fetchDependencies - external/github.com/KhronosGroup/MoltenVK - Git at Google

 #!/bin/bash
 #
 # Copyright (c) 2016-2022 The Brenwill Workshop Ltd.
 #
 # fetchDependencies - Retrieves the correct versions of all dependencies
 #
 # macOS usage: ./fetchDependencies [--macos] [--ios] [--iossim] [--tvos] [--tvossim] [--all] [--none]
 #                                  [-v] [--debug] [--build-spirv-tools]
 #                                  [--v-headers-root path] [--spirv-cross-root path] [--glslang-root path]
 #
 #      --macos
 #              Build the external libraries for the macOS platform.
 #
 #      --ios
 #              Build the external libraries for the iOS platform.
 #
 #      --iossim
 #              Build the external libraries for the iOS Simulator platform.
 #
 #      --maccat
 #              Build the external libraries for the Mac Catalyst platform.
 #
 #      --tvos
 #              Build the external libraries for the tvOS platform.
 #
 #      --tvossim
 #              Build the external libraries for the tvOS Simulator platform.
 #
 #      --all
 #              Equivalent to specifying [--macos --ios --iossim --maccat --tvos --tvossim].
 #              Results in one XCFramework for each external library, each containing
 #              binaries for all supported platforms.
 #
 #      --none
 #              Don't build the external libraries for any platform (this is the default).
 #
 #      Multiple platform options may be specified. At least one platform option must be specified.
 #
 #      --asan
 #              Build the external libraries against Address Sanitizer, which may be useful when debugging
 #              and tracing calls into those libraries.
 #
 #      --tsan
 #              Build the external libraries against Thread Sanitizer, which may be useful when debugging
 #              and tracing calls into those libraries.
 #
 #      --ubsan
 #              Build the external libraries against Undefined Behavior Sanitizer, which may be useful when debugging
 #              and tracing calls into those libraries.
 #
 #      --debug
 #              Build the external libraries in Debug mode, which may be useful when debugging
 #              and tracing calls into those libraries.
 #
 #      --parallel-build
 #              Build the external libraries in parallel using background processes.
 #
 #      --no-parallel-build
 #              Build the external libraries serially instead of in parallel. This is the default.
 #
 #      --glslang-root path
 #              "path" specifies a directory path to a KhronosGroup/glslang repository.
 #              This repository does need to be built and the build directory must be in the
 #              specified directory. It should be built the same way this script builds it.
 #
 #      --build-spirv-tools
 #              Build the full spirv-tools distribution. Normally this is not needed, because
 #              MoltenVK includes a template of pre-generated SPIRV-Tools header files, which
 #              is all that is needed. Avoiding the spirv-tools build saves significant time
 #              during the running of this script, and is necessary during CI because Travis CI
 #              cannot support the required use of Python3 by the spirv-tools build. This flag
 #              is used by the packagePregenSpirvToolsHeaders script which regenerates the
 #              spirv-tools header files and repackages the Templates/spirv-tools/build.zip
 #              file when the spirv-tools library version is upgraded.
 #
 #      --spirv-cross-root path
 #              "path" specifies a directory path to a KhronosGroup/SPIRV-Cross repository.
 #              This repository does not have to be built.
 #
 #      -v      verbose output
 #
 #      --v-headers-root path
 #              "path" specifies a directory path to a KhronosGroup/Vulkan-Headers repository.
 #              This repository does not have to be built.
 #

 set -e

 # ----------------- Functions -------------------

 BLD_NONE=""
 BLD_IOS=""
 BLD_IOS_SIM=""
 BLD_MAC_CAT=""
 BLD_TVOS=""
 BLD_TVOS_SIM=""
 BLD_MACOS=""
 BLD_SPECIFIED=""
 XC_CONFIG="Release"
 XC_BUILD_VERBOSITY="-quiet"
 XC_USE_BCKGND=""
 XC_USE_ASAN="NO"
 XC_USE_TSAN="NO"
 XC_USE_UBSAN="NO"
 V_HEADERS_ROOT=""
 SPIRV_CROSS_ROOT=""
 GLSLANG_ROOT=""
 BLD_SPV_TLS=""

 while (( "$#" )); do
   case "$1" in
        --ios)
          BLD_IOS="Y"
          shift 1
          ;;
        --iossim)
          BLD_IOS_SIM="Y"
          shift 1
          ;;
        --maccat)
          BLD_MAC_CAT="Y"
          shift 1
          ;;
        --tvos)
          BLD_TVOS="Y"
          shift 1
          ;;
        --tvossim)
          BLD_TVOS_SIM="Y"
          shift 1
          ;;
        --macos)
          BLD_MACOS="Y"
          shift 1
          ;;
        --all)
          BLD_IOS="Y"
          BLD_IOS_SIM="Y"
          BLD_MAC_CAT="Y"
          BLD_TVOS="Y"
          BLD_TVOS_SIM="Y"
          BLD_MACOS="Y"
          shift 1
          ;;
        --none)
          BLD_NONE="Y"
          shift 1
          ;;
        --debug)
          XC_CONFIG="Debug"
          shift 1
          ;;
        --asan)
          XC_USE_ASAN="YES"
          shift 1
          ;;
        --tsan)
          XC_USE_TSAN="YES"
          shift 1
          ;;
        --ubsan)
          XC_USE_UBSAN="YES"
          shift 1
          ;;
        --parallel-build)
          XC_USE_BCKGND="Y"
          shift 1
          ;;
        --no-parallel-build)
          XC_USE_BCKGND=""
          shift 1
          ;;
        -v)
          XC_BUILD_VERBOSITY=""
          shift 1
          ;;
        --build-spirv-tools)
          BLD_SPV_TLS="Y"
          shift 1
          ;;
        --skip-spirv-tools-build)	#deprecated
          BLD_SPV_TLS=""
          shift 1
          ;;
        --v-headers-root)
          V_HEADERS_ROOT=$2
          shift 2
          ;;
        --spirv-cross-root)
          SPIRV_CROSS_ROOT=$2
          shift 2
          ;;
        --glslang-root)
          GLSLANG_ROOT=$2
          shift 2
          ;;
        -*|--*=)
          echo "Error: Unsupported option $1" >&2
          exit 1
          ;;
   esac
 done

 # Update a repository. If it exists, fetch it; if not, clone it.
 # $1 repo name
 # $2 repo url
 # $3 repo revision (commit SHA)
 function update_repo() {
 	echo "$1 repo: $2"
 	echo "$1 revision: $3"

 	if [ -d $1 -a -d $1/.git ]; then
 		cd $1
 		git fetch --all
 		git checkout --force $3
 		cd -  > /dev/null
 	else
 		rm -rf $1
 		git clone $2 $1
 		cd $1
 		git checkout $3
 		cd -  > /dev/null
 	fi
 }

 # Build a repository
 # $1 repo name
 function build_repo() {
 	echo "Building $1"

 	mkdir -p $1/build
 	cd $1/build
 	if type ninja >/dev/null 2>&1 ; then
 		cmake -G Ninja -D CMAKE_BUILD_TYPE=Release -D CMAKE_INSTALL_PREFIX=install ..
 		ninja
 	else
 		cmake -D CMAKE_BUILD_TYPE=Release -D CMAKE_INSTALL_PREFIX=install ..
 		make -j $(sysctl -n hw.activecpu)
 	fi

 	cd -  > /dev/null
 }


 # ----------------- Main -------------------

 EXT_DIR=External
 EXT_REV_DIR=../ExternalRevisions

 echo
 echo ========== Retrieving MoltenVK dependencies into ${EXT_DIR} ==========

 mkdir -p ${EXT_DIR}
 cd ${EXT_DIR}


 # ----------------- Cereal -------------------

 echo
 echo ========== Cereal ==========
 echo

 REPO_NAME=cereal
 REPO_URL="https://github.com/USCiLab/${REPO_NAME}.git"
 REPO_REV=$(cat "${EXT_REV_DIR}/${REPO_NAME}_repo_revision")

 update_repo ${REPO_NAME} ${REPO_URL} ${REPO_REV}


 # ----------------- Vulkan-Headers -------------------

 echo
 echo ========== Vulkan-Headers ==========
 echo

 # When MoltenVK is built by something that already has
 # a copy of this repo, use it by creating a symlink.

 REPO_NAME=Vulkan-Headers

 if [ ! "$V_HEADERS_ROOT" = "" ]; then
 	rm -rf ${REPO_NAME}
 	ln -sfn ${V_HEADERS_ROOT} ${REPO_NAME}
 else
 	REPO_URL="https://github.com/KhronosGroup/${REPO_NAME}.git"
 	REPO_REV=$(cat "${EXT_REV_DIR}/${REPO_NAME}_repo_revision")

 	update_repo ${REPO_NAME} ${REPO_URL} ${REPO_REV}
 fi


 # ----------------- SPIRV-Cross -------------------

 echo
 echo ========== SPIRV-Cross ==========
 echo

 # When MoltenVK is built by something that already has
 # a copy of this repo, use it by creating a symlink.

 REPO_NAME=SPIRV-Cross

 if [ ! "$SPIRV_CROSS_ROOT" = "" ]; then
 	rm -rf ${REPO_NAME}
 	ln -sfn ${SPIRV_CROSS_ROOT} ${REPO_NAME}
 else
 	REPO_URL="https://github.com/KhronosGroup/${REPO_NAME}.git"
 	REPO_REV=$(cat "${EXT_REV_DIR}/${REPO_NAME}_repo_revision")

 	update_repo ${REPO_NAME} ${REPO_URL} ${REPO_REV}
 fi


 # ----------------- glslang -------------------

 echo
 echo ========== glslang and SPIRV-Tools ==========
 echo

 # When MoltenVK is built by something that already has
 # a copy of this repo, use it by creating a symlink.

 REPO_NAME=glslang

 if [ ! "$GLSLANG_ROOT" = "" ]; then
 	rm -rf ${REPO_NAME}
 	ln -sfn ${GLSLANG_ROOT} ${REPO_NAME}
 else
 	REPO_URL="https://github.com/KhronosGroup/${REPO_NAME}.git"
 	REPO_REV=$(cat "${EXT_REV_DIR}/${REPO_NAME}_repo_revision")

 	update_repo ${REPO_NAME} ${REPO_URL} ${REPO_REV}

 	cd ${REPO_NAME}
 	./update_glslang_sources.py
 	rm -rf build
 	./build_info.py .        \
 		-i build_info.h.tmpl  \
 		-o build/include/glslang/build_info.h
 	cd -  > /dev/null
 fi

 # Build the embedded spirv-tools, or use option of pre-generated headers
 SPV_TLS_DIR="${REPO_NAME}/External/spirv-tools"
 if [ "$BLD_SPV_TLS" = "Y" ]; then
 	build_repo "${SPV_TLS_DIR}"
 else
 	unzip -o -q -d "${SPV_TLS_DIR}" ../Templates/spirv-tools/build.zip
 	rm -rf "${SPV_TLS_DIR}/__MACOSX"
 fi


 # ----------------- Vulkan-Tools -------------------

 echo
 echo ========== Vulkan-Tools ==========
 echo

 REPO_NAME=Vulkan-Tools
 REPO_URL="https://github.com/KhronosGroup/${REPO_NAME}.git"
 REPO_REV=$(cat "${EXT_REV_DIR}/${REPO_NAME}_repo_revision")

 update_repo ${REPO_NAME} ${REPO_URL} ${REPO_REV}


 # ----------------- Cleanup -------------------

 cd ..


 # -------------- Build MoltenVK external library dependencies -----------------

 echo
 echo ========== Started building dependency libraries at `date +"%r"` ==========
 echo Please be patient on first build

 function execute_xcodebuild_command () {
 	if [ -n "${XCPRETTY}" ]; then
 		set -o pipefail && xcodebuild "$@" | tee -a "dependenciesbuild.log" | ${XCPRETTY}
 	else
 		xcodebuild "$@"
 	fi
 }

 # Build an Xcode scheme for an OS and platform
 # 1 - OS
 # 2 - Platform
 # 3 - Destination (Optional. Defaults to same as platform)
 function build_impl() {
     BLD_SPECIFIED="Y"
 	XC_OS=${1}
 	XC_PLTFM=${2}
 	if [ "${3}" != "" ]; then
 		XC_DEST=${3};
 	else
 		XC_DEST=${XC_PLTFM};
 	fi

 	XC_SCHEME="${EXT_DEPS}-${XC_OS}"
 	XC_LCL_DD_PATH="${XC_DD_PATH}/Intermediates/${XC_PLTFM}"

 	echo Building external libraries for platform ${XC_PLTFM} and destination ${XC_DEST}

 	execute_xcodebuild_command 									\
 		-project "${XC_PROJ}"									\
 		-scheme "${XC_SCHEME}"									\
 		-destination "generic/platform=${XC_DEST}"				\
 		-configuration "${XC_CONFIG}"							\
 		-enableAddressSanitizer "${XC_USE_ASAN}"				\
 		-enableThreadSanitizer "${XC_USE_TSAN}"					\
 		-enableUndefinedBehaviorSanitizer "${XC_USE_UBSAN}"		\
 		-derivedDataPath "${XC_LCL_DD_PATH}"					\
 		${XC_BUILD_VERBOSITY}									\
 		build

 	echo Completed building external libraries for ${XC_PLTFM}
 }

 # Select whether or not to run the build in parallel.
 # 1 - OS
 # 2 - platform
 function build() {
 	if [ "$XC_USE_BCKGND" != "" ]; then
 		build_impl "${1}" "${2}" "${3}" &
 	else
 		build_impl "${1}" "${2}" "${3}"
 	fi
 }

 EXT_DEPS=ExternalDependencies
 XC_PROJ="${EXT_DEPS}.xcodeproj"
 XC_DD_PATH="${EXT_DIR}/build"

 # Determine if xcpretty is present
 XCPRETTY_PATH=$(command -v xcpretty 2> /dev/null || true) # ignore failures

 # If xcpretty is present, use it to format xcodebuild output
 XCPRETTY=""
 if [ -n "$XCPRETTY_PATH" ]; then
 	XCPRETTY="xcpretty -c"
 fi
 if [ "$XC_USE_BCKGND" != "" ]; then
 	# For now, avoid using xcpretty if parallel background tasks are being used
 	XCPRETTY=""
 fi

 # Structure build tasks by platform so they can be built in parallel per platform.
 # Content for each platform must be built in series to avoid
 if [ "$XC_USE_BCKGND" != "" ]; then
 	trap "exit" INT TERM ERR
 	trap "kill 0" EXIT
 fi

 if [ "$BLD_MACOS" != "" ]; then
 	build "macOS" "macOS"
 fi

 if [ "$BLD_IOS" != "" ]; then
 	build "iOS" "iOS"
 fi

 if [ "$BLD_IOS_SIM" != "" ]; then
 	build "iOS" "iOS Simulator"
 fi

 if [ "$BLD_MAC_CAT" != "" ]; then
 	build "iOS" "Mac Catalyst" "macOS,variant=Mac Catalyst"
 fi

 if [ "$BLD_TVOS" != "" ]; then
 	build "tvOS" "tvOS"
 fi

 if [ "$BLD_TVOS_SIM" != "" ]; then
 	build "tvOS" "tvOS Simulator"
 fi

 # Wait for any background process (if selected) to finish
 if [ "$XC_USE_BCKGND" != "" ]; then
 	wait
 fi

 if [ "$BLD_SPECIFIED" != "" ]; then
 	# Build XCFrameworks, update latest symlink, and clean MoltenVK for rebuild
 	PROJECT_DIR="."
 	CONFIGURATION=${XC_CONFIG}
 	. "./Scripts/create_ext_lib_xcframeworks.sh"
 	. "./Scripts/package_ext_libs_finish.sh"
 else
 	if [ "$BLD_NONE" != "" ]; then
 		echo Not building any platforms
 	else
 		echo "WARNING: You did not specify a platform to build."
 		echo "To build the external libraries, include one or"
 		echo "more of the following platform options:"
 		echo "    --macos --ios --iossim --maccat --tvos --tvossim --all"
 		echo "See the instructions in the fetchDependencies script for more info."
 	fi
 fi

 echo ========== Finished at `date +"%r"` ==========
 exit 0
	#!/bin/bash
	#
	# Copyright (c) 2016-2022 The Brenwill Workshop Ltd.
	#
	# fetchDependencies - Retrieves the correct versions of all dependencies
	#
	# macOS usage: ./fetchDependencies [--macos] [--ios] [--iossim] [--tvos] [--tvossim] [--all] [--none]
	# [-v] [--debug] [--build-spirv-tools]
	# [--v-headers-root path] [--spirv-cross-root path] [--glslang-root path]
	#
	# --macos
	# Build the external libraries for the macOS platform.
	#
	# --ios
	# Build the external libraries for the iOS platform.
	#
	# --iossim
	# Build the external libraries for the iOS Simulator platform.
	#
	# --maccat
	# Build the external libraries for the Mac Catalyst platform.
	#
	# --tvos
	# Build the external libraries for the tvOS platform.
	#
	# --tvossim
	# Build the external libraries for the tvOS Simulator platform.
	#
	# --all
	# Equivalent to specifying [--macos --ios --iossim --maccat --tvos --tvossim].
	# Results in one XCFramework for each external library, each containing
	# binaries for all supported platforms.
	#
	# --none
	# Don't build the external libraries for any platform (this is the default).
	#
	# Multiple platform options may be specified. At least one platform option must be specified.
	#
	# --asan
	# Build the external libraries against Address Sanitizer, which may be useful when debugging
	# and tracing calls into those libraries.
	#
	# --tsan
	# Build the external libraries against Thread Sanitizer, which may be useful when debugging
	# and tracing calls into those libraries.
	#
	# --ubsan
	# Build the external libraries against Undefined Behavior Sanitizer, which may be useful when debugging
	# and tracing calls into those libraries.
	#
	# --debug
	# Build the external libraries in Debug mode, which may be useful when debugging
	# and tracing calls into those libraries.
	#
	# --parallel-build
	# Build the external libraries in parallel using background processes.
	#
	# --no-parallel-build
	# Build the external libraries serially instead of in parallel. This is the default.
	#
	# --glslang-root path
	# "path" specifies a directory path to a KhronosGroup/glslang repository.
	# This repository does need to be built and the build directory must be in the
	# specified directory. It should be built the same way this script builds it.
	#
	# --build-spirv-tools
	# Build the full spirv-tools distribution. Normally this is not needed, because
	# MoltenVK includes a template of pre-generated SPIRV-Tools header files, which
	# is all that is needed. Avoiding the spirv-tools build saves significant time
	# during the running of this script, and is necessary during CI because Travis CI
	# cannot support the required use of Python3 by the spirv-tools build. This flag
	# is used by the packagePregenSpirvToolsHeaders script which regenerates the
	# spirv-tools header files and repackages the Templates/spirv-tools/build.zip
	# file when the spirv-tools library version is upgraded.
	#
	# --spirv-cross-root path
	# "path" specifies a directory path to a KhronosGroup/SPIRV-Cross repository.
	# This repository does not have to be built.
	#
	# -v verbose output
	#
	# --v-headers-root path
	# "path" specifies a directory path to a KhronosGroup/Vulkan-Headers repository.
	# This repository does not have to be built.
	#

	set -e

	# ----------------- Functions -------------------

	BLD_NONE=""
	BLD_IOS=""
	BLD_IOS_SIM=""
	BLD_MAC_CAT=""
	BLD_TVOS=""
	BLD_TVOS_SIM=""
	BLD_MACOS=""
	BLD_SPECIFIED=""
	XC_CONFIG="Release"
	XC_BUILD_VERBOSITY="-quiet"
	XC_USE_BCKGND=""
	XC_USE_ASAN="NO"
	XC_USE_TSAN="NO"
	XC_USE_UBSAN="NO"
	V_HEADERS_ROOT=""
	SPIRV_CROSS_ROOT=""
	GLSLANG_ROOT=""
	BLD_SPV_TLS=""

	while (( "$#" )); do
	case "$1" in
	--ios)
	BLD_IOS="Y"
	shift 1
	;;
	--iossim)
	BLD_IOS_SIM="Y"
	shift 1
	;;
	--maccat)
	BLD_MAC_CAT="Y"
	shift 1
	;;
	--tvos)
	BLD_TVOS="Y"
	shift 1
	;;
	--tvossim)
	BLD_TVOS_SIM="Y"
	shift 1
	;;
	--macos)
	BLD_MACOS="Y"
	shift 1
	;;
	--all)
	BLD_IOS="Y"
	BLD_IOS_SIM="Y"
	BLD_MAC_CAT="Y"
	BLD_TVOS="Y"
	BLD_TVOS_SIM="Y"
	BLD_MACOS="Y"
	shift 1
	;;
	--none)
	BLD_NONE="Y"
	shift 1
	;;
	--debug)
	XC_CONFIG="Debug"
	shift 1
	;;
	--asan)
	XC_USE_ASAN="YES"
	shift 1
	;;
	--tsan)
	XC_USE_TSAN="YES"
	shift 1
	;;
	--ubsan)
	XC_USE_UBSAN="YES"
	shift 1
	;;
	--parallel-build)
	XC_USE_BCKGND="Y"
	shift 1
	;;
	--no-parallel-build)
	XC_USE_BCKGND=""
	shift 1
	;;
	-v)
	XC_BUILD_VERBOSITY=""
	shift 1
	;;
	--build-spirv-tools)
	BLD_SPV_TLS="Y"
	shift 1
	;;
	--skip-spirv-tools-build) #deprecated
	BLD_SPV_TLS=""
	shift 1
	;;
	--v-headers-root)
	V_HEADERS_ROOT=$2
	shift 2
	;;
	--spirv-cross-root)
	SPIRV_CROSS_ROOT=$2
	shift 2
	;;
	--glslang-root)
	GLSLANG_ROOT=$2
	shift 2
	;;
	-\|--=)
	echo "Error: Unsupported option $1" >&2
	exit 1
	;;
	esac
	done

	# Update a repository. If it exists, fetch it; if not, clone it.
	# $1 repo name
	# $2 repo url
	# $3 repo revision (commit SHA)
	function update_repo() {
	echo "$1 repo: $2"
	echo "$1 revision: $3"

	if [ -d $1 -a -d $1/.git ]; then
	cd $1
	git fetch --all
	git checkout --force $3
	cd - > /dev/null
	else
	rm -rf $1
	git clone $2 $1
	cd $1
	git checkout $3
	cd - > /dev/null
	fi
	}

	# Build a repository
	# $1 repo name
	function build_repo() {
	echo "Building $1"

	mkdir -p $1/build
	cd $1/build
	if type ninja >/dev/null 2>&1 ; then
	cmake -G Ninja -D CMAKE_BUILD_TYPE=Release -D CMAKE_INSTALL_PREFIX=install ..
	ninja
	else
	cmake -D CMAKE_BUILD_TYPE=Release -D CMAKE_INSTALL_PREFIX=install ..
	make -j $(sysctl -n hw.activecpu)
	fi

	cd - > /dev/null
	}


	# ----------------- Main -------------------

	EXT_DIR=External
	EXT_REV_DIR=../ExternalRevisions

	echo
	echo ========== Retrieving MoltenVK dependencies into ${EXT_DIR} ==========

	mkdir -p ${EXT_DIR}
	cd ${EXT_DIR}


	# ----------------- Cereal -------------------

	echo
	echo ========== Cereal ==========
	echo

	REPO_NAME=cereal
	REPO_URL="https://github.com/USCiLab/${REPO_NAME}.git"
	REPO_REV=$(cat "${EXT_REV_DIR}/${REPO_NAME}_repo_revision")

	update_repo ${REPO_NAME} ${REPO_URL} ${REPO_REV}


	# ----------------- Vulkan-Headers -------------------

	echo
	echo ========== Vulkan-Headers ==========
	echo

	# When MoltenVK is built by something that already has
	# a copy of this repo, use it by creating a symlink.

	REPO_NAME=Vulkan-Headers

	if [ ! "$V_HEADERS_ROOT" = "" ]; then
	rm -rf ${REPO_NAME}
	ln -sfn ${V_HEADERS_ROOT} ${REPO_NAME}
	else
	REPO_URL="https://github.com/KhronosGroup/${REPO_NAME}.git"
	REPO_REV=$(cat "${EXT_REV_DIR}/${REPO_NAME}_repo_revision")

	update_repo ${REPO_NAME} ${REPO_URL} ${REPO_REV}
	fi


	# ----------------- SPIRV-Cross -------------------

	echo
	echo ========== SPIRV-Cross ==========
	echo

	# When MoltenVK is built by something that already has
	# a copy of this repo, use it by creating a symlink.

	REPO_NAME=SPIRV-Cross

	if [ ! "$SPIRV_CROSS_ROOT" = "" ]; then
	rm -rf ${REPO_NAME}
	ln -sfn ${SPIRV_CROSS_ROOT} ${REPO_NAME}
	else
	REPO_URL="https://github.com/KhronosGroup/${REPO_NAME}.git"
	REPO_REV=$(cat "${EXT_REV_DIR}/${REPO_NAME}_repo_revision")

	update_repo ${REPO_NAME} ${REPO_URL} ${REPO_REV}
	fi



	# ----------------- glslang -------------------

	echo
	echo ========== glslang and SPIRV-Tools ==========
	echo

	# When MoltenVK is built by something that already has
	# a copy of this repo, use it by creating a symlink.

	REPO_NAME=glslang

	if [ ! "$GLSLANG_ROOT" = "" ]; then
	rm -rf ${REPO_NAME}
	ln -sfn ${GLSLANG_ROOT} ${REPO_NAME}
	else
	REPO_URL="https://github.com/KhronosGroup/${REPO_NAME}.git"
	REPO_REV=$(cat "${EXT_REV_DIR}/${REPO_NAME}_repo_revision")

	update_repo ${REPO_NAME} ${REPO_URL} ${REPO_REV}

	cd ${REPO_NAME}
	./update_glslang_sources.py
	rm -rf build
	./build_info.py . \
	-i build_info.h.tmpl \
	-o build/include/glslang/build_info.h
	cd - > /dev/null
	fi

	# Build the embedded spirv-tools, or use option of pre-generated headers
	SPV_TLS_DIR="${REPO_NAME}/External/spirv-tools"
	if [ "$BLD_SPV_TLS" = "Y" ]; then
	build_repo "${SPV_TLS_DIR}"
	else
	unzip -o -q -d "${SPV_TLS_DIR}" ../Templates/spirv-tools/build.zip
	rm -rf "${SPV_TLS_DIR}/__MACOSX"
	fi



	# ----------------- Vulkan-Tools -------------------

	echo
	echo ========== Vulkan-Tools ==========
	echo

	REPO_NAME=Vulkan-Tools
	REPO_URL="https://github.com/KhronosGroup/${REPO_NAME}.git"
	REPO_REV=$(cat "${EXT_REV_DIR}/${REPO_NAME}_repo_revision")

	update_repo ${REPO_NAME} ${REPO_URL} ${REPO_REV}


	# ----------------- Cleanup -------------------

	cd ..


	# -------------- Build MoltenVK external library dependencies -----------------

	echo
	echo ========== Started building dependency libraries at `date +"%r"` ==========
	echo Please be patient on first build

	function execute_xcodebuild_command () {
	if [ -n "${XCPRETTY}" ]; then
	set -o pipefail && xcodebuild "$@" \| tee -a "dependenciesbuild.log" \| ${XCPRETTY}
	else
	xcodebuild "$@"
	fi
	}

	# Build an Xcode scheme for an OS and platform
	# 1 - OS
	# 2 - Platform
	# 3 - Destination (Optional. Defaults to same as platform)
	function build_impl() {
	BLD_SPECIFIED="Y"
	XC_OS=${1}
	XC_PLTFM=${2}
	if [ "${3}" != "" ]; then
	XC_DEST=${3};
	else
	XC_DEST=${XC_PLTFM};
	fi

	XC_SCHEME="${EXT_DEPS}-${XC_OS}"
	XC_LCL_DD_PATH="${XC_DD_PATH}/Intermediates/${XC_PLTFM}"

	echo Building external libraries for platform ${XC_PLTFM} and destination ${XC_DEST}

	execute_xcodebuild_command \
	-project "${XC_PROJ}" \
	-scheme "${XC_SCHEME}" \
	-destination "generic/platform=${XC_DEST}" \
	-configuration "${XC_CONFIG}" \
	-enableAddressSanitizer "${XC_USE_ASAN}" \
	-enableThreadSanitizer "${XC_USE_TSAN}" \
	-enableUndefinedBehaviorSanitizer "${XC_USE_UBSAN}" \
	-derivedDataPath "${XC_LCL_DD_PATH}" \
	${XC_BUILD_VERBOSITY} \
	build

	echo Completed building external libraries for ${XC_PLTFM}
	}

	# Select whether or not to run the build in parallel.
	# 1 - OS
	# 2 - platform
	function build() {
	if [ "$XC_USE_BCKGND" != "" ]; then
	build_impl "${1}" "${2}" "${3}" &
	else
	build_impl "${1}" "${2}" "${3}"
	fi
	}

	EXT_DEPS=ExternalDependencies
	XC_PROJ="${EXT_DEPS}.xcodeproj"
	XC_DD_PATH="${EXT_DIR}/build"

	# Determine if xcpretty is present
	XCPRETTY_PATH=$(command -v xcpretty 2> /dev/null \|\| true) # ignore failures

	# If xcpretty is present, use it to format xcodebuild output
	XCPRETTY=""
	if [ -n "$XCPRETTY_PATH" ]; then
	XCPRETTY="xcpretty -c"
	fi
	if [ "$XC_USE_BCKGND" != "" ]; then
	# For now, avoid using xcpretty if parallel background tasks are being used
	XCPRETTY=""
	fi

	# Structure build tasks by platform so they can be built in parallel per platform.
	# Content for each platform must be built in series to avoid
	if [ "$XC_USE_BCKGND" != "" ]; then
	trap "exit" INT TERM ERR
	trap "kill 0" EXIT
	fi

	if [ "$BLD_MACOS" != "" ]; then
	build "macOS" "macOS"
	fi

	if [ "$BLD_IOS" != "" ]; then
	build "iOS" "iOS"
	fi

	if [ "$BLD_IOS_SIM" != "" ]; then
	build "iOS" "iOS Simulator"
	fi

	if [ "$BLD_MAC_CAT" != "" ]; then
	build "iOS" "Mac Catalyst" "macOS,variant=Mac Catalyst"
	fi

	if [ "$BLD_TVOS" != "" ]; then
	build "tvOS" "tvOS"
	fi

	if [ "$BLD_TVOS_SIM" != "" ]; then
	build "tvOS" "tvOS Simulator"
	fi

	# Wait for any background process (if selected) to finish
	if [ "$XC_USE_BCKGND" != "" ]; then
	wait
	fi

	if [ "$BLD_SPECIFIED" != "" ]; then
	# Build XCFrameworks, update latest symlink, and clean MoltenVK for rebuild
	PROJECT_DIR="."
	CONFIGURATION=${XC_CONFIG}
	. "./Scripts/create_ext_lib_xcframeworks.sh"
	. "./Scripts/package_ext_libs_finish.sh"
	else
	if [ "$BLD_NONE" != "" ]; then
	echo Not building any platforms
	else
	echo "WARNING: You did not specify a platform to build."
	echo "To build the external libraries, include one or"
	echo "more of the following platform options:"
	echo " --macos --ios --iossim --maccat --tvos --tvossim --all"
	echo "See the instructions in the fetchDependencies script for more info."
	fi
	fi

	echo ========== Finished at `date +"%r"` ==========
	exit 0