From 576a7cda0d88d77b8bfd7a4e1127bf06b36edd78 Mon Sep 17 00:00:00 2001
From: Manuel Alfayate Corchete <redwindwanderer@gmail.com>
Date: Sat, 1 Feb 2020 20:27:47 +0100
Subject: [PATCH] Fix SDL2 with GLES2 compilation (#235)

---
 src/gapi/gl.h | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/gapi/gl.h b/src/gapi/gl.h
index 0581f4e..33c3b7a 100644
--- a/src/gapi/gl.h
+++ b/src/gapi/gl.h
@@ -66,7 +66,6 @@
     #include <SDL2/SDL.h>
 
     #if defined(_GAPI_GLES)
-        #define GL_GLEXT_PROTOTYPES 1
         #include <SDL2/SDL_opengles2.h>
         #include <SDL2/SDL_opengles2_gl2ext.h>
 
@@ -94,6 +93,8 @@
         #define GL_TEXTURE_WRAP_R       0
         #define GL_DEPTH_STENCIL        GL_DEPTH_STENCIL_OES
         #define GL_UNSIGNED_INT_24_8    GL_UNSIGNED_INT_24_8_OES
+	//We need this on GLES2, too.
+        #define GL_TEXTURE_MAX_LEVEL     GL_TEXTURE_MAX_LEVEL_APPLE
 
         #define glTexImage3D(...) 0
         #ifndef GL_TEXTURE_3D // WUUUUUT!?
@@ -108,7 +109,6 @@
         #define glGetProgramBinary(...)
         #define glProgramBinary(...)
     #else
-        #define GL_GLEXT_PROTOTYPES 1
         #include <SDL2/SDL_opengl.h>
         #include <SDL2/SDL_opengl_glext.h>
     #endif
@@ -1483,7 +1483,9 @@ namespace GAPI {
             if (count) {
                 #ifdef _OS_ANDROID
                     glInvalidateFramebuffer(GL_FRAMEBUFFER, count, discard);
-                #else
+                #elif !defined(__SDL2__)
+                    /* SDL2 typically uses MESA which does not have glDiscardFramebufferEXT() implemented
+                       for some drivers, like Gallium VC4. */ 
                     glDiscardFramebufferEXT(GL_FRAMEBUFFER, count, discard);
                 #endif
             }