Unable to setup: NO PNG HEADERS FOUND, you need to install libpng-dev

[canpoyrazoglu]

I'm on a fresh Ubuntu 18.10 installation (just installed on a fresh VM).

When I try to build using "./setup.py build" I get the following error:

can@ubuntu:~/Desktop/gnofract4d$ ./setup.py build
Can't find 'libpng'
Some functionality will be disabled
Traceback (most recent call last):
  File "./setup.py", line 53, in <module>
    raise Exception("NO PNG HEADERS FOUND, you need to install libpng-dev")
Exception: NO PNG HEADERS FOUND, you need to install libpng-dev

I've installed libpng:

can@ubuntu:~/Desktop/gnofract4d$ sudo apt-get install libpng-dev
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
  libpng-tools
The following NEW packages will be installed:
  libpng-dev libpng-tools
0 upgraded, 2 newly installed, 0 to remove and 21 not upgraded.
Need to get 202 kB of archives.
After this operation, 703 kB of additional disk space will be used.
Do you want to continue? [Y/n] 
Get:1 http://us.archive.ubuntu.com/ubuntu cosmic/main amd64 libpng-dev amd64 1.6.34-2 [177 kB]
Get:2 http://us.archive.ubuntu.com/ubuntu cosmic/main amd64 libpng-tools amd64 1.6.34-2 [25.6 kB]
Fetched 202 kB in 1s (169 kB/s)         
Selecting previously unselected package libpng-dev:amd64.
(Reading database ... 171360 files and directories currently installed.)
Preparing to unpack .../libpng-dev_1.6.34-2_amd64.deb ...
Unpacking libpng-dev:amd64 (1.6.34-2) ...
Selecting previously unselected package libpng-tools.
Preparing to unpack .../libpng-tools_1.6.34-2_amd64.deb ...
Unpacking libpng-tools (1.6.34-2) ...
Setting up libpng-tools (1.6.34-2) ...
Processing triggers for man-db (2.8.4-2) ...
Setting up libpng-dev:amd64 (1.6.34-2) ...

However, I'm still getting the exact same error about not finding libpng. What am I doing wrong? Why can't it find libpng after installing and why can't it build properly as readme clearly states that libpng is optional anyway?

[canpoyrazoglu]

Okay, I've solved the problem by digging into the setup script, but there are multiple issues here about incorrect documentation that needs to be corrected:

Querying about libpng and libjpeg was using pkg-config command. pkg-config was not installed in fresh Ubuntu installation, so it was failing, and thinking that libpng was not installed. The stack trace doesn't mention anything about pkg-config, nor does documentation. I've installed pkg-config

sudo apt install pkg-config

That problem went away, but I still got an error:

fract4d/c/fract4dmodule.cpp:14:10: fatal error: Python.h: No such file or directory #include "Python.h"

That one was easy, I needed to install Python 3 developer tools (though someone inexperienced might have trouble finding the cause):

sudo apt-get install python3-dev

Then, that problem went away too.
I tried to build again, then I got an error about libjpeg not being present. I've installed that too and problem went away and I could run Gnofract4.

To summarize:

• Readme should state that you need to have pkg-config
• Readme should state that you need to have python3-dev
• libpng and libjpeg are currently NOT optional. Readme should either state that they are mandatory, or make them optional.

[edyoung]

Please see if this PR addresses the issue

[canpoyrazoglu]

Yes, it addresses the issue clearly now.