在非常高的图像上使用PHP绘制线条，脚本停止绘制。 怎么了，怎么解决？

Question

I have a PHP script that creates a very tall image and draws a lot of lines on it (an organizational web kind of look). For the tallest images I've tried creating, the line drawing just stops abruptly toward the middle to bottom of the image: http://i.imgur.com/4Plgr.png

I ran into this problem using imagecreate(), then I found out that imagecreatetruecolor() can handle larger images, so I switched to that. I'm still having the same problem, but the script can now handle somewhat larger images. I think it should be drawing about 1200 lines. The script doesn't take more than 3 seconds to execute. Here's an image that executed completely: http://i.imgur.com/PaXrs.png

I adjusted the memory limits with ini_set('memory_limit', '1000M') but my scripts never reach near the limit.

How do I force the script to keep drawing until it finishes? Or how can I use PHP to create an image using less memory (which I think is the problem)?

if(sizeof($array[0])<300)
$image=imagecreate($width,$height);
else
$image=imagecreatetruecolor($width,$height);
imagefill($image,0,0,imagecolorallocate($image,255,255,255));
for($p=0; $p<sizeof($linepoints); $p++){
$posx1=77+177*$linepoints[$p][0];
$posy1=-4+46*$linepoints[$p][1];
$posx2=77+177*$linepoints[$p][2];
$posy2=-4+46*$linepoints[$p][3];
$image=draw_trail($image,$posx1,$posy1,$posx2,$posy2);
}
imagepng($image,"images/table_backgrounds/table_background".$tsn.".png",9);
imagedestroy($image);

function draw_trail($image,$posx1,$posy1,$posx2,$posy2){
$black=imagecolorallocate($image,0,0,0);
if($posy1==$posy2)
imageline($image,$posx1,$posy1,$posx2,$posy2,$black);
else{
imageline($image,$posx1,$posy1,$posx1+89,$posy1,$black);
imageline($image,$posx1+89,$posy1,$posx1+89,$posy2,$black);
imageline($image,$posx1+89,$posy2,$posx2,$posy2,$black);
}
return $image;
}

Answer 1

OP here. I figured out, or at least got around, my problem. I was drawing a lot of lines on the image, and the way my code got those points created a lot of repeats, so I still suspect it was a memory problem. I consolidated all the points, taking out the repeats and now it works just fine. Thanks to anyone that tried to help.