Why when i rotate the image black borders appear? PHP GD

Answer 1

Looks like the default color of your image is white:

$source=imagecreatetruecolor(100, 100);
imagefilledrectangle($source, 0, 0, 100, 100, $white);

And your transparency is black:

imagecolortransparent($asd, $black);

Try making the transparency white.