From 6ae04ea04a36610b387d8d0abd60fd5ad6fcaa9a Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Thu, 30 Apr 2026 10:02:22 +0000
Subject: [PATCH] tests: cover Vulkan mesh shader opt-in

Co-authored-by: Tim Fox <timfox@outlook.com>
---
 CMakeLists.txt                                |  7 ++
 .../scripts/test_vulkan_mesh_shader_opt_in.sh | 99 +++++++++++++++++++
 2 files changed, 106 insertions(+)
 create mode 100755 tests/scripts/test_vulkan_mesh_shader_opt_in.sh

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9d093a0b8..984d95d38 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2421,6 +2421,13 @@ add_test(NAME test_compile_engine_lto
 set_tests_properties(test_compile_engine_lto PROPERTIES
 	LABELS "unit;scripts;validation")
 
+add_test(NAME test_vulkan_mesh_shader_opt_in
+	COMMAND ${CMAKE_SOURCE_DIR}/tests/scripts/test_vulkan_mesh_shader_opt_in.sh
+	WORKING_DIRECTORY ${CMAKE_SOURCE_DIR})
+set_tests_properties(test_vulkan_mesh_shader_opt_in PROPERTIES
+	LABELS "unit;scripts;validation;renderer"
+	REQUIRED_FILES "${CMAKE_SOURCE_DIR}/tests/scripts/test_vulkan_mesh_shader_opt_in.sh")
+
 # --- Unit tests ---
 option(BUILD_UNIT_TESTS "Build unit tests" ON)
 if(BUILD_UNIT_TESTS)
diff --git a/tests/scripts/test_vulkan_mesh_shader_opt_in.sh b/tests/scripts/test_vulkan_mesh_shader_opt_in.sh
new file mode 100755
index 000000000..3126c649a
--- /dev/null
+++ b/tests/scripts/test_vulkan_mesh_shader_opt_in.sh
@@ -0,0 +1,99 @@
+#!/usr/bin/env bash
+# Guard optional VK_NV_mesh_shader setup so it remains an explicit, safe opt-in.
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+python3 - "$PROJECT_ROOT" <<'PY'
+import re
+import sys
+from pathlib import Path
+
+root = Path(sys.argv[1])
+
+
+def fail(message: str) -> None:
+    print(f"FAIL: {message}", file=sys.stderr)
+    sys.exit(1)
+
+
+def read(relpath: str) -> str:
+    path = root / relpath
+    if not path.is_file():
+        fail(f"missing file: {relpath}")
+    return path.read_text(encoding="utf-8")
+
+
+def require(text: str, needle: str, context: str) -> None:
+    if needle not in text:
+        fail(f"{context}: missing {needle!r}")
+
+
+def require_regex(text: str, pattern: str, context: str) -> None:
+    if not re.search(pattern, text, re.S):
+        fail(f"{context}: pattern not found: {pattern}")
+
+
+vk_instance = read("src/renderers/vulkan/vk_instance.c")
+tr_init = read("src/renderers/vulkan/tr_init.c")
+tr_local = read("src/renderers/vulkan/tr_local.h")
+vk_h = read("src/renderers/vulkan/vk.h")
+
+# Public renderer configuration must stay explicit, restart-bound, and default-off.
+require(
+    tr_init,
+    'r_vk_meshShaderNV = ri.Cvar_Get( "r_vk_meshShaderNV", "0", CVAR_ARCHIVE_ND | CVAR_LATCH );',
+    "mesh shader cvar registration",
+)
+require(
+    tr_init,
+    'ri.Cvar_CheckRange( r_vk_meshShaderNV, "0", "1", CV_INTEGER );',
+    "mesh shader cvar range",
+)
+require(
+    tr_init,
+    "Default off: extension is enabled for future mesh pipelines only; no draw path uses mesh shaders yet. Requires vid_restart.",
+    "mesh shader cvar description",
+)
+require(tr_local, "extern cvar_t\t*r_vk_meshShaderNV;", "mesh shader cvar declaration")
+require(vk_h, "qboolean meshShaderNV;", "mesh shader device state")
+
+# The extension can be detected from the driver, but it must only be appended
+# when the driver supports it, the user opted in, and there is room in the list.
+require_regex(
+    vk_instance,
+    r'else if \( strcmp\( ext, VK_NV_MESH_SHADER_EXTENSION_NAME \) == 0 \) \{\s*nvMeshShader = qtrue;\s*\}',
+    "mesh shader extension detection",
+)
+require_regex(
+    vk_instance,
+    r'vk\.meshShaderNV = qfalse;.*?if \( nvMeshShader && r_vk_meshShaderNV && r_vk_meshShaderNV->integer &&\s*'
+    r'device_extension_count < ARRAY_LEN\( device_extension_list \) \) \{\s*'
+    r'device_extension_list\[ device_extension_count\+\+ \] = VK_NV_MESH_SHADER_EXTENSION_NAME;\s*'
+    r'vk\.meshShaderNV = qtrue;\s*'
+    r'ri\.Printf\( PRINT_ALL, "\[VK\] VK_NV_mesh_shader enabled \(experimental; no mesh draw path yet\)\\n" \);\s*'
+    r'\}',
+    "mesh shader extension opt-in gate",
+)
+
+# Device features must be chained only when the extension was actually enabled.
+# Keep task shaders off until a draw path exists; enable only meshShader.
+require_regex(
+    vk_instance,
+    r'if \( vk\.meshShaderNV \) \{\s*'
+    r'Com_Memset\( &mesh_shader_features_nv, 0, sizeof\( mesh_shader_features_nv \) \);\s*'
+    r'mesh_shader_features_nv\.sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_MESH_SHADER_FEATURES_NV;\s*'
+    r'mesh_shader_features_nv\.pNext = \(void \*\)\(uintptr_t\)device_desc\.pNext;\s*'
+    r'mesh_shader_features_nv\.taskShader = VK_FALSE;\s*'
+    r'mesh_shader_features_nv\.meshShader = VK_TRUE;\s*'
+    r'device_desc\.pNext = &mesh_shader_features_nv;\s*'
+    r'\}',
+    "mesh shader feature pNext chain",
+)
+
+if vk_instance.count("VK_NV_MESH_SHADER_EXTENSION_NAME") < 2:
+    fail("mesh shader extension should be both detected and conditionally enabled")
+
+print("PASS: test_vulkan_mesh_shader_opt_in")
+PY