From 2460050e8dd6975d992e51c2c49200ed35583365 Mon Sep 17 00:00:00 2001
From: wheremyfoodat <44909372+wheremyfoodat@users.noreply.github.com>
Date: Sun, 13 Oct 2024 23:47:27 +0300
Subject: [PATCH] GLES: Add support for GL_ARM_shader_framebuffer_fetch

---
 include/renderer_gl/gl_driver.hpp    |  5 ++++-
 src/core/PICA/shader_gen_glsl.cpp    | 19 ++++++++++++++++---
 src/core/renderer_gl/renderer_gl.cpp |  3 ++-
 3 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/include/renderer_gl/gl_driver.hpp b/include/renderer_gl/gl_driver.hpp
index c8a1bf85..a15c061f 100644
--- a/include/renderer_gl/gl_driver.hpp
+++ b/include/renderer_gl/gl_driver.hpp
@@ -4,6 +4,9 @@
 // Stuff like whether specific extensions are supported, and potentially things like OpenGL context information
 namespace OpenGL {
 	struct Driver {
-		bool supportsFbFetch = false;
+		bool supportsExtFbFetch = false;
+		bool supportsArmFbFetch = false;
+
+		bool supportFbFetch() const { return supportsExtFbFetch || supportsArmFbFetch; }
 	};
 }  // namespace OpenGL
\ No newline at end of file
diff --git a/src/core/PICA/shader_gen_glsl.cpp b/src/core/PICA/shader_gen_glsl.cpp
index b77f03dc..de406f53 100644
--- a/src/core/PICA/shader_gen_glsl.cpp
+++ b/src/core/PICA/shader_gen_glsl.cpp
@@ -108,11 +108,24 @@ std::string FragmentGenerator::generate(const FragmentConfig& config, void* driv
 	}
 
 	// For GLES we need to enable & use the framebuffer fetch extension in order to emulate logic ops
-	const bool emitLogicOps = api == API::GLES && config.outConfig.logicOpMode != PICA::LogicOpMode::Copy && driverInfo != nullptr &&
-							  static_cast<OpenGL::Driver*>(driverInfo)->supportsFbFetch;
+	bool emitLogicOps = api == API::GLES && config.outConfig.logicOpMode != PICA::LogicOpMode::Copy && driverInfo != nullptr;
 
 	if (emitLogicOps) {
-		ret += "\n#extension GL_EXT_shader_framebuffer_fetch : enable\n";
+		auto driver = static_cast<OpenGL::Driver*>(driverInfo);
+
+		// If the driver does not support framebuffer fetch at all, don't emit logic op code
+		if (!driver->supportFbFetch()) {
+			emitLogicOps = false;
+		}
+		
+		// Figure out which fb fetch extension we have and enable it
+		else {
+			if (driver->supportsExtFbFetch) {
+				ret += "\n#extension GL_EXT_shader_framebuffer_fetch : enable\n";
+			} else if (driver->supportsArmFbFetch) {
+				ret += "\n#extension GL_ARM_shader_framebuffer_fetch : enable\n#define gl_LastFragData gl_LastFragColorARM\n";
+			}
+		}
 	}
 
 	bool unimplementedFlag = false;
diff --git a/src/core/renderer_gl/renderer_gl.cpp b/src/core/renderer_gl/renderer_gl.cpp
index 7c916122..ecbee3a2 100644
--- a/src/core/renderer_gl/renderer_gl.cpp
+++ b/src/core/renderer_gl/renderer_gl.cpp
@@ -168,7 +168,8 @@ void RendererGL::initGraphicsContextInternal() {
 	reset();
 
 	// Populate our driver info structure
-	driverInfo.supportsFbFetch = GLAD_GL_EXT_shader_framebuffer_fetch != 0;
+	driverInfo.supportsExtFbFetch = GLAD_GL_EXT_shader_framebuffer_fetch != 0;
+	driverInfo.supportsArmFbFetch = GLAD_GL_ARM_shader_framebuffer_fetch != 0;
 
 	// Initialize the default vertex shader used with shadergen
 	std::string defaultShadergenVSSource = fragShaderGen.getDefaultVertexShader();