From 38929651cd2a8f7eddda3c315786667a49bda8a6 Mon Sep 17 00:00:00 2001
From: Manuel Alfayate Corchete <redwindwanderer@gmail.com>
Date: Tue, 30 Jan 2024 03:16:59 +0100
Subject: [PATCH] Fix OpenGL_ES support on GNU/Linux. (#415)

* Fix OpenGL_ES support on GNU/Linux.

* Use -lGLESv3 on Android only, and -lGLESv2 on other Linux based systems.
---
 extern/CMakeLists.txt | 7 ++++++-
 src/CMakeLists.txt    | 9 +++++++--
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/extern/CMakeLists.txt b/extern/CMakeLists.txt
index d0e931e11..2bab4b3f6 100644
--- a/extern/CMakeLists.txt
+++ b/extern/CMakeLists.txt
@@ -119,7 +119,12 @@ elseif (CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     )
 elseif (CMAKE_SYSTEM_NAME STREQUAL "Linux")
     find_package(GLEW REQUIRED)
-    target_link_libraries(ImGui PUBLIC ${OPENGL_glx_LIBRARY} ${OPENGL_opengl_LIBRARY} GLEW::GLEW)
+    if (DEFINED USE_OPENGLES)
+        target_link_libraries(ImGui PUBLIC ${OPENGL_GLESv2_LIBRARY} GLEW::GLEW)
+        add_compile_definitions(IMGUI_IMPL_OPENGL_ES3)
+    else()
+        target_link_libraries(ImGui PUBLIC ${OPENGL_glx_LIBRARY} ${OPENGL_opengl_LIBRARY} GLEW::GLEW)
+    endif()
 endif()
 
 #=================== tinyxml2 ===================
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 85d8b43fd..02c826e50 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -473,8 +473,13 @@ if (CMAKE_SYSTEM_NAME STREQUAL "Linux")
 endif()
 
 if (USE_OPENGLES)
-    find_library(OPENGLES_LIBRARY GLESv3)
-    target_link_libraries(libultraship PRIVATE GLESv3)
+    if (CMAKE_SYSTEM_NAME STREQUAL "Android")
+        find_library(OPENGLES_LIBRARY GLESv3)
+        target_link_libraries(libultraship PRIVATE GLESv3)
+    else()
+        find_library(OPENGLES_LIBRARY GLESv2)
+        target_link_libraries(libultraship PRIVATE GLESv2)
+    endif()
 endif()
 
 #=================== Compile Options & Defs ===================