From c879308ad65712a6415d544e11d1cb585b372cf4 Mon Sep 17 00:00:00 2001
From: s0600204 <s0600204@wildfiregames.com>
Date: Wed, 3 Mar 2021 16:11:41 +0000
Subject: [PATCH] Use pkgconfig to find libpng

Should hopefully resolve an issue raised on IRC by @spcman and @Xavi92

Reviewed By: wraitii
Differential Revision: https://code.wildfiregames.com/D3610
This was SVN commit r24998.
---
 build/premake/extern_libs5.lua        | 23 +++++++++++------------
 build/workspaces/update-workspaces.sh |  1 +
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/build/premake/extern_libs5.lua b/build/premake/extern_libs5.lua
index 275438bd39..51820b70cc 100644
--- a/build/premake/extern_libs5.lua
+++ b/build/premake/extern_libs5.lua
@@ -411,24 +411,23 @@ extern_lib_defs = {
 	},
 	libpng = {
 		compile_settings = function()
-			if os.istarget("windows") or os.istarget("macosx") then
+			if os.istarget("windows") then
 				add_default_include_paths("libpng")
-			end
-			if os.getversion().description == "OpenBSD" then
-				sysincludedirs { "/usr/local/include/libpng" }
+			else
+				-- Support LIBPNG_CONFIG for overriding the default (pkg-config --cflags libpng)
+				-- i.e. on OSX where it gets set in update-workspaces.sh
+				pkgconfig.add_includes("libpng", os.getenv("LIBPNG_CONFIG"))
 			end
 		end,
 		link_settings = function()
-			if os.istarget("windows") or os.istarget("macosx") then
+			if os.istarget("windows") then
 				add_default_lib_paths("libpng")
+				add_default_links({
+					win_names  = { "libpng16" },
+				})
+			else
+				pkgconfig.add_links("libpng", os.getenv("LIBPNG_CONFIG"), "--ldflags")
 			end
-			add_default_links({
-				win_names  = { "libpng16" },
-				unix_names = { "png" },
-				-- Otherwise ld will sometimes pull in ancient 1.2 from the SDK, which breaks the build :/
-				-- TODO: Figure out why that happens
-				osx_names = { "png16" },
-			})
 		end,
 	},
 	libsodium = {
diff --git a/build/workspaces/update-workspaces.sh b/build/workspaces/update-workspaces.sh
index 36848e0c19..e266660077 100755
--- a/build/workspaces/update-workspaces.sh
+++ b/build/workspaces/update-workspaces.sh
@@ -73,6 +73,7 @@ if [ "`uname -s`" = "Darwin" ]; then
   # Set *_CONFIG variables on OS X, to override the path to e.g. sdl2-config
   export GLOOX_CONFIG=${GLOOX_CONFIG:="$(pwd)/../../libraries/osx/gloox/bin/gloox-config"}
   export ICU_CONFIG=${ICU_CONFIG:="$(pwd)/../../libraries/osx/icu/bin/icu-config"}
+  export LIBPNG_CONFIG=${PNG_CONFIG:="$(pwd)/../../libraries/osx/libpng/bin/libpng-config"}
   export SDL2_CONFIG=${SDL2_CONFIG:="$(pwd)/../../libraries/osx/sdl2/bin/sdl2-config"}
   export WX_CONFIG=${WX_CONFIG:="$(pwd)/../../libraries/osx/wxwidgets/bin/wx-config"}
   export XML2_CONFIG=${XML2_CONFIG:="$(pwd)/../../libraries/osx/libxml2/bin/xml2-config"}