From 1b38cda0d51f0648e6e488b196851b48ca56d824 Mon Sep 17 00:00:00 2001
From: Ben Doherty <bendoherty@google.com>
Date: Wed, 8 May 2024 14:42:40 -0700
Subject: [PATCH] Add preferredShaderLanguage Java bindings (#7835)

---
 .../filament-android/src/main/cpp/Engine.cpp  |  4 +++-
 .../com/google/android/filament/Engine.java   | 24 +++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/android/filament-android/src/main/cpp/Engine.cpp b/android/filament-android/src/main/cpp/Engine.cpp
index 482d54834b..a4ace37853 100644
--- a/android/filament-android/src/main/cpp/Engine.cpp
+++ b/android/filament-android/src/main/cpp/Engine.cpp
@@ -518,6 +518,7 @@ extern "C" JNIEXPORT void JNICALL Java_com_google_android_filament_Engine_nSetBu
         jint stereoscopicType, jlong stereoscopicEyeCount,
         jlong resourceAllocatorCacheSizeMB, jlong resourceAllocatorCacheMaxAge,
         jboolean disableHandleUseAfterFreeCheck,
+        jint preferredShaderLanguage,
         jboolean forceGLES2Context) {
     Engine::Builder* builder = (Engine::Builder*) nativeBuilder;
     Engine::Config config = {
@@ -534,7 +535,8 @@ extern "C" JNIEXPORT void JNICALL Java_com_google_android_filament_Engine_nSetBu
             .resourceAllocatorCacheSizeMB = (uint32_t) resourceAllocatorCacheSizeMB,
             .resourceAllocatorCacheMaxAge = (uint8_t) resourceAllocatorCacheMaxAge,
             .disableHandleUseAfterFreeCheck = (bool) disableHandleUseAfterFreeCheck,
-            .forceGLES2Context = (bool) forceGLES2Context
+            .preferredShaderLanguage = (Engine::Config::ShaderLanguage) preferredShaderLanguage,
+            .forceGLES2Context = (bool) forceGLES2Context,
     };
     builder->config(&config);
 }
diff --git a/android/filament-android/src/main/java/com/google/android/filament/Engine.java b/android/filament-android/src/main/java/com/google/android/filament/Engine.java
index bfb17aa5ae..8d53c412b4 100644
--- a/android/filament-android/src/main/java/com/google/android/filament/Engine.java
+++ b/android/filament-android/src/main/java/com/google/android/filament/Engine.java
@@ -226,6 +226,7 @@ public class Engine {
                     config.stereoscopicType.ordinal(), config.stereoscopicEyeCount,
                     config.resourceAllocatorCacheSizeMB, config.resourceAllocatorCacheMaxAge,
                     config.disableHandleUseAfterFreeCheck,
+                    config.preferredShaderLanguage.ordinal(),
                     config.forceGLES2Context);
             return this;
         }
@@ -430,6 +431,28 @@ public class Engine {
          */
         public boolean disableHandleUseAfterFreeCheck = false;
 
+        /*
+         * Sets a preferred shader language for Filament to use.
+         *
+         * The Metal backend supports two shader languages: MSL (Metal Shading Language) and
+         * METAL_LIBRARY (precompiled .metallib). This option controls which shader language is
+         * used when materials contain both.
+         *
+         * By default, when preferredShaderLanguage is unset, Filament will prefer METAL_LIBRARY
+         * shaders if present within a material, falling back to MSL. Setting
+         * preferredShaderLanguage to ShaderLanguage::MSL will instead instruct Filament to check
+         * for the presence of MSL in a material first, falling back to METAL_LIBRARY if MSL is not
+         * present.
+         *
+         * When using a non-Metal backend, setting this has no effect.
+         */
+        public enum ShaderLanguage {
+            DEFAULT,
+            MSL,
+            METAL_LIBRARY,
+        };
+        public ShaderLanguage preferredShaderLanguage = ShaderLanguage.DEFAULT;
+
         /*
          * When the OpenGL ES backend is used, setting this value to true will force a GLES2.0
          * context if supported by the Platform, or if not, will have the backend pretend
@@ -1362,6 +1385,7 @@ public class Engine {
             int stereoscopicType, long stereoscopicEyeCount,
             long resourceAllocatorCacheSizeMB, long resourceAllocatorCacheMaxAge,
             boolean disableHandleUseAfterFreeCheck,
+            int preferredShaderLanguage,
             boolean forceGLES2Context);
     private static native void nSetBuilderFeatureLevel(long nativeBuilder, int ordinal);
     private static native void nSetBuilderSharedContext(long nativeBuilder, long sharedContext);