Transparency Issue

barkerja

Hey guys,

Alright. I don't have too much experience with GD but I've done a little research and heard that there is some sort of transparency bug in the current version of GD and this may be my problem, I don't know.

First off, I'll start off with the script. I have three images, merging all of them together. Two of them have transparency. The script itself takes the main image, a compass, and overlays two others.. a runway and an arrow indicating wind direction. Everything is fine transparency wise until I rotate the runway or wind arrow images then all is haywire.

You can demo the script here: http://demo.inspiredmind.net/wind_reference/index.php?wind=0&runway=0

Change the parameters to whatever you want (0-359) and notice the sometimes different results. You can also view the code at http://demo.inspiredmind.net/wind_reference/source.php.

I'm lost so ANY help is greatly appreciated.

Weedpacket

I think it's because you're using GIF and palette-based images which have limited transparency support anyway, rather than PNG. Like the manual says about imagecolortransparent,

Note: Transparency is copied only with imagecopymerge() and true color images, not with imagecopy() or pallete images.

You'd get further using PNG elements and copying them into a truecolour image - even if you insist on converting it into a palette-based GIF at the end for some reason.

barkerja

I made a few changes, but seems to stay the same.

I just noticed the gray image that is copied seems to be fine, could maybe be fine tuned a little better but it seems to merge transparently fine. But the black image on the other hand seems to be rather messed up, especially when you rotate it at different angles.