From 7aa72a163376336dfa100101bd329a9915144ddc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20K=C3=BCndig?= <christian@kuendig.info>
Date: Sat, 27 Jan 2024 22:33:40 +0100
Subject: [PATCH] EMSCRIPTEN: OPENGL: Disable GLAD

---
 configure                        | 4 ++--
 graphics/opengl/debug.cpp        | 9 +++++++++
 graphics/opengl/system_headers.h | 8 ++++++++
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 0ebf8e9b470..50aa26c3403 100755
--- a/configure
+++ b/configure
@@ -6351,6 +6351,7 @@ if test "$_opengl_mode" != none ; then
 		sdl)
 			# This case is for pure SDL backend. Many platforms overload it and create a new backend
 			# They still make use of SDL but it's handled below in the default case
+			_opengl_glad=yes
 			case $_sdlversion in
 				1.2.*)
 					# Stock SDL 1.2 only supports OpenGL contexts.
@@ -6367,7 +6368,7 @@ if test "$_opengl_mode" != none ; then
 							;;
 						emscripten)
 							_opengl_mode=gles2
-							_opengl_glad=no
+							_opengl_glad=no # https://github.com/Dav1dde/glad-web/issues/12
 							append_var OPENGL_LIBS "-s FULL_ES2=1 -s MAX_WEBGL_VERSION=1"
 							;;
 						*)
@@ -6377,7 +6378,6 @@ if test "$_opengl_mode" != none ; then
 					esac
 					;;
 			esac
-			_opengl_glad=yes
 			;;
 		switch)
 			_opengl_mode=gles2
diff --git a/graphics/opengl/debug.cpp b/graphics/opengl/debug.cpp
index c5273cb7bb4..6b0d95278b4 100644
--- a/graphics/opengl/debug.cpp
+++ b/graphics/opengl/debug.cpp
@@ -39,10 +39,19 @@ Common::String getGLErrStr(GLenum error) {
 		return "GL_INVALID_VALUE";
 	case GL_INVALID_OPERATION:
 		return "GL_INVALID_OPERATION";
+// OpenGL ES 2.0 doesn't have GL_STACK_OVERFLOW and GL_STACK_UNDERFLOW
+// see https://registry.khronos.org/OpenGL/api/GLES2/gl2.h and https://registry.khronos.org/OpenGL/api/GLES2/gl2ext.h
+#ifdef USE_FORCED_GLES2
+	case GL_STACK_OVERFLOW_KHR:
+		return "GL_STACK_OVERFLOW_KHR";
+	case GL_STACK_UNDERFLOW_KHR:
+		return "GL_STACK_UNDERFLOW_KHR";
+#else
 	case GL_STACK_OVERFLOW:
 		return "GL_STACK_OVERFLOW";
 	case GL_STACK_UNDERFLOW:
 		return "GL_STACK_UNDERFLOW";
+#endif
 	case GL_OUT_OF_MEMORY:
 		return "GL_OUT_OF_MEMORY";
 	default:
diff --git a/graphics/opengl/system_headers.h b/graphics/opengl/system_headers.h
index f26fc141b5f..145b38221d7 100644
--- a/graphics/opengl/system_headers.h
+++ b/graphics/opengl/system_headers.h
@@ -84,6 +84,14 @@
 		#define GL_MAX_SAMPLES 0x8D57
 	#endif
 
+	#if !defined(GL_STACK_OVERFLOW_KHR)
+		#define GL_STACK_OVERFLOW_KHR 0x0503
+	#endif
+
+	#if !defined(GL_STACK_UNDERFLOW_KHR)
+		#define GL_STACK_UNDERFLOW_KHR 0x0504
+	#endif
+
 #elif USE_FORCED_GLES
 
 	#define GL_GLEXT_PROTOTYPES