NOTE: This is using the latest version of SDL_image (1.2.11) from Mercurial.

The configure script for SDL_image fails to detect libpng if a –build argument is specified for i386.

Repro Steps:

- get libpng-1.5.5.tar.gz from http://www.libpng.org/pub/png/libpng.html

- compile libpng from i386

	open console window and cd to libpng source folder
	./configure –build=i386-apple-darwin10.8.0
	make CFLAGS="-arch i386" LDFLAGS="-arch i386"
	make install
	lipo –info /usr/local/lib/libpng.dylib
	Non-fat file: /usr/local/lib/libpng.dylib is architecture: i386

- then, configure SDL_image

	cd _SDL_image_1.2.11
	./configure –build=i386-apple-darwin10 –disable-sdltest

> BUG: 

	configure: WARNING: *** Unable to find PNG library (http://www.libpng.org/pub/png/libpng.html)
	configure: WARNING: PNG image loading disabled

However, if you compile libpng without the –build argument (i.e. building for x86_64) :

	./configure
	make
	make install

And then invoke SDL_image's configure script without the –build argument, then the libpng library is found:

	./configure –disable-sdltest

The work-around is to invoke SDL_image's configure script *with* the i386 build argument, and then modify the Makefile to add the missing info to the DEFS entry:

	-DLOAD_PNG=1
	-DLOAD_PNG_DYNAMIC="\libpng.dylib\"

I hope this helps!

Regards,
Alain