From b0bd6470f3bc1f1145078152707490280538dbca Mon Sep 17 00:00:00 2001
From: nmzik <Nmzik@mail.ru>
Date: Sun, 16 Aug 2026 16:54:27 +0200
Subject: [PATCH] graphics: accept AGC vertex-buffer-only shaders

---
 src/graphics/shader/shader.cpp               |  2 +-
 src/graphics/shader/shaderVertexMetadata.cpp | 17 +++++++++------
 tests/ShaderVertexMetadataTests.cpp          | 22 ++++++++++++++++++++
 3 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/src/graphics/shader/shader.cpp b/src/graphics/shader/shader.cpp
index 6643341a4..52cbe4a4e 100644
--- a/src/graphics/shader/shader.cpp
+++ b/src/graphics/shader/shader.cpp
@@ -811,7 +811,7 @@ static bool ShaderGetStaticInputInfoVS(const HW::VertexShaderInfo& regs,
 		return false;
 	}
 
-	if (metadata.vertex_buffer_reg >= 0) {
+	if (metadata.vertex_attrib_reg >= 0) {
 		info.fetch_external   = false;
 		info.fetch_embedded   = true;
 		info.fetch_attrib_reg = metadata.vertex_attrib_reg;
diff --git a/src/graphics/shader/shaderVertexMetadata.cpp b/src/graphics/shader/shaderVertexMetadata.cpp
index e5acd56a4..2b81a1c11 100644
--- a/src/graphics/shader/shaderVertexMetadata.cpp
+++ b/src/graphics/shader/shaderVertexMetadata.cpp
@@ -56,16 +56,21 @@ bool ShaderReadVertexMetadata(const ShaderMappedData& data, uint32_t max_user_sg
 		}
 	}
 
-	const bool embedded = next.vertex_buffer_reg >= 0 || next.vertex_attrib_reg >= 0;
-	if (!embedded) {
+	if (next.vertex_attrib_reg >= 0 && next.vertex_buffer_reg < 0) {
+		return Fail(error, "vertex attribute table requires a vertex buffer table");
+	}
+	if (next.vertex_buffer_reg < 0) {
 		metadata = next;
 		return true;
 	}
-	if (next.vertex_buffer_reg < 0 || next.vertex_attrib_reg < 0) {
-		return Fail(error, "vertex buffer and attribute tables must be supplied together");
+	if (static_cast<uint32_t>(next.vertex_buffer_reg) + 1u >= max_user_sgprs) {
+		return Fail(error, "vertex table pointer exceeds the user-SGPR domain");
 	}
-	if (static_cast<uint32_t>(next.vertex_buffer_reg) + 1u >= max_user_sgprs ||
-	    static_cast<uint32_t>(next.vertex_attrib_reg) + 1u >= max_user_sgprs) {
+	if (next.vertex_attrib_reg < 0) {
+		metadata = next;
+		return true;
+	}
+	if (static_cast<uint32_t>(next.vertex_attrib_reg) + 1u >= max_user_sgprs) {
 		return Fail(error, "vertex table pointer exceeds the user-SGPR domain");
 	}
 	if (data.num_input_semantics == 0 ||
diff --git a/tests/ShaderVertexMetadataTests.cpp b/tests/ShaderVertexMetadataTests.cpp
index abf016c9f..7d1078743 100644
--- a/tests/ShaderVertexMetadataTests.cpp
+++ b/tests/ShaderVertexMetadataTests.cpp
@@ -57,6 +57,22 @@ void TestValidAndInvalidMetadata() {
 	          output.input_semantics_count == 1,
 	      "valid AGC vertex metadata was decoded incorrectly");
 
+	Fixture buffer_only;
+	buffer_only.offsets[static_cast<size_t>(AgcDirectResourceType::PtrVertexAttribDescTable)] =
+	    AGC_ILLEGAL_DIRECT_OFFSET;
+	buffer_only.mapped.input_semantics     = nullptr;
+	buffer_only.mapped.num_input_semantics = 0;
+	Check(ShaderReadVertexMetadata(buffer_only.mapped, 64, output, &error),
+	      "vertex-buffer-only AGC metadata was rejected");
+	Check(output.vertex_buffer_reg == 2 && output.vertex_attrib_reg == -1 &&
+	          output.input_semantics_count == 0,
+	      "vertex-buffer-only AGC metadata was decoded incorrectly");
+
+	Fixture attrib_only;
+	attrib_only.offsets[static_cast<size_t>(AgcDirectResourceType::PtrVertexBufferTable)] =
+	    AGC_ILLEGAL_DIRECT_OFFSET;
+	CheckRejected(attrib_only.mapped, "vertex-attribute-only AGC metadata was accepted");
+
 	auto missing_header      = fixture.mapped;
 	missing_header.user_data = nullptr;
 	CheckRejected(missing_header, "missing AGC user-data header was accepted");
@@ -79,6 +95,12 @@ void TestValidAndInvalidMetadata() {
 	    63;
 	CheckRejected(excessive_register.mapped, "out-of-domain vertex table SGPR was accepted");
 
+	Fixture excessive_attrib_register;
+	excessive_attrib_register
+	    .offsets[static_cast<size_t>(AgcDirectResourceType::PtrVertexAttribDescTable)] = 63;
+	CheckRejected(excessive_attrib_register.mapped,
+	              "out-of-domain vertex attribute table SGPR was accepted");
+
 	Fixture missing_semantics;
 	missing_semantics.mapped.input_semantics = nullptr;
 	CheckRejected(missing_semantics.mapped, "missing vertex semantic array was accepted");