From 552ada02d7086dac422e437e03a3d761c05317c8 Mon Sep 17 00:00:00 2001
From: Stephen Saunders <srsaunders@rogers.com>
Date: Sun, 30 Jan 2022 12:39:09 -0500
Subject: [PATCH] macOS Vulkan: Check and disable MoltenVK's use of Metal
 argument buffers for shader allocation scalability

(cherry picked from commit 939ab3b6396bd7196ce7f0c16cf59c83ebdc6a4e)
---
 neo/cmake-xcode-vulkan-debug.sh          |  7 ++++---
 neo/renderer/Vulkan/RenderBackend_VK.cpp | 21 +++++++++++++++------
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/neo/cmake-xcode-vulkan-debug.sh b/neo/cmake-xcode-vulkan-debug.sh
index 31464dcc..3d8a1e3d 100755
--- a/neo/cmake-xcode-vulkan-debug.sh
+++ b/neo/cmake-xcode-vulkan-debug.sh
@@ -4,6 +4,7 @@ mkdir xcode-vulkan-debug
 cd xcode-vulkan-debug
 # note 1: remove or set -DCMAKE_SUPPRESS_REGENERATION=OFF to reenable ZERO_CHECK target which checks for CMakeLists.txt changes and re-runs CMake before builds
 #         however, if ZERO_CHECK is reenabled **must** add VULKAN_SDK location to Xcode Custom Paths (under Prefs/Locations) otherwise build failures may occur
-# note 2: env variable MVK_CONFIG_FULL_IMAGE_VIEW_SWIZZLE=1 enables imageViewFormatSwizzle which may be required on older macOS versions or hardware (see vulkaninfo)
-# note 3: env variable VK_LAYER_MESSAGE_ID_FILTER=0xb408bc0b suppresses validation layer error messages caused by exceeding maxSamplerAllocationCount limit
-cmake -G Xcode -DCMAKE_BUILD_TYPE=Debug -DSDL2=ON -DUSE_VULKAN=ON -DSPIRV_SHADERC=OFF -DCMAKE_XCODE_GENERATE_SCHEME=ON -DCMAKE_XCODE_SCHEME_ENVIRONMENT="MVK_CONFIG_FULL_IMAGE_VIEW_SWIZZLE=1;VK_LAYER_MESSAGE_ID_FILTER=0xb408bc0b" -DCMAKE_SUPPRESS_REGENERATION=ON -DOPENAL_LIBRARY=/usr/local/opt/openal-soft/lib/libopenal.dylib -DOPENAL_INCLUDE_DIR=/usr/local/opt/openal-soft/include ../neo -Wno-dev
+# note 2: env variable MVK_CONFIG_FULL_IMAGE_VIEW_SWIZZLE=1 enables MoltenVK's image view swizzle which may be required on older macOS versions or hardware (see vulkaninfo)
+# note 3: env variable MVK_CONFIG_USE_METAL_ARGUMENT_BUFFERS=0 disables MoltenVK's use of Metal argument buffers, which then removes the limit on sampler allocation
+# note 4: env variable VK_LAYER_MESSAGE_ID_FILTER=0xb408bc0b suppresses validation layer error messages caused by exceeding the maxSamplerAllocationCount limit
+cmake -G Xcode -DCMAKE_BUILD_TYPE=Debug -DSDL2=ON -DUSE_VULKAN=ON -DSPIRV_SHADERC=OFF -DCMAKE_XCODE_GENERATE_SCHEME=ON -DCMAKE_XCODE_SCHEME_ENVIRONMENT="MVK_CONFIG_FULL_IMAGE_VIEW_SWIZZLE=1;MVK_CONFIG_USE_METAL_ARGUMENT_BUFFERS=0;VK_LAYER_MESSAGE_ID_FILTER=0xb408bc0b" -DCMAKE_SUPPRESS_REGENERATION=ON -DOPENAL_LIBRARY=/usr/local/opt/openal-soft/lib/libopenal.dylib -DOPENAL_INCLUDE_DIR=/usr/local/opt/openal-soft/include ../neo -Wno-dev
diff --git a/neo/renderer/Vulkan/RenderBackend_VK.cpp b/neo/renderer/Vulkan/RenderBackend_VK.cpp
index c0f901d4..b4943741 100644
--- a/neo/renderer/Vulkan/RenderBackend_VK.cpp
+++ b/neo/renderer/Vulkan/RenderBackend_VK.cpp
@@ -815,17 +815,26 @@ static void CreateLogicalDeviceAndQueues()
 
 	vkGetPhysicalDeviceFeatures2( vkcontext.physicalDevice, &deviceFeatures2 );
 #if defined(USE_MoltenVK)
-    // SRS - Check if we have native image swizzling, and if not, enable MoltenVK's emulation
+    MVKConfiguration    pConfig;
+    size_t              pConfigSize = sizeof( pConfig );
+
+    ID_VK_CHECK( vkGetMoltenVKConfigurationMVK( vkcontext.instance, &pConfig, &pConfigSize ) );
+    
+    // SRS - If we don't have native image view swizzle, enable MoltenVK's image view swizzle feature
     if( portabilityFeatures.imageViewFormatSwizzle == VK_FALSE )
     {
-        MVKConfiguration    pConfig;
-        size_t              pConfigSize = sizeof( pConfig );
-
-        idLib::Printf( "Enabling MoltenVK fullImageViewSwizzle...\n" );
-        ID_VK_CHECK( vkGetMoltenVKConfigurationMVK( vkcontext.instance, &pConfig, &pConfigSize ) );
+        idLib::Printf( "Enabling MoltenVK's image view swizzle...\n" );
         pConfig.fullImageViewSwizzle = VK_TRUE;
         ID_VK_CHECK( vkSetMoltenVKConfigurationMVK( vkcontext.instance, &pConfig, &pConfigSize ) );
     }
+
+    // SRS - If MoltenVK's Metal argument buffer feature is on, disable it for sampler scalability
+    if( pConfig.useMetalArgumentBuffers == VK_TRUE )
+    {
+        idLib::Printf( "Disabling MoltenVK's Metal argument buffers...\n" );
+        pConfig.useMetalArgumentBuffers = VK_FALSE;
+        ID_VK_CHECK( vkSetMoltenVKConfigurationMVK( vkcontext.instance, &pConfig, &pConfigSize ) );
+    }
 #endif
 #else
 	VkPhysicalDeviceFeatures deviceFeatures = {};