Add FILAMENT_ENABLE_MULTIVIEW option (#7707)

This allows the engine to include multiview shader code for default
materials.

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
 # ==================================================================================================

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}

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)));

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;
         }
     }