From ce79649c02edd1e167815cfc72e4c3b986237894 Mon Sep 17 00:00:00 2001
From: "Unknown W. Brackets" <checkins@unknownbrackets.org>
Date: Sat, 8 Oct 2022 16:06:39 -0700
Subject: [PATCH] GLES: Use GL_LUMINANCE on GLES for indexed tex.

See #16176, used for rendered CLUTs.
---
 Common/GPU/D3D9/D3D9StateCache.h   | 12 ------------
 Common/GPU/OpenGL/DataFormatGL.cpp | 13 +++++++++++--
 2 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/Common/GPU/D3D9/D3D9StateCache.h b/Common/GPU/D3D9/D3D9StateCache.h
index ae2dbd0ff4..1478442c0f 100644
--- a/Common/GPU/D3D9/D3D9StateCache.h
+++ b/Common/GPU/D3D9/D3D9StateCache.h
@@ -398,15 +398,3 @@ public:
 #undef STATE2
 
 extern DirectXState dxstate;
-
-struct GLExtensions {
-	bool OES_depth24;
-	bool OES_packed_depth_stencil;
-	bool OES_depth_texture;
-	bool EXT_discard_framebuffer;
-	bool FBO_ARB;
-};
-
-extern GLExtensions gl_extensions;
-
-void CheckGLExtensions();
diff --git a/Common/GPU/OpenGL/DataFormatGL.cpp b/Common/GPU/OpenGL/DataFormatGL.cpp
index 48e439a76d..1b2af548d8 100644
--- a/Common/GPU/OpenGL/DataFormatGL.cpp
+++ b/Common/GPU/OpenGL/DataFormatGL.cpp
@@ -1,4 +1,5 @@
 #include "Common/GPU/OpenGL/DataFormatGL.h"
+#include "Common/GPU/OpenGL/GLFeatures.h"
 #include "Common/Log.h"
 
 namespace Draw {
@@ -15,8 +16,16 @@ bool Thin3DFormatToGLFormatAndType(DataFormat fmt, GLuint &internalFormat, GLuin
 		break;
 
 	case DataFormat::R8_UNORM:
-		internalFormat = GL_RGBA;
-		format = GL_RED;
+		if (gl_extensions.IsGLES) {
+			internalFormat = GL_LUMINANCE;
+			format = GL_LUMINANCE;
+		} else if (gl_extensions.VersionGEThan(3, 0)) {
+			internalFormat = GL_RED;
+			format = GL_RED;
+		} else {
+			internalFormat = GL_RGBA;
+			format = GL_RED;
+		}
 		type = GL_UNSIGNED_BYTE;
 		alignment = 1;
 		break;