From c7ff1e726c6243e495608d433c5ab9b31df3aee4 Mon Sep 17 00:00:00 2001
From: kd-11 <karokidii@gmail.com>
Date: Sun, 10 May 2026 20:17:21 +0300
Subject: [PATCH] gl: Implement emulated Z comparison support

---
 rpcs3/Emu/RSX/GL/GLDraw.cpp            |  9 +++++++++
 rpcs3/Emu/RSX/GL/GLFragmentProgram.cpp |  6 ++++++
 rpcs3/Emu/RSX/GL/GLProgramBuffer.h     |  7 +++++++
 rpcs3/Emu/RSX/GL/GLTextureCache.h      |  8 ++------
 rpcs3/Emu/RSX/GL/glutils/barriers.h    | 16 ++++++++++++++++
 rpcs3/GLGSRender.vcxproj               |  1 +
 rpcs3/GLGSRender.vcxproj.filters       |  3 +++
 7 files changed, 44 insertions(+), 6 deletions(-)
 create mode 100644 rpcs3/Emu/RSX/GL/glutils/barriers.h

diff --git a/rpcs3/Emu/RSX/GL/GLDraw.cpp b/rpcs3/Emu/RSX/GL/GLDraw.cpp
index c57eba811e..57a9b08a17 100644
--- a/rpcs3/Emu/RSX/GL/GLDraw.cpp
+++ b/rpcs3/Emu/RSX/GL/GLDraw.cpp
@@ -543,6 +543,15 @@ void GLGSRender::bind_texture_env()
 			cmd->bind_texture(GL_VERTEX_TEXTURES_START + i, GL_TEXTURE_2D, GL_NONE);
 		}
 	}
+
+	if (current_fragment_program.ctrl & RSX_SHADER_CONTROL_EMULATE_DEPTH_COMPARE)
+	{
+		ensure(m_rtts.m_bound_depth_stencil.first, "Invalid FBO setup");
+		gl::insert_texture_barrier();
+
+		auto view = m_rtts.m_bound_depth_stencil.second->get_view(rsx::default_remap_vector, gl::image_aspect::depth);
+		view->bind(cmd, GL_TEMP_IMAGE_SLOT(0));
+	}
 }
 
 void GLGSRender::bind_interpreter_texture_env()
diff --git a/rpcs3/Emu/RSX/GL/GLFragmentProgram.cpp b/rpcs3/Emu/RSX/GL/GLFragmentProgram.cpp
index 5271390af9..efac22b3ed 100644
--- a/rpcs3/Emu/RSX/GL/GLFragmentProgram.cpp
+++ b/rpcs3/Emu/RSX/GL/GLFragmentProgram.cpp
@@ -167,6 +167,11 @@ void GLFragmentDecompilerThread::insertConstants(std::stringstream & OS)
 		}
 	}
 
+	if (m_prog.ctrl & RSX_SHADER_CONTROL_EMULATE_DEPTH_COMPARE)
+	{
+		OS << "uniform sampler2D frag_depth;\n";
+	}
+
 	OS << "\n";
 
 	if (!properties.constant_offsets.empty())
@@ -238,6 +243,7 @@ void GLFragmentDecompilerThread::insertGlobalFunctions(std::stringstream &OS)
 	m_shader_props.require_shadowProj_ops = properties.shadow_sampler_mask != 0 && properties.has_texShadowProj;
 	m_shader_props.require_alpha_kill = !!(m_prog.ctrl & RSX_SHADER_CONTROL_TEXTURE_ALPHA_KILL);
 	m_shader_props.require_color_format_convert = !!(m_prog.ctrl & RSX_SHADER_CONTROL_TEXTURE_FORMAT_CONVERT);
+	m_shader_props.emulate_depth_compare = !!(m_prog.ctrl & RSX_SHADER_CONTROL_EMULATE_DEPTH_COMPARE);
 
 	glsl::insert_glsl_legacy_function(OS, m_shader_props);
 }
diff --git a/rpcs3/Emu/RSX/GL/GLProgramBuffer.h b/rpcs3/Emu/RSX/GL/GLProgramBuffer.h
index 8dd34caacd..615e2e4b6d 100644
--- a/rpcs3/Emu/RSX/GL/GLProgramBuffer.h
+++ b/rpcs3/Emu/RSX/GL/GLProgramBuffer.h
@@ -101,6 +101,13 @@ struct GLTraits
 			// Bind locations 0 and 1 to the stream buffers
 			program->uniforms[0] = GL_STREAM_BUFFER_START + 0;
 			program->uniforms[1] = GL_STREAM_BUFFER_START + 1;
+
+			// Optional inputs
+			int location = 0;
+			if (program->uniforms.has_location("frag_depth", &location))
+			{
+				program->uniforms[location] = GL_TEMP_IMAGE_SLOT(0);
+			}
 		};
 
 		auto pipeline = compiler->compile(flags, post_create_func, post_link_func, callback);
diff --git a/rpcs3/Emu/RSX/GL/GLTextureCache.h b/rpcs3/Emu/RSX/GL/GLTextureCache.h
index 93c0ba2f5c..48a4ba98a0 100644
--- a/rpcs3/Emu/RSX/GL/GLTextureCache.h
+++ b/rpcs3/Emu/RSX/GL/GLTextureCache.h
@@ -2,6 +2,7 @@
 
 #include "Emu/RSX/GL/GLTexture.h"
 #include "GLRenderTargets.h"
+#include "glutils/barriers.h"
 #include "glutils/blitter.h"
 #include "glutils/sync.hpp"
 
@@ -804,12 +805,7 @@ namespace gl
 
 		void insert_texture_barrier(gl::command_context&, gl::texture*, bool) override
 		{
-			auto &caps = gl::get_driver_caps();
-
-			if (caps.ARB_texture_barrier_supported)
-				glTextureBarrier();
-			else if (caps.NV_texture_barrier_supported)
-				glTextureBarrierNV();
+			gl::insert_texture_barrier();
 		}
 
 		bool render_target_format_is_compatible(gl::texture* tex, u32 gcm_format) override
diff --git a/rpcs3/Emu/RSX/GL/glutils/barriers.h b/rpcs3/Emu/RSX/GL/glutils/barriers.h
new file mode 100644
index 0000000000..920e4c7088
--- /dev/null
+++ b/rpcs3/Emu/RSX/GL/glutils/barriers.h
@@ -0,0 +1,16 @@
+#pragma once
+
+#include "common.h"
+
+namespace gl
+{
+	static inline void insert_texture_barrier()
+	{
+		auto& caps = gl::get_driver_caps();
+
+		if (caps.ARB_texture_barrier_supported)
+			glTextureBarrier();
+		else if (caps.NV_texture_barrier_supported)
+			glTextureBarrierNV();
+	}
+}
diff --git a/rpcs3/GLGSRender.vcxproj b/rpcs3/GLGSRender.vcxproj
index dbaffc5d00..8d6ba02dd9 100644
--- a/rpcs3/GLGSRender.vcxproj
+++ b/rpcs3/GLGSRender.vcxproj
@@ -61,6 +61,7 @@
     <ClInclude Include="Emu\RSX\GL\GLProcTable.h" />
     <ClInclude Include="Emu\RSX\GL\GLProgramBuffer.h" />
     <ClInclude Include="Emu\RSX\GL\GLResolveHelper.h" />
+    <ClInclude Include="Emu\RSX\GL\glutils\barriers.h" />
     <ClInclude Include="Emu\RSX\GL\glutils\blitter.h" />
     <ClInclude Include="Emu\RSX\GL\glutils\buffer_object.h" />
     <ClInclude Include="Emu\RSX\GL\glutils\capabilities.h" />
diff --git a/rpcs3/GLGSRender.vcxproj.filters b/rpcs3/GLGSRender.vcxproj.filters
index 4866b14643..c4fe752d10 100644
--- a/rpcs3/GLGSRender.vcxproj.filters
+++ b/rpcs3/GLGSRender.vcxproj.filters
@@ -122,6 +122,9 @@
     </ClInclude>
     <ClInclude Include="Emu\RSX\GL\GLDMA.h" />
     <ClInclude Include="Emu\RSX\GL\GLResolveHelper.h" />
+    <ClInclude Include="Emu\RSX\GL\glutils\barriers.h">
+      <Filter>glutils</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <Filter Include="glutils">