PNG textures rendered plain white with libpng16

[illwieckz]

That's a bug I noticed a long time ago, but I did not find time to report it before.

At some point in the past years, PNG textures started to be rendered white. Other formats like TGA are not affected.

See how it looks:

The bug may have started to be seen on my end when my system stopped to build GtkRadiant against libpng12 and started to build it against libpng16.

Speaking about libpng and radiant, it is known NetRadiant faced several issues related to the libpng 12 to 16 transition because of libpng shipping an implementation of zlib that may conflict with the standalone zlib used by radiant.

[TTimo]

That link doesn't work for me btw.

[ensiform]

Alternatively could use something not requiring libpng unless write png is needed. ioquake3 engine has a simple png reader that doesn't need any libs. Stb probably also has a basic one too.

https://github.com/ioquake/ioq3/blob/master/code/renderercommon/tr_image_png.c

[illwieckz]

I fixed the link.