use cmake built-in FindOpenGL module for GLES with cmake 3.23+

Author: mbaetgen-wup

CMakeLists.txt

@@ -169,8 +169,10 @@ else()
             message(FATAL_ERROR "OpenGL ES 3 support is currently only available for Linux platforms. You're building for ${CMAKE_SYSTEM_NAME}.")
         endif()
 
-        # We use a local find script for OpenGL::GLES3 until the proposed changes are merged upstream.
-        list(APPEND CMAKE_MODULE_PATH "${PROJECTM_SOURCE_DIR}/cmake/gles")
+        if (CMAKE_VERSION VERSION_LESS_EQUAL "3.26" OR CMAKE_SYSTEM_NAME STREQUAL Android)
+            # We use a local find script for OpenGL::GLES3 until the proposed changes are merged upstream.
+            list(APPEND CMAKE_MODULE_PATH "${PROJECTM_SOURCE_DIR}/cmake/gles")
+        endif()
         find_package(OpenGL REQUIRED COMPONENTS GLES3)
         if(NOT TARGET OpenGL::GLES3)
             message(FATAL_ERROR "No suitable GLES3 library was found.")

cmake/gles/README.md

@@ -1,7 +1,7 @@
 # GLES3 Find Script
 
 The OpenGL CMake find script in this directory contains additional code to find GLES versions 1 to 3. It was taken from
-CMake 3.22 and patched accordingly. A merge request is underway upstream, so ideally, this will be part of CMake 3.23+.
+CMake 3.22 and patched accordingly. A merge request was accepted upstream, it is part of CMake 3.27.
 
-In the meantime, we'll use this script as a local copy if GLES3 support is requested. Will add a version check once it's
-in upstream CMake so this file will only be used if the CMake version used to build projectM is too low.
+We use this script for CMake lower than 3.27 as a local copy if GLES3 support is requested to provide compatibility. A version check 
+compares the current CMake version so this file will only be used if the CMake version used to build projectM is too low.

src/libprojectM/projectM4Config.cmake.in

@@ -6,8 +6,14 @@ include(CMakeFindDependencyMacro)
 
 if(NOT "@ENABLE_EMSCRIPTEN@") # ENABLE_EMSCRIPTEN
     if("@ENABLE_GLES@") # ENABLE_GLES
-        list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}")
-        find_dependency(OpenGL COMPONENTS GLES3)
+        if (CMAKE_VERSION VERSION_LESS_EQUAL "3.26" OR CMAKE_SYSTEM_NAME STREQUAL Android)
+          set(PROJECTM4_PREV_MODULE_PATH ${CMAKE_MODULE_PATH})
+          list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}")
+          find_dependency(OpenGL COMPONENTS GLES3)
+          set(CMAKE_MODULE_PATH ${PROJECTM4_PREV_MODULE_PATH})
+        else()
+          find_dependency(OpenGL COMPONENTS GLES3)
+        endif()
     else()
         find_dependency(OpenGL)
     endif()