add pkg-config support. (#174)

CMakeLists.txt

@@ -68,6 +68,20 @@ install(FILES
     ${CMAKE_CURRENT_BINARY_DIR}/${PACKAGE_NAME}-config-version.cmake
   DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/${PACKAGE_NAME})
 
+# Create pkg-config file
+include(build/JoinPaths.cmake)
+# from: https://github.com/jtojnar/cmake-snips#concatenating-paths-when-building-pkg-config-files
+join_paths(DIRECTXMATH_INCLUDEDIR_FOR_PKG_CONFIG "\${prefix}" "${CMAKE_INSTALL_INCLUDEDIR}")
+join_paths(DIRECTXMATH_LIBDIR_FOR_PKG_CONFIG "\${prefix}"     "${CMAKE_INSTALL_LIBDIR}")
+
+configure_file(
+    "${CMAKE_CURRENT_SOURCE_DIR}/build/DirectXMath.pc.in"
+    "${CMAKE_CURRENT_BINARY_DIR}/DirectXMath.pc" @ONLY)
+
+# Install the pkg-config file
+install(FILES "${CMAKE_CURRENT_BINARY_DIR}/DirectXMath.pc"
+        DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
+
 #--- Test suite
 if (DEFINED VCPKG_TARGET_ARCHITECTURE)
     set(DXMATH_ARCHITECTURE ${VCPKG_TARGET_ARCHITECTURE})

build/DirectXMath.pc.in

@@ -0,0 +1,10 @@
+prefix=@CMAKE_INSTALL_PREFIX@
+libdir=@DIRECTXMATH_LIBDIR_FOR_PKG_CONFIG@
+includedir=@DIRECTXMATH_INCLUDEDIR_FOR_PKG_CONFIG@
+
+Name: @PROJECT_NAME@
+Description: @PROJECT_DESCRIPTION@
+URL: @PROJECT_HOMEPAGE_URL@
+Version: @PROJECT_VERSION@
+Cflags: -I${includedir}
+Libs:

build/JoinPaths.cmake

@@ -0,0 +1,23 @@
+# This module provides function for joining paths
+# known from most languages
+#
+# SPDX-License-Identifier: (MIT OR CC0-1.0)
+# Copyright 2020 Jan Tojnar
+# https://github.com/jtojnar/cmake-snips
+#
+# Modelled after Python’s os.path.join
+# https://docs.python.org/3.7/library/os.path.html#os.path.join
+# Windows not supported
+function(join_paths joined_path first_path_segment)
+    set(temp_path "${first_path_segment}")
+    foreach(current_segment IN LISTS ARGN)
+        if(NOT ("${current_segment}" STREQUAL ""))
+            if(IS_ABSOLUTE "${current_segment}")
+                set(temp_path "${current_segment}")
+            else()
+                set(temp_path "${temp_path}/${current_segment}")
+            endif()
+        endif()
+    endforeach()
+    set(${joined_path} "${temp_path}" PARENT_SCOPE)
+endfunction()