i = 2 step 2 until one_quarter_division_value - 2:
q[i] += ..;
q[i] += cycle;
q[three_quarters_division_value + i] += ..;
q[three_quarters_division_value + i] += cycle;
draw q[i];
draw q[three_quarters_division_value + i];
endfor;
rotate current_picture by -25;
picture save_picture;
save_picture := current_picture;
clear current_picture;
message "Starting figures.";
for i = 1 upto 35:
rotate save_picture (0, 10);
beginfig(i);
output save_picture;
endfig;
message "Finished figure:";
show i;
endfor;
verbatim_metapost "bye;";
end;

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Interpenetrating Polygons

Indented version (plain text).

The images in PDF format: ships_1.pdf

2005-04-07. The images in a compressed (gzipped) PostScript file: ships_1.ps.gz
I find this format to be the most convenient. By pressing the page down button repeatedly in Ghostview, or holding it down, one has the effect of flipping through animation drawings. I tried to generate an animated MNG file, but it failed when I tried to use more than 10 input files. I'll have to look into a better way of creating animations.

pickup pencircle scaled 3;
reg_polygon p;
reg_polygon q;
focus f;
set f with_position (-5, 10, -10) with_direction (-5, 10, 10) with_distance 10;
p := unit_pentagon scaled 5 rotated (0, 20) shifted (0, 0, -5);
q := unit_hexagon scaled 5 rotated (90, 20) shifted (0, 1, 3);
beginfig(0);
path r;
r := (-5, -22) -- (15, -22) -- (15, 7) -- (-5, 7) -- cycle;
undraw r;
output current_picture with_focus f;
verbatim_metapost "boxit.b(currentpicture); path p; p = bpath(b);";
clear current_picture;
endfig;
for i = 1 upto 10:
beginfig(i);
shift p (0, 0, 3);
filldraw p with_draw_color red with_fill_color green;
filldraw q with_draw_color blue with_fill_color yellow;;
verbatim_metapost "undraw p;";
endfig with_focus f with_surface_hiding;
endfor;
end;

[Interpenetrating Polygons].

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Sphere

Indented version (plain text).

beginfig(1);
circle c[];

division_value := 64;
one_quarter_division_value := 1/4division_value;
three_quarters_division_value := 3/4division_value;

set c0 with_point_count division_value;
scale c0 (8, 0, 8);
rotate c0 by 90;

point p;
path q[];

q[division_value] += get_point 0 c0;

pen thick_pen;

thick_pen := pencircle scaled (2.5, 2.5, 2.5);

pickup thick_pen;

step_value := 360 / division_value;
j := 1;
for i = 0 step step_value until 360 - step_value:
rotate c0 (0, step_value);
if (is_even j):
draw c0;
fi;
for k = 2 step 2 until one_quarter_division_value - 2:
q[k] += get_point (k) c0;
q[three_quarters_division_value + k] += get_point (three_quarters_division_value + k) c0;
endfor;
q[division_value] += get_point 0 c0;
j += 1;
endfor;

q[division_value] += cycle;
q[division_value] += ..;
draw q[division_value];

for i = 2 step 2 until one_quarter_division_value - 2:
q[i] += ..;
q[i] += cycle;
q[three_quarters_division_value + i] += ..;
q[three_quarters_division_value + i] += cycle;
draw q[i];
draw q[three_quarters_division_value + i];
endfor;

rotate current_picture (-45, -15);

endfig;
end;


[Sphere].
Sphere

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Epicycloid Pattern

[LDF 2005.01.10.] I made this image with GNU 3DLDF 1.1.5.1, and I don't think I saved the code I used.


[Epicycloid Pattern].

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