From bb6c8ef1c8aeb71ea3c02173d600ae6762520f4d Mon Sep 17 00:00:00 2001
From: Sungun Park <sungunpark@google.com>
Date: Tue, 12 Mar 2024 13:49:00 -0700
Subject: [PATCH] Add option FILAMENT_SAMPLES_STEREO_TYPE for samples/gltfio
 (#7658)

This option can be either "instanced" or "multiview", indicating what
stereoscopic rendering type shaders in samples/gltfio should be built
for.
---
 CMakeLists.txt                       | 10 ++++++++++
 libs/filamentapp/CMakeLists.txt      | 12 +++++++++++-
 libs/filamentapp/src/FilamentApp.cpp |  5 +++++
 libs/gltfio/CMakeLists.txt           |  9 ++++++++-
 samples/CMakeLists.txt               |  9 ++++++++-
 5 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 91ab2922d8..b18c4a5b4e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -531,6 +531,16 @@ else()
     option(FILAMENT_DISABLE_MATOPT "Disable material optimizations" ON)
 endif()
 
+# This only affects the prebuilt shader files in gltfio and samples, not filament library.
+# The value can be either "instanced" or "multiview".
+set(FILAMENT_SAMPLES_STEREO_TYPE "instanced" CACHE STRING
+    "Stereoscopic type that shader files in gltfio and samples are built for."
+)
+string(TOLOWER "${FILAMENT_SAMPLES_STEREO_TYPE}" FILAMENT_SAMPLES_STEREO_TYPE)
+if (NOT FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "instanced" AND NOT FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "multiview")
+    message(FATAL_ERROR "Invalid stereo type: \"${FILAMENT_SAMPLES_STEREO_TYPE}\" choose either \"instanced\" or \"multiview\" ")
+endif ()
+
 # ==================================================================================================
 # Material compilation flags
 # ==================================================================================================
diff --git a/libs/filamentapp/CMakeLists.txt b/libs/filamentapp/CMakeLists.txt
index a2c1d0dedb..2e0e95b7da 100644
--- a/libs/filamentapp/CMakeLists.txt
+++ b/libs/filamentapp/CMakeLists.txt
@@ -88,13 +88,23 @@ file(MAKE_DIRECTORY ${MATERIAL_DIR})
 file(MAKE_DIRECTORY ${RESOURCE_DIR})
 
 set(RESOURCE_BINS)
+
+set (MATC_FLAGS ${MATC_BASE_FLAGS})
+if (FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "instanced")
+    set (MATC_FLAGS ${MATC_FLAGS} -PstereoscopicType=instanced)
+    add_definitions(-DFILAMENT_SAMPLES_STEREO_TYPE_INSTANCED)
+elseif (FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "multiview")
+    set (MATC_FLAGS ${MATC_FLAGS} -PstereoscopicType=multiview)
+    add_definitions(-DFILAMENT_SAMPLES_STEREO_TYPE_MULTIVIEW)
+endif ()
+
 foreach (mat_src ${MATERIAL_SRCS})
     get_filename_component(localname "${mat_src}" NAME_WE)
     get_filename_component(fullname "${mat_src}" ABSOLUTE)
     set(output_path "${MATERIAL_DIR}/${localname}.filamat")
     add_custom_command(
             OUTPUT ${output_path}
-            COMMAND matc ${MATC_BASE_FLAGS} -o ${output_path} ${fullname}
+            COMMAND matc ${MATC_FLAGS} -o ${output_path} ${fullname}
             MAIN_DEPENDENCY ${mat_src}
             DEPENDS matc
             COMMENT "Compiling material ${mat_src} to ${output_path}"
diff --git a/libs/filamentapp/src/FilamentApp.cpp b/libs/filamentapp/src/FilamentApp.cpp
index 7e315b0da4..25f7126f83 100644
--- a/libs/filamentapp/src/FilamentApp.cpp
+++ b/libs/filamentapp/src/FilamentApp.cpp
@@ -605,6 +605,11 @@ FilamentApp::Window::Window(FilamentApp* filamentApp,
 
         Engine::Config engineConfig = {};
         engineConfig.stereoscopicEyeCount = config.stereoscopicEyeCount;
+#if defined(FILAMENT_SAMPLES_STEREO_TYPE_INSTANCED)
+        engineConfig.stereoscopicType = Engine::StereoscopicType::INSTANCED;
+#elif defined (FILAMENT_SAMPLES_STEREO_TYPE_MULTIVIEW)
+        engineConfig.stereoscopicType = Engine::StereoscopicType::MULTIVIEW;
+#endif
 
         if (backend == Engine::Backend::VULKAN) {
             #if defined(FILAMENT_DRIVER_SUPPORTS_VULKAN)
diff --git a/libs/gltfio/CMakeLists.txt b/libs/gltfio/CMakeLists.txt
index 3791525e29..2c1532cc16 100644
--- a/libs/gltfio/CMakeLists.txt
+++ b/libs/gltfio/CMakeLists.txt
@@ -69,6 +69,13 @@ set(TRANSPARENCY default)
 
 set(UBERZ_OUTPUT_PATH "${RESOURCE_DIR}/default.uberz")
 
+set (MATC_FLAGS ${MATC_BASE_FLAGS})
+if (FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "instanced")
+    set (MATC_FLAGS ${MATC_FLAGS} -PstereoscopicType=instanced)
+elseif (FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "multiview")
+    set (MATC_FLAGS ${MATC_FLAGS} -PstereoscopicType=multiview)
+endif ()
+
 function(build_ubershader NAME SRC SHADINGMODEL BLENDING)
     set(DEST "${RESOURCE_DIR}/${NAME}")
     configure_file(materials/${SRC}.mat.in "${DEST}.mat" COPYONLY)
@@ -85,7 +92,7 @@ function(build_ubershader NAME SRC SHADINGMODEL BLENDING)
 
     add_custom_command(
         OUTPUT "${NAME}.filamat"
-        COMMAND matc ${MATC_BASE_FLAGS} ${TEMPLATE_ARGS} -o "${NAME}.filamat" "${NAME}.mat"
+        COMMAND matc ${MATC_FLAGS} ${TEMPLATE_ARGS} -o "${NAME}.filamat" "${NAME}.mat"
         DEPENDS matc "${DEST}.mat"
         WORKING_DIRECTORY ${RESOURCE_DIR}
         COMMENT "Compiling material ${NAME}")
diff --git a/samples/CMakeLists.txt b/samples/CMakeLists.txt
index 9b7804e94f..027f2f7d6b 100644
--- a/samples/CMakeLists.txt
+++ b/samples/CMakeLists.txt
@@ -47,13 +47,20 @@ endif()
 
 file(MAKE_DIRECTORY ${MATERIAL_DIR})
 
+set (MATC_FLAGS ${MATC_BASE_FLAGS})
+if (FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "instanced")
+    set (MATC_FLAGS ${MATC_FLAGS} -PstereoscopicType=instanced)
+elseif (FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "multiview")
+    set (MATC_FLAGS ${MATC_FLAGS} -PstereoscopicType=multiview)
+endif ()
+
 foreach (mat_src ${MATERIAL_SRCS})
     get_filename_component(localname "${mat_src}" NAME_WE)
     get_filename_component(fullname "${mat_src}" ABSOLUTE)
     set(output_path "${MATERIAL_DIR}/${localname}.filamat")
     add_custom_command(
             OUTPUT ${output_path}
-            COMMAND matc ${MATC_BASE_FLAGS} -o ${output_path} ${fullname}
+            COMMAND matc ${MATC_FLAGS} -o ${output_path} ${fullname}
             MAIN_DEPENDENCY ${mat_src}
             DEPENDS matc
             COMMENT "Compiling material ${mat_src} to ${output_path}"