chore: add eigen library for vector math

.gitmodules

@@ -13,3 +13,6 @@
 [submodule "thirdparty/json"]
 	path = thirdparty/json
 	url = https://github.com/nlohmann/json.git
+[submodule "thirdparty/eigen"]
+	path = thirdparty/eigen
+	url = https://gitlab.com/libeigen/eigen.git

premake5.lua

@@ -84,6 +84,7 @@ workspace "OpenAssetTools"
 -- ThirdParty
 -- ========================
 include "thirdparty/catch2.lua"
+include "thirdparty/eigen.lua"
 include "thirdparty/libtomcrypt.lua"
 include "thirdparty/libtommath.lua"
 include "thirdparty/json.lua"
@@ -95,6 +96,7 @@ include "thirdparty/zlib.lua"
 -- ThirdParty group: All projects that are external dependencies
 group "ThirdParty"
     catch2:project()
+    eigen:project()
     libtommath:project()
     libtomcrypt:project()
     json:project()

src/ObjWriting.lua

@@ -55,6 +55,7 @@ function ObjWriting:project()
 		Utils:include(includes)
 		minilzo:include(includes)
 		minizip:include(includes)
+		eigen:include(includes)
 		json:include(includes)
 		libtomcrypt:include(includes)
 

thirdparty/eigen

@@ -0,0 +1 @@
+Subproject commit afb17288cbb5bac779a850e3ec6ba106b7f42c1c

thirdparty/eigen.lua

@@ -0,0 +1,23 @@
+eigen = {}
+
+function eigen:include(includes)
+	if includes:handle(self:name()) then
+		includedirs {
+			path.join(ThirdPartyFolder(), "eigen", "Eigen")
+		}
+	end
+end
+
+function eigen:link()
+end
+
+function eigen:use()
+	
+end
+
+function eigen:name()
+    return "eigen"
+end
+
+function eigen:project()
+end