From 834c79da2cf06a687af648da1162f2ae5afa01fa Mon Sep 17 00:00:00 2001
From: Nanley Chery <nanley.g.chery@intel.com>
Date: Tue, 9 Aug 2022 11:16:55 -0700
Subject: [PATCH] Set the version of the BC3 shaders to 310 es

The shaders are compatible with GLSL ES version 310. Require the
GL_ARB_ES3_1_compatibility extension and change the version directives
accordingly so that we get validation from the GL implementation.
---
 bin/Data/bc1.glsl              | 2 +-
 bin/Data/bc1_dither.glsl       | 2 +-
 bin/Data/bc4.glsl              | 2 +-
 bin/Data/etc2_rgba_stitch.glsl | 2 +-
 src/PlatformGL.cpp             | 8 ++++++++
 5 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/bin/Data/bc1.glsl b/bin/Data/bc1.glsl
index 51e82c9..e796602 100644
--- a/bin/Data/bc1.glsl
+++ b/bin/Data/bc1.glsl
@@ -1,4 +1,4 @@
-#version 430 core
+#version 310 es
 
 #if defined(GL_ES) && GL_ES == 1
 	// Desktop GLSL allows the const keyword for either compile-time or
diff --git a/bin/Data/bc1_dither.glsl b/bin/Data/bc1_dither.glsl
index 4ca239f..f4c011f 100644
--- a/bin/Data/bc1_dither.glsl
+++ b/bin/Data/bc1_dither.glsl
@@ -1,4 +1,4 @@
-#version 430 core
+#version 310 es
 
 #define BC1_DITHER
 #include "bc1.glsl"
diff --git a/bin/Data/bc4.glsl b/bin/Data/bc4.glsl
index 7cd6cbf..70bc599 100644
--- a/bin/Data/bc4.glsl
+++ b/bin/Data/bc4.glsl
@@ -1,4 +1,4 @@
-#version 430 core
+#version 310 es
 
 #if defined(GL_ES) && GL_ES == 1
 	// Desktop GLSL allows the const keyword for either compile-time or
diff --git a/bin/Data/etc2_rgba_stitch.glsl b/bin/Data/etc2_rgba_stitch.glsl
index 33b0923..d06d0f2 100644
--- a/bin/Data/etc2_rgba_stitch.glsl
+++ b/bin/Data/etc2_rgba_stitch.glsl
@@ -2,7 +2,7 @@
 // This compute shader merely stitches them together to form the final result
 // It's also used by RG11 driver to stitch two R11 into one RG11
 
-#version 430 core
+#version 310 es
 
 // #include "/media/matias/Datos/SyntaxHighlightingMisc.h"
 
diff --git a/src/PlatformGL.cpp b/src/PlatformGL.cpp
index 96ffa00..b91b8ac 100644
--- a/src/PlatformGL.cpp
+++ b/src/PlatformGL.cpp
@@ -69,12 +69,20 @@ namespace betsy
 
 		g_glContext = SDL_GL_CreateContext( g_sdlWindow );
 
+		const SDL_bool has_required_extensions = SDL_GL_ExtensionSupported( "GL_ARB_ES3_1_compatibility" );
+
 		if( !g_glContext )
 		{
 			fprintf( stderr, "GL Context creation failed.\n" );
 			SDL_Quit();
 			abort();
 		}
+		else if ( has_required_extensions == SDL_FALSE )
+		{
+			fprintf( stderr, "GL Context lacks required extensions.\n" );
+			SDL_Quit();
+			abort();
+		}
 		else
 		{
 			printf( "GL Context creation suceeded.\n" );