Correct. Both libraries are fundamentally 2D with no 3D support, besides some typical "3D Graphing" features. You should be able to figure out simple shapes easily enough. Beyond that, especially once you get into overlapping vertices in the visual projection, figuring out what is visible and drawing in a sensible order can get hairy, and a pure-ish Perl solution would best be measured in seconds per frame, not the inverse.

So, my advice would be, either keep it very simple, and learn some fun math, or embrace a much bigger library from the start. Whatever you decide, you might also try out something like Blender (free 3D software) to rapidly prototype your models and boost your visual comprehension. Good luck! Come back and post your creation.

I'll show you what i've been doing. I managed to make my program work, but i'm not gonna continue with the same way. So here's the code, i hope you're not going to laugh. Let's call this a robust attempt:

use GD;
use constant PI    => 4 * atan2(1, 1);
$ima = new GD::Image(800,800);
$black = $ima->colorAllocate(0,0,0);
$green=$ima->colorAllocate(0,255,0);
$ima->setThickness(3);
$data = $ima->gifanimbegin(1,0);

$im = new GD::Image(800,800);
$black = $im->colorAllocate(0,0,0);
$green=$im->colorAllocate(0,255,0);
$white=$im->colorAllocate(0,0,0);
$im->setThickness(3);
@een=(360,360,80);
@twee=(440,360,80);
@drie=(440,360,0);
@vier=(360,360,0);
$x1 =$een[0] + sqrt($een[2]**2/2);
$y1=$een[1] - sqrt($een[2]**2/2);
$x2 =$twee[0] + sqrt($twee[2]**2/2);
$y2=$twee[1] - sqrt($twee[2]**2/2);
$x3 =$drie[0] + sqrt($drie[2]**2/2);
$y3=$drie[1] - sqrt($drie[2]**2/2);
$x4 =$vier[0] + sqrt($vier[2]**2/2);
$y4=$vier[1] - sqrt($vier[2]**2/2);
$xx1=$x1;
$xx2=$x2;
$xx3=$x3;
$xx4=$x4;
$yy1=$y1+80;
$yy2=$y2+80;
$yy3=$y3+80;
$yy4=$y4+80;
$im->line($x1,$y1,$x2,$y2,$green);
$im->line($x2,$y2,$x3,$y3,$green);
$im->line($x3,$y3,$x4,$y4,$green);
$im->line($x4,$y4,$x1,$y1,$green);
$im->line($xx1,$yy1,$xx2,$yy2,$green);
$im->line($xx2,$yy2,$xx3,$yy3,$green);
$im->line($xx3,$yy3,$xx4,$yy4,$green);
$im->line($xx4,$yy4,$xx1,$yy1,$green);
$im->line($x1,$y1,$xx1,$yy1,$green);
$im->line($x2,$y2,$xx2,$yy2,$green);
$im->line($x3,$y3,$xx3,$yy3,$green);
$im->line($x4,$y4,$xx4,$yy4,$green);
$data.=$im->gifanimadd(0,0,0,1);
$teller = 0;
again:
for($x=PI/4;$x<=PI/2;$x+=PI/8){
$img = new GD::Image(800,800);
$black = $img->colorAllocate(0,0,0);
$green=$img->colorAllocate(0,255,0);
$white=$img->colorAllocate(0,0,0);
$img->setThickness(3);
@een=(360,360,80);
@twee=(440,360,80);
@drie=(440,360,0);
@vier=(360,360,0);
$straal = sqrt((40*40)+(40*40));
$yh = $straal * sin($x);
$hoogte =$yh-40;
$xv = sqrt($straal**2-$yh**2);
$xver = 40 - $xv;
$een[0]+=$xver;
$een[2]+=$hoogte;
$twee[0]+=$hoogte;
$twee[2]-=$xver;
$drie[0]-=$xver;
$drie[2]-=$hoogte;
$vier[0]-=$hoogte;
$vier[2]+=$xver;
if($een[2]>0){
$x1 =$een[0] + sqrt($een[2]**2/2);
$y1=$een[1] - sqrt($een[2]**2/2);}
else{
$x1 =$een[0] - sqrt($een[2]**2/2);
$y1=$een[1] + sqrt($een[2]**2/2);}
if($twee[2]>0){
$x2 =$twee[0] + sqrt($twee[2]**2/2);
$y2=$twee[1] - sqrt($twee[2]**2/2);}
else{
$x2 =$twee[0] - sqrt($twee[2]**2/2);
$y2=$twee[1] + sqrt($twee[2]**2/2);}
if($drie[2]>0){
$x3 =$drie[0] + sqrt($drie[2]**2/2);
$y3=$drie[1] - sqrt($drie[2]**2/2);}
else{
$x3 =$drie[0] - sqrt($drie[2]**2/2);
$y3=$drie[1] + sqrt($drie[2]**2/2);}
if($vier[2]>0){
$x4 =$vier[0] + sqrt($vier[2]**2/2);
$y4=$vier[1] - sqrt($vier[2]**2/2);}
else{
$x4 =$vier[0] - sqrt($vier[2]**2/2);
$y4=$vier[1] + sqrt($vier[2]**2/2);}
$xx1=$x1;
$xx2=$x2;
$xx3=$x3;
$xx4=$x4;
$yy1=$y1+80;
$yy2=$y2+80;
$yy3=$y3+80;
$yy4=$y4+80;
$img->line($x1,$y1,$x2,$y2,$green);
$img->line($x2,$y2,$x3,$y3,$green);
$img->line($x3,$y3,$x4,$y4,$green);
$img->line($x4,$y4,$x1,$y1,$green);
$img->line($xx1,$yy1,$xx2,$yy2,$green);
$img->line($xx2,$yy2,$xx3,$yy3,$green);
$img->line($xx3,$yy3,$xx4,$yy4,$green);
$img->line($xx4,$yy4,$xx1,$yy1,$green);
$img->line($x1,$y1,$xx1,$yy1,$green);
$img->line($x2,$y2,$xx2,$yy2,$green);
$img->line($x3,$y3,$xx3,$yy3,$green);
$img->line($x4,$y4,$xx4,$yy4,$green);
$data.=$img->gifanimadd(0,0,0,1);
}
$img = new GD::Image(800,800);
$black = $img->colorAllocate(0,0,0);
$green=$img->colorAllocate(0,255,0);
$white=$img->colorAllocate(0,0,0);
$img->setThickness(3);
@een=(360,360,80);
@twee=(440,360,80);
@drie=(440,360,0);
@vier=(360,360,0);
$yh = $straal * sin((PI/8)*5);
$hoogte =$yh-40;
$xv = sqrt($straal**2-$yh**2);
$xver = 40 + $xv;
$een[0]+=$xver;
$een[2]+=$hoogte;
$twee[0]+=$hoogte;
$twee[2]-=$xver;
$drie[0]-=$xver;
$drie[2]-=$hoogte;
$vier[0]-=$hoogte;
$vier[2]+=$xver;
if($een[2]>0){
$x1 =$een[0] + sqrt($een[2]**2/2);
$y1=$een[1] - sqrt($een[2]**2/2);}
else{
$x1 =$een[0] - sqrt($een[2]**2/2);
$y1=$een[1] + sqrt($een[2]**2/2);}
if($twee[2]>0){
$x2 =$twee[0] + sqrt($twee[2]**2/2);
$y2=$twee[1] - sqrt($twee[2]**2/2);}
else{
$x2 =$twee[0] - sqrt($twee[2]**2/2);
$y2=$twee[1] + sqrt($twee[2]**2/2);}
if($drie[2]>0){
$x3 =$drie[0] + sqrt($drie[2]**2/2);
$y3=$drie[1] - sqrt($drie[2]**2/2);}
else{
$x3 =$drie[0] - sqrt($drie[2]**2/2);
$y3=$drie[1] + sqrt($drie[2]**2/2);}
if($vier[2]>0){
$x4 =$vier[0] + sqrt($vier[2]**2/2);
$y4=$vier[1] - sqrt($vier[2]**2/2);}
else{
$x4 =$vier[0] - sqrt($vier[2]**2/2);
$y4=$vier[1] + sqrt($vier[2]**2/2);}
$xx1=$x1;
$xx2=$x2;
$xx3=$x3;
$xx4=$x4;
$yy1=$y1+80;
$yy2=$y2+80;
$yy3=$y3+80;
$yy4=$y4+80;
$img->line($x1,$y1,$x2,$y2,$green);
$img->line($x2,$y2,$x3,$y3,$green);
$img->line($x3,$y3,$x4,$y4,$green);
$img->line($x4,$y4,$x1,$y1,$green);
$img->line($xx1,$yy1,$xx2,$yy2,$green);
$img->line($xx2,$yy2,$xx3,$yy3,$green);
$img->line($xx3,$yy3,$xx4,$yy4,$green);
$img->line($xx4,$yy4,$xx1,$yy1,$green);
$img->line($x1,$y1,$xx1,$yy1,$green);
$img->line($x2,$y2,$xx2,$yy2,$green);
$img->line($x3,$y3,$xx3,$yy3,$green);
$img->line($x4,$y4,$xx4,$yy4,$green);
$data.=$img->gifanimadd(0,0,0,1);
if($teller<20){
$teller++;
goto again;}


$data.=$im->gifanimend;
binmode STDOUT;
print $data;
[download]

have a good day