CMake: Major cleanup to support find_package(raylib)

Remove that link_libraries_to_executable() hack and defines a proper
raylib target that can be used with target_link_libraries.

The same target is also available for external (user) code by using
find_package(raylib).

This results in:

- Remove hardcoded build directories from examples and games CMakeLists.txt
- Allow rlgl_standalone and other special examples to be built easily
- Allow CMake projects to find_package(raylib instead of fiddling with pkg-config
- Makes code a little more maintainable
- Fixes #471, #606.
- Makes code less confusing by removing the double use of PLATFORM (#584).

Note that this is still not _The Right Way_(TM), because normally
raylib-config.cmake (or its includes) would be automatically generated.
I didn't manage to get that to work though, so I went the easier route
of just wrapping pkg_check_modules for consumption by find_package.

5 files changed, 124 insertions, 88 deletions

diff --git a/cmake/LibraryPathToLinkerFlags.cmake b/cmake/LibraryPathToLinkerFlags.cmake
new file mode 100644
index 00000000..05942b75
--- /dev/null
+++ b/cmake/LibraryPathToLinkerFlags.cmake
@@ -0,0 +1,24 @@
+function(library_path_to_linker_flags LD_FLAGS LIB_PATHS)
+  foreach(L ${LIB_PATHS})
+    get_filename_component(DIR  ${L} PATH)
+    get_filename_component(LIBFILE ${L} NAME_WE)
+    STRING(REGEX REPLACE "^lib" "" FILE ${LIBFILE})
+
+    if (${L} MATCHES "[.]framework$")
+        set(FILE_OPT "-framework ${FILE}")
+        set(DIR_OPT  "-F${DIR}")
+    else()
+        set(FILE_OPT "-l${FILE}")
+        set(DIR_OPT  "-L${DIR}")
+    endif()
+
+    if ("${DIR}" STREQUAL "" OR "${DIR}" STREQUAL "${LASTDIR}")
+        set (DIR_OPT "")
+    endif()
+
+    set(LASTDIR ${DIR})
+
+    set(${LD_FLAGS} ${${LD_FLAGS}} ${DIR_OPT} ${FILE_OPT} PARENT_SCOPE)
+    string (REPLACE ";" " " ${LD_FLAGS} "${${LD_FLAGS}}")
+  endforeach()
+endfunction()
diff --git a/cmake/PopulateConfigVariablesLocally.cmake b/cmake/PopulateConfigVariablesLocally.cmake
new file mode 100644
index 00000000..151070ea
--- /dev/null
+++ b/cmake/PopulateConfigVariablesLocally.cmake
@@ -0,0 +1,11 @@
+macro(populate_config_variables_locally target)
+  get_property(raylib_INCLUDE_DIRS TARGET ${target} PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+  #get_property(raylib_LIBRARIES    TARGET ${target} PROPERTY LOCATION) # only works for SHARED
+  get_property(raylib_LDFLAGS      TARGET ${target} PROPERTY INTERFACE_LINK_LIBRARIES)
+  get_property(raylib_DEFINITIONS  TARGET ${target} PROPERTY DEFINITIONS)
+
+  set(raylib_INCLUDE_DIRS "${raylib_INCLUDE_DIRS}" PARENT_SCOPE)
+  #set(raylib_LIBRARIES   "${raylib_INCLUDE_DIRS}" PARENT_SCOPE)
+  set(raylib_LDFLAGS      "${raylib_LDFLAGS}" PARENT_SCOPE)
+  set(raylib_DEFINITIONS  "${raylib_DEFINITIONS}" PARENT_SCOPE)
+endmacro()
diff --git a/cmake/raylib-config-version.cmake b/cmake/raylib-config-version.cmake
new file mode 100644
index 00000000..74fd03cc
--- /dev/null
+++ b/cmake/raylib-config-version.cmake
@@ -0,0 +1,21 @@
+set(PACKAGE_VERSION "@PROJECT_VERSION@")
+
+if(PACKAGE_FIND_VERSION VERSION_EQUAL PACKAGE_VERSION)
+  set(PACKAGE_VERSION_EXACT TRUE)
+endif()
+if(NOT PACKAGE_FIND_VERSION VERSION_GREATER PACKAGE_VERSION)
+  set(PACKAGE_VERSION_COMPATIBLE TRUE)
+else(NOT PACKAGE_FIND_VERSION VERSION_GREATER PACKAGE_VERSION)
+  set(PACKAGE_VERSION_UNSUITABLE TRUE)
+endif(NOT PACKAGE_FIND_VERSION VERSION_GREATER PACKAGE_VERSION)
+
+# if the installed or the using project don't have CMAKE_SIZEOF_VOID_P set, ignore it:
+if("${CMAKE_SIZEOF_VOID_P}" STREQUAL "" OR "@CMAKE_SIZEOF_VOID_P@" STREQUAL "")
+   return()
+endif()
+
+if(NOT CMAKE_SIZEOF_VOID_P STREQUAL "@CMAKE_SIZEOF_VOID_P@")
+  math(EXPR installedBits "8 * 8")
+  set(PACKAGE_VERSION "${PACKAGE_VERSION} (${installedBits}bit)")
+  set(PACKAGE_VERSION_UNSUITABLE TRUE)
+endif()
diff --git a/cmake/raylib-config.cmake b/cmake/raylib-config.cmake
new file mode 100644
index 00000000..e2e5e9ae
--- /dev/null
+++ b/cmake/raylib-config.cmake
@@ -0,0 +1,68 @@
+# - Try to find raylib
+# Options:
+#   raylib_USE_STATIC_LIBS - OFF by default
+#   raylib_VERBOSE         - OFF by default
+# Once done, this defines a raylib target that can be passed to
+# target_link_libraries as well as following variables:
+#
+#   raylib_FOUND - System has raylib installed
+#   raylib_INCLUDE_DIRS - The include directories for the raylib header(s)
+#   raylib_LIBRARIES - The libraries needed to use raylib
+#   raylib_LDFLAGS - The linker flags needed with raylib
+#   raylib_DEFINITIONS - Compiler switches required for using raylib
+
+set(XPREFIX PC_RAYLIB)
+if (raylib_USE_STATIC_LIBS)
+    set(XPREFIX ${XPREFIX}_STATIC)
+endif()
+
+find_package(PkgConfig)
+pkg_check_modules(${XPREFIX} REQUIRED raylib)
+set(raylib_DEFINITIONS ${${XPREFIX}_CFLAGS})
+
+find_path(raylib_INCLUDE_DIR
+    NAMES raylib.h
+    HINTS ${${XPREFIX}_INCLUDE_DIRS}
+)
+
+find_library(raylib_LIBRARY
+    NAMES raylib
+    HINTS ${${XPREFIX}_LIBRARY_DIRS}
+)
+
+set(raylib_LIBRARIES    ${raylib_LIBRARY})
+set(raylib_LIBRARY_DIRS ${${XPREFIX}_LIBRARY_DIRS})
+set(raylib_LIBRARY_DIR  ${raylib_LIBRARY_DIRS})
+set(raylib_INCLUDE_DIRS ${raylib_INCLUDE_DIR})
+set(raylib_LDFLAGS      ${${XPREFIX}_LDFLAGS})
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(raylib DEFAULT_MSG
+    raylib_LIBRARY
+    raylib_INCLUDE_DIR
+)
+
+mark_as_advanced(raylib_LIBRARY raylib_INCLUDE_DIR)
+
+if (raylib_USE_STATIC_LIBS)
+  add_library(raylib STATIC IMPORTED GLOBAL)
+else()
+  add_library(raylib SHARED IMPORTED GLOBAL)
+endif()
+string (REPLACE ";" " " raylib_LDFLAGS "${raylib_LDFLAGS}")
+
+set_target_properties(raylib
+  PROPERTIES
+  IMPORTED_LOCATION             "${raylib_LIBRARIES}"
+  INTERFACE_INCLUDE_DIRECTORIES "${raylib_INCLUDE_DIRS}"
+  INTERFACE_LINK_LIBRARIES      "${raylib_LDFLAGS}"
+  INTERFACE_COMPILE_OPTIONS     "${raylib_DEFINITIONS}"
+)
+
+if (raylib_VERBOSE)
+  message(STATUS "raylib_FOUND: ${raylib_FOUND}")
+  message(STATUS "raylib_INCLUDE_DIRS: ${raylib_INCLUDE_DIRS}")
+  message(STATUS "raylib_LIBRARIES: ${raylib_LIBRARIES}")
+  message(STATUS "raylib_LDFLAGS: ${raylib_LDFLAGS}")
+  message(STATUS "raylib_DEFINITIONS: ${raylib_DEFINITIONS}")
+endif()
diff --git a/cmake/utils.cmake b/cmake/utils.cmake
deleted file mode 100644
index 57829407..00000000
--- a/cmake/utils.cmake
+++ /dev/null
@@ -1,88 +0,0 @@
-# All sorts of things that we need cross project
-cmake_minimum_required(VERSION 2.8.0)
-
-add_definitions("-DRAYLIB_CMAKE=1")
-
-if (${USE_OPENAL_BACKEND})
-  find_package(OpenAL REQUIRED)
-endif()
-
-if(${PLATFORM} MATCHES "Android")
-  find_library(OPENGL_LIBRARY OpenGL)
-  set(LIBS_PRIVATE m log android EGL GLESv2 OpenSLES atomic c)
-elseif(${PLATFORM} MATCHES "Web")
-elseif(APPLE)
-  find_library(OPENGL_LIBRARY OpenGL)
-
-  set(LIBS_PRIVATE ${OPENGL_LIBRARY})
-elseif(WIN32)
-  # no pkg-config --static on Windows yet...
-else()
-  find_library(pthread NAMES pthread)
-  find_package(OpenGL QUIET)
-  if ("${OPENGL_LIBRARIES}" STREQUAL "")
-    set(OPENGL_LIBRARIES "GL")
-  endif()
-
-  if ("${CMAKE_SYSTEM_NAME}" MATCHES "(Net|Open)BSD")
-    find_library(OSS_LIBRARY ossaudio)
-  endif()
-
-  set(LIBS_PRIVATE m pthread ${OPENGL_LIBRARIES} ${OSS_LIBRARY})
-endif()
-
-include_directories(${OPENGL_INCLUDE_DIR} ${OPENAL_INCLUDE_DIR})
-set(LIBS_PRIVATE ${LIBS_PRIVATE} ${OPENAL_LIBRARY})
-
-if(${PLATFORM} MATCHES "Desktop")
-  if(USE_EXTERNAL_GLFW STREQUAL "ON")
-    find_package(glfw3 3.2.1 REQUIRED)
-  elseif(USE_EXTERNAL_GLFW STREQUAL "IF_POSSIBLE")
-    find_package(glfw3 3.2.1 QUIET)
-  endif()
-  if (glfw3_FOUND)
-    set(LIBS_PRIVATE ${LIBS_PRIVATE} glfw)
-  endif()
-endif()
-
-if(CMAKE_SYSTEM_NAME STREQUAL Linux)
-  set(LINUX TRUE)
-endif()
-
-foreach(L ${LIBS_PRIVATE})
-  get_filename_component(DIR  ${L} PATH)
-  get_filename_component(LIBFILE ${L} NAME_WE)
-  STRING(REGEX REPLACE "^lib" "" FILE ${LIBFILE})
-
-  if (${L} MATCHES "[.]framework$")
-      set(FILE_OPT "-framework ${FILE}")
-      set(DIR_OPT  "-F${DIR}")
-  else()
-      set(FILE_OPT "-l${FILE}")
-      set(DIR_OPT  "-L${DIR}")
-  endif()
-
-  if ("${DIR}" STREQUAL "" OR "${DIR}" STREQUAL "${LASTDIR}")
-      set (DIR_OPT "")
-  endif()
-
-  set(LASTDIR ${DIR})
-
-  set(__PKG_CONFIG_LIBS_PRIVATE ${__PKG_CONFIG_LIBS_PRIVATE} ${DIR_OPT} ${FILE_OPT})
-  string (REPLACE ";" " " __PKG_CONFIG_LIBS_PRIVATE "${__PKG_CONFIG_LIBS_PRIVATE}")
-endforeach(L)
-
-
-
-# Do the linking for executables that are meant to link raylib
-function(link_libraries_to_executable executable)
-  # Link raylib
-  if (TARGET raylib_shared)
-    target_link_libraries(${executable} raylib_shared)
-  elseif(${PLATFORM} MATCHES "Web")
-    target_link_libraries(${executable} ${__PKG_CONFIG_LIBS_PRIVATE})
-    target_link_libraries(${executable} raylib)
-  else()
-    target_link_libraries(${executable} raylib ${__PKG_CONFIG_LIBS_PRIVATE})
-  endif()
-endfunction()