From abb0cbc98ea4821396c442ea2c4e655f2d687785 Mon Sep 17 00:00:00 2001
From: Sungun Park <sungunpark@google.com>
Date: Mon, 25 Mar 2024 14:43:04 -0700
Subject: [PATCH] Add FILAMENT_ENABLE_MULTIVIEW option (#7707)

This allows the engine to include multiview shader code for default
materials.
---
 CMakeLists.txt                  | 7 +++++++
 filament/CMakeLists.txt         | 7 ++++++-
 filament/src/details/Engine.cpp | 4 ++++
 filament/src/details/Skybox.cpp | 4 ++++
 4 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index b18c4a5b4e..ed32949873 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -45,6 +45,8 @@ option(FILAMENT_ENABLE_TSAN "Enable Thread Sanitizer" OFF)
 
 option(FILAMENT_ENABLE_FEATURE_LEVEL_0 "Enable Feature Level 0" ON)
 
+option(FILAMENT_ENABLE_MULTIVIEW "Enable multiview for Filament" OFF)
+
 set(FILAMENT_NDK_VERSION "" CACHE STRING
     "Android NDK version or version prefix to be used when building for Android."
 )
@@ -541,6 +543,11 @@ if (NOT FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "instanced" AND NOT FILAMENT_SAMPL
     message(FATAL_ERROR "Invalid stereo type: \"${FILAMENT_SAMPLES_STEREO_TYPE}\" choose either \"instanced\" or \"multiview\" ")
 endif ()
 
+# Compiling samples for multiview implies enabling multiview feature as well.
+if (FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "multiview")
+    set(FILAMENT_ENABLE_MULTIVIEW ON)
+endif ()
+
 # ==================================================================================================
 # Material compilation flags
 # ==================================================================================================
diff --git a/filament/CMakeLists.txt b/filament/CMakeLists.txt
index 66b78307cc..b978d2da1b 100644
--- a/filament/CMakeLists.txt
+++ b/filament/CMakeLists.txt
@@ -290,6 +290,11 @@ if (FILAMENT_ENABLE_FEATURE_LEVEL_0)
     add_definitions(-DFILAMENT_ENABLE_FEATURE_LEVEL_0)
 endif()
 
+# Whether to include MULTIVIEW materials.
+if (FILAMENT_ENABLE_MULTIVIEW)
+    add_definitions(-DFILAMENT_ENABLE_MULTIVIEW)
+endif()
+
 # ==================================================================================================
 # Definitions
 # ==================================================================================================
@@ -343,7 +348,7 @@ foreach (mat_src ${MATERIAL_SRCS})
     endif ()
 
     list(FIND MATERIAL_MULTIVIEW_SRCS ${mat_src} index)
-    if (${index} GREATER -1)
+    if (${index} GREATER -1 AND FILAMENT_ENABLE_MULTIVIEW)
         string(REGEX REPLACE "[.]filamat$" "_multiview.filamat" output_path_multiview ${output_path})
         add_custom_command(
                 OUTPUT ${output_path_multiview}
diff --git a/filament/src/details/Engine.cpp b/filament/src/details/Engine.cpp
index dbd49a8b71..5f7396fb3d 100644
--- a/filament/src/details/Engine.cpp
+++ b/filament/src/details/Engine.cpp
@@ -356,8 +356,12 @@ void FEngine::init() {
                     MATERIALS_DEFAULTMATERIAL_DATA, MATERIALS_DEFAULTMATERIAL_SIZE);
                 break;
             case StereoscopicType::MULTIVIEW:
+#ifdef FILAMENT_ENABLE_MULTIVIEW
                 defaultMaterialBuilder.package(
                     MATERIALS_DEFAULTMATERIAL_MULTIVIEW_DATA, MATERIALS_DEFAULTMATERIAL_MULTIVIEW_SIZE);
+#else
+                assert_invariant(false);
+#endif
                 break;
         }
         mDefaultMaterial = downcast(defaultMaterialBuilder.build(*const_cast<FEngine*>(this)));
diff --git a/filament/src/details/Skybox.cpp b/filament/src/details/Skybox.cpp
index 7fe6291bc8..39aca8ef8c 100644
--- a/filament/src/details/Skybox.cpp
+++ b/filament/src/details/Skybox.cpp
@@ -129,7 +129,11 @@ FMaterial const* FSkybox::createMaterial(FEngine& engine) {
                 builder.package(MATERIALS_SKYBOX_DATA, MATERIALS_SKYBOX_SIZE);
                 break;
             case Engine::StereoscopicType::MULTIVIEW:
+#ifdef FILAMENT_ENABLE_MULTIVIEW
                 builder.package(MATERIALS_SKYBOX_MULTIVIEW_DATA, MATERIALS_SKYBOX_MULTIVIEW_SIZE);
+#else
+                assert_invariant(false);
+#endif
                 break;
         }
     }