[vtkusers] How to build libraries for both 32-bit and 64-bit architectures

[Michael Jackson]

You need to pass -arch i386 -arch x86_64 to the compiler. Usually in  
the configure step you can add more compile flags. By passing both of  
those arguments the compiler will compile a 32/64 bit universal binary  
of the library. When something else links to the libpng, the linking  
program only cares that linpng has _at least_ the archs that it is  
compiling for. Any extras are just ignored.

Follow?

Mike Jackson

On Sep 27, 2008, at 1:13 PM, Elvis Dowson wrote:

> Hi,
>        I've just run into a bit of problem with building some  
> dependent libraries.
>
> Here is my situation, I have libpng-1.2.31 which is used by  
> paraview-3.x.x, vtk-5.x and qt-4.5.x.
>
> For paraview, I need the 32-bit version of libpng.
>
> For qt-4.5.x 64-bit, vtk-5.3.x 64-bit and to use the Cocoa  
> framework, I need a 64-bit version of libpng.
>
> I first built paraview with the 32-bit version of libpng, and it ran  
> correctly.
>
> Then for my qt-4.5.x and vtk-5.x 64-bit compilation tests, I was  
> forced to rebuild and install the 64-bit version of libpng. When i  
> ran sudo make install, it copied the 64-bit version of the libraries  
> and paraview stopped working.
>
> Could someone please tell me what I should do to manage a libpng  
> installation that can support both 32-bit and 64-bit architectures?
>
> When I run ./configure --help I get the following information:
>
> Installation directories:
>  --prefix=PREFIX         install architecture-independent files in  
> PREFIX
>                          [/usr/local]
>  --exec-prefix=EPREFIX   install architecture-dependent files in  
> EPREFIX
>                          [PREFIX]
>
> What is the --exec-prefix for ?
>
> Best regards,
>
> Elvis Dowson