From bb15e2287f061efa3fd17faff89d16d98eedda47 Mon Sep 17 00:00:00 2001
From: Ryan Pavlik <ryan.pavlik@collabora.com>
Date: Wed, 2 Dec 2020 11:50:16 -0600
Subject: [PATCH] Modularize build system usage of dependencies.

Must check for the existence of a bundled dep before we use it,
since e.g. Debian has to strip some files for license and policy reasons.
---
 src/external/eigen.cmake                      |  18 +++
 src/external/external.cmake                   |  30 +++--
 src/external/glew.cmake                       |  50 ++++++++
 src/external/gmp-mpir.cmake                   |  48 ++++++++
 src/external/levmar-2.3/CMakeLists.txt        |  67 ++++++++---
 .../levmar-2.3/CMakeLists_original.txt        |  52 ---------
 src/external/levmar.cmake                     |  23 ++++
 .../CMakeLists.txt => lib3ds.cmake}           |  16 ++-
 .../CMakeLists.txt => muparser.cmake}         |  12 +-
 src/external/newuoa.cmake                     |  11 ++
 .../CMakeLists.txt => openctm.cmake}          |  12 +-
 src/external/opengr.cmake                     |  11 ++
 .../CMakeLists.txt => qhull.cmake}            |  12 +-
 src/external/ssynth.cmake                     | 108 ++++++++++++++++++
 .../structuresynth-1.5/CMakeLists.txt         | 101 ----------------
 src/external/u3d.cmake                        |  10 ++
 src/external/u3d/CMakeLists.txt               |   1 -
 src/external_common.cmake                     |  19 ++-
 18 files changed, 393 insertions(+), 208 deletions(-)
 create mode 100644 src/external/eigen.cmake
 create mode 100644 src/external/glew.cmake
 create mode 100644 src/external/gmp-mpir.cmake
 delete mode 100644 src/external/levmar-2.3/CMakeLists_original.txt
 create mode 100644 src/external/levmar.cmake
 rename src/external/{lib3ds-1.3.0/CMakeLists.txt => lib3ds.cmake} (74%)
 rename src/external/{muparser_v225/CMakeLists.txt => muparser.cmake} (66%)
 create mode 100644 src/external/newuoa.cmake
 rename src/external/{OpenCTM-1.0.3/CMakeLists.txt => openctm.cmake} (71%)
 create mode 100644 src/external/opengr.cmake
 rename src/external/{qhull-2003.1/CMakeLists.txt => qhull.cmake} (73%)
 create mode 100644 src/external/ssynth.cmake
 delete mode 100644 src/external/structuresynth-1.5/CMakeLists.txt
 create mode 100644 src/external/u3d.cmake

diff --git a/src/external/eigen.cmake b/src/external/eigen.cmake
new file mode 100644
index 000000000..4c75a7e93
--- /dev/null
+++ b/src/external/eigen.cmake
@@ -0,0 +1,18 @@
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
+option(ALLOW_BUNDLED_EIGEN "Allow use of bundled Eigen source" ON)
+option(ALLOW_SYSTEM_EIGEN "Allow use of system-provided Eigen" ON)
+
+if(ALLOW_SYSTEM_EIGEN AND EIGEN3_INCLUDE_DIR)
+	message(STATUS "- Eigen - using system-provided library")
+	set(EIGEN_INCLUDE_DIRS ${EIGEN3_INCLUDE_DIR})
+elseif(ALLOW_BUNDLED_EIGEN AND EXISTS "${EIGEN_DIR}/Eigen/Eigen")
+	message(STATUS "- Eigen - using bundled source")
+	set(EIGEN_INCLUDE_DIRS ${EIGEN_DIR})
+else()
+	message(
+		FATAL_ERROR
+			"Eigen is required - at least one of ALLOW_SYSTEM_EIGEN or ALLOW_BUNDLED_EIGEN must be enabled and found.")
+endif()
diff --git a/src/external/external.cmake b/src/external/external.cmake
index e329193c4..7efb0f63c 100644
--- a/src/external/external.cmake
+++ b/src/external/external.cmake
@@ -1,45 +1,43 @@
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
 # newuoa - optional and header-only, for several plugins including all that use levmar
 set(NEWUOA_DIR ${VCGDIR}/wrap/newuoa)
-message(STATUS "- newuoa - using bundled source")
-add_library(external-newuoa INTERFACE)
-target_include_directories(external-newuoa INTERFACE ${NEWUOA_DIR}/include)
+include(${EXTERNAL_DIR}/newuoa.cmake)
 
 # levmar - optional, for several plugins
 set(LEVMAR_DIR ${EXTERNAL_DIR}/levmar-2.3)
-add_subdirectory(${LEVMAR_DIR})
+include(${EXTERNAL_DIR}/levmar.cmake)
 
 # lib3ds - optional, for io_3ds
 set(LIB3DS_DIR ${EXTERNAL_DIR}/lib3ds-1.3.0)
-add_subdirectory(${LIB3DS_DIR})
+include(${EXTERNAL_DIR}/lib3ds.cmake)
 
 # gmp or mpir - optional, for filter_csg
 set(MPIR_DIR ${EXTERNAL_DIR}/mpir)
-add_subdirectory(${MPIR_DIR})
+include(${EXTERNAL_DIR}/gmp-mpir.cmake)
 
 # muparser - optional, for filter_func
 set(MUPARSER_DIR ${EXTERNAL_DIR}/muparser_v225)
-add_subdirectory(${MUPARSER_DIR})
+include(${EXTERNAL_DIR}/muparser.cmake)
 
 # OpenCTM - optional, for io_ctm
 set(OPENCTM_DIR ${EXTERNAL_DIR}/OpenCTM-1.0.3)
-add_subdirectory(${OPENCTM_DIR})
+include(${EXTERNAL_DIR}/openctm.cmake)
 
 # structure-synth - optional, for filter_ssynth
 set(SSYNTH_DIR ${EXTERNAL_DIR}/structuresynth-1.5)
-add_subdirectory(${SSYNTH_DIR})
+include(${EXTERNAL_DIR}/ssynth.cmake)
 
 # qhull - optional, for filter_qhull
 set(QHULL_DIR ${EXTERNAL_DIR}/qhull-2003.1)
-add_subdirectory(${QHULL_DIR})
+include(${EXTERNAL_DIR}/qhull.cmake)
 
 # u3d - optional, for io_u3d
 set(U3D_DIR ${EXTERNAL_DIR}/u3d)
-add_subdirectory(${U3D_DIR})
-#set_property(TARGET external-IDTFConverter PROPERTY FOLDER External)
+include(${EXTERNAL_DIR}/u3d.cmake)
 
 # opengr - optional and header-only, for filter_globalregistration
 set(OPENGR_DIR ${EXTERNAL_DIR}/OpenGR)
-message(STATUS "- OpenGR - using bundled source")
-add_library(external-opengr INTERFACE)
-target_include_directories(external-opengr INTERFACE ${OPENGR_DIR}/src/)
-
+include(${EXTERNAL_DIR}/opengr.cmake)
diff --git a/src/external/glew.cmake b/src/external/glew.cmake
new file mode 100644
index 000000000..0e308d9eb
--- /dev/null
+++ b/src/external/glew.cmake
@@ -0,0 +1,50 @@
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
+option(ALLOW_BUNDLED_GLEW "Allow use of bundled GLEW source" ON)
+option(ALLOW_SYSTEM_GLEW "Allow use of system-provided GLEW" ON)
+
+unset(HAVE_SYSTEM_GLEW)
+if(DEFINED GLEW_VERSION)
+	if((TARGET GLEW::GLEW) AND (${GLEW_VERSION} VERSION_GREATER_EQUAL "2.0.0"))
+		set(HAVE_SYSTEM_GLEW TRUE)
+	endif()
+endif()
+
+if(ALLOW_SYSTEM_GLEW AND HAVE_SYSTEM_GLEW)
+	message(STATUS "- glew - using system-provided library")
+	add_library(external-glew INTERFACE)
+	target_link_libraries(external-glew INTERFACE GLEW::GLEW)
+	if(TARGET OpenGL::OpenGL)
+		target_link_libraries(external-glew INTERFACE OpenGL::OpenGL)
+	elseif(TARGET OpenGL::GL)
+		target_link_libraries(external-glew INTERFACE OpenGL::GL)
+	else()
+		message(FATAL_ERROR "OpenGL not found or your CMake version is too old!")
+	endif()
+elseif(ALLOW_BUNDLED_GLEW AND EXISTS "${GLEW_DIR}/src/glew.c")
+	message(STATUS "- glew - using bundled source")
+	add_library(external-glew STATIC "${GLEW_DIR}/src/glew.c")
+	target_compile_definitions(external-glew PUBLIC GLEW_STATIC)
+	target_include_directories(external-glew SYSTEM PUBLIC ${GLEW_DIR}/include)
+	if(TARGET OpenGL::OpenGL)
+		target_link_libraries(external-glew PUBLIC OpenGL::OpenGL)
+	elseif(TARGET OpenGL::GL)
+		target_link_libraries(external-glew PUBLIC OpenGL::GL)
+	else()
+		message(FATAL_ERROR "OpenGL not found or your CMake version is too old!")
+	endif()
+	if(TARGET OpenGL::GLX)
+		target_link_libraries(external-glew PUBLIC OpenGL::GLX)
+	endif()
+	set_property(TARGET external-glew PROPERTY FOLDER External)
+
+	# TODO not sure what this was for, but it's almost certainly wrong on at least one compiler
+	# since it's not in a compiler conditional.
+	# target_compile_options(external-glew PRIVATE -w)
+else()
+	message(
+		FATAL_ERROR
+			"GLEW is required - at least one of ALLOW_SYSTEM_GLEW or ALLOW_BUNDLED_GLEW must be enabled and found.")
+endif()
diff --git a/src/external/gmp-mpir.cmake b/src/external/gmp-mpir.cmake
new file mode 100644
index 000000000..ae757716c
--- /dev/null
+++ b/src/external/gmp-mpir.cmake
@@ -0,0 +1,48 @@
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
+option(ALLOW_SYSTEM_GMP "Allow use of system-provided GMP" ON)
+option(ALLOW_BUNDLED_MPIR "Allow use of bundled MPIR binaries" ON)
+
+unset(HAVE_BUNDLED_MPIR)
+if (APPLE AND EXISTS "${MPIR_DIR}/macx64/libmpir.a" AND CMAKE_SIZEOF_VOID_P EQUAL 8)
+	# We have mac binaries for x64
+	# TODO check target processor architecture, not just pointer size
+	set(HAVE_BUNDLED_MPIR APPLE-x64)
+elseif(WIN32 AND MSVC AND EXISTS "${MPIR_DIR}/win32-msvc/mpir.lib" AND CMAKE_SIZEOF_VOID_P EQUAL 8)
+	# We have windows binaries for x64
+	# TODO check target processor architecture, not just pointer size
+	set(HAVE_BUNDLED_MPIR WIN-x64)
+endif()
+
+# gmp or mpir - optional, for filter_csg
+if(ALLOW_SYSTEM_GMP AND GMP_FOUND)
+	message(STATUS "- GMP/MPIR - using system-provided GMP library")
+	add_library(external-gmp INTERFACE)
+	target_include_directories(external-gmp SYSTEM INTERFACE ${GMP_INCLUDE_DIRS})
+	target_link_libraries(external-gmp INTERFACE ${GMP_LIBRARIES})
+
+elseif(ALLOW_BUNDLED_MPIR AND HAVE_BUNDLED_MPIR)
+	message(STATUS "- GMP/MPIR - using already built MPIR library")
+	add_library(external-mpir SHARED IMPORTED GLOBAL)
+	add_library(external-mpirxx SHARED IMPORTED GLOBAL)
+	# TODO why are we copying these? They're static libraries, not needed at runtime.
+	if (HAVE_BUNDLED_MPIR STREQUAL "WIN-x64")
+		file(
+			COPY ${MPIR_DIR}/win32-msvc/mpir.lib ${MPIR_DIR}/win32-msvc/mpirxx.lib
+			DESTINATION ${MESHLAB_LIB_OUTPUT_DIR})
+		set_property(TARGET external-mpir PROPERTY IMPORTED_IMPLIB "${MESHLAB_LIB_OUTPUT_DIR}/mpir.lib")
+		set_property(TARGET external-mpir PROPERTY IMPORTED_LOCATION "${MESHLAB_LIB_OUTPUT_DIR}/mpir.lib")
+		set_property(TARGET external-mpirxx PROPERTY IMPORTED_IMPLIB "${MESHLAB_LIB_OUTPUT_DIR}/mpirxx.lib")
+		set_property(TARGET external-mpirxx PROPERTY IMPORTED_LOCATION "${MESHLAB_LIB_OUTPUT_DIR}/mpirxx.lib")
+		target_include_directories(external-mpir INTERFACE ${EXTERNAL_DIR}/inc/win32-msvc/mpir-2.2.1_x64)
+	elseif(HAVE_BUNDLED_MPIR STREQUAL "APPLE-x64")
+		file(
+			COPY ${MPIR_DIR}/macx64/libmpir.a ${MPIR_DIR}/macx64/libmpirxx.a
+			DESTINATION ${MESHLAB_LIB_OUTPUT_DIR})
+		set_property(TARGET external-mpir PROPERTY IMPORTED_LOCATION "${MESHLAB_LIB_OUTPUT_DIR}/libmpir.a")
+		set_property(TARGET external-mpirxx PROPERTY IMPORTED_LOCATION "${MESHLAB_LIB_OUTPUT_DIR}/libmpirxx.a")
+		target_include_directories(external-mpir INTERFACE ${EXTERNAL_DIR}/inc/macx64/mpir-2.4.0)
+	endif()
+endif()
diff --git a/src/external/levmar-2.3/CMakeLists.txt b/src/external/levmar-2.3/CMakeLists.txt
index f9ebfba91..0ba255c15 100644
--- a/src/external/levmar-2.3/CMakeLists.txt
+++ b/src/external/levmar-2.3/CMakeLists.txt
@@ -1,15 +1,52 @@
-message(STATUS "- levmar - using bundled source")
-add_library(
-	external-levmar STATIC
-	"${LEVMAR_DIR}/compiler.h"
-	"${LEVMAR_DIR}/lm.h"
-	"${LEVMAR_DIR}/misc.h"
-	"${LEVMAR_DIR}/Axb.c"
-	"${LEVMAR_DIR}/lm.c"
-	"${LEVMAR_DIR}/lmbc.c"
-	"${LEVMAR_DIR}/lmblec.c"
-	"${LEVMAR_DIR}/lmlec.c"
-	"${LEVMAR_DIR}/misc.c")
-target_include_directories(external-levmar PUBLIC ${LEVMAR_DIR})
-set_property(TARGET external-levmar PROPERTY FOLDER External)
-target_compile_options(external-levmar PRIVATE -w)
+# levmar CMake file; see http://www.cmake.org and 
+#                        http://www.insightsoftwareconsortium.org/wiki/index.php/CMake_Tutorial
+
+PROJECT(LEVMAR)
+#CMAKE_MINIMUM_REQUIRED(VERSION 1.4)
+
+# compiler flags
+ADD_DEFINITIONS(-DLINSOLVERS_RETAIN_MEMORY) # do not free memory between linear solvers calls
+#REMOVE_DEFINITIONS(-DLINSOLVERS_RETAIN_MEMORY)
+
+# f2c is sometimes equivalent to libF77 & libI77; in that case, set HAVE_F2C to 0
+SET(HAVE_F2C 1 CACHE BOOL "Do we have f2c or F77/I77?" )
+
+# the directory where the lapack/blas/f2c libraries reside
+SET(LAPACKBLAS_DIR /usr/lib CACHE PATH "Path to lapack/blas libraries")
+
+# actual names for the lapack/blas/f2c libraries
+SET(LAPACK_LIB lapack CACHE STRING "The name of the lapack library")
+SET(BLAS_LIB blas CACHE STRING "The name of the blas library")
+IF(HAVE_F2C)
+  SET(F2C_LIB f2c CACHE STRING "The name of the f2c library")
+ELSE(HAVE_F2C)
+  SET(F77_LIB libF77 CACHE STRING "The name of the F77 library")
+  SET(I77_LIB libI77 CACHE STRING "The name of the I77 library")
+ENDIF(HAVE_F2C)
+
+########################## NO CHANGES BEYOND THIS POINT ##########################
+
+#INCLUDE_DIRECTORIES(/usr/include)
+LINK_DIRECTORIES(${LAPACKBLAS_DIR})
+
+# levmar library source files
+ADD_LIBRARY(levmar STATIC
+  lm.c Axb.c misc.c lmlec.c lmbc.c lmblec.c
+  lm.h misc.h compiler.h
+)
+
+# demo program
+ADD_EXECUTABLE(lmdemo lmdemo.c lm.h)
+# libraries the demo depends on
+IF(HAVE_F2C)
+  TARGET_LINK_LIBRARIES(lmdemo levmar ${LAPACK_LIB} ${BLAS_LIB} ${F2C_LIB})
+ELSE(HAVE_F2C)
+  TARGET_LINK_LIBRARIES(lmdemo levmar ${LAPACK_LIB} ${BLAS_LIB} ${F77_LIB} ${I77_LIB})
+ENDIF(HAVE_F2C)
+
+# make sure that the library is built before the demo
+ADD_DEPENDENCIES(lmdemo levmar)
+
+#SUBDIRS(matlab)
+
+#ADD_TEST(levmar_tst lmdemo)
diff --git a/src/external/levmar-2.3/CMakeLists_original.txt b/src/external/levmar-2.3/CMakeLists_original.txt
deleted file mode 100644
index 0ba255c15..000000000
--- a/src/external/levmar-2.3/CMakeLists_original.txt
+++ /dev/null
@@ -1,52 +0,0 @@
-# levmar CMake file; see http://www.cmake.org and 
-#                        http://www.insightsoftwareconsortium.org/wiki/index.php/CMake_Tutorial
-
-PROJECT(LEVMAR)
-#CMAKE_MINIMUM_REQUIRED(VERSION 1.4)
-
-# compiler flags
-ADD_DEFINITIONS(-DLINSOLVERS_RETAIN_MEMORY) # do not free memory between linear solvers calls
-#REMOVE_DEFINITIONS(-DLINSOLVERS_RETAIN_MEMORY)
-
-# f2c is sometimes equivalent to libF77 & libI77; in that case, set HAVE_F2C to 0
-SET(HAVE_F2C 1 CACHE BOOL "Do we have f2c or F77/I77?" )
-
-# the directory where the lapack/blas/f2c libraries reside
-SET(LAPACKBLAS_DIR /usr/lib CACHE PATH "Path to lapack/blas libraries")
-
-# actual names for the lapack/blas/f2c libraries
-SET(LAPACK_LIB lapack CACHE STRING "The name of the lapack library")
-SET(BLAS_LIB blas CACHE STRING "The name of the blas library")
-IF(HAVE_F2C)
-  SET(F2C_LIB f2c CACHE STRING "The name of the f2c library")
-ELSE(HAVE_F2C)
-  SET(F77_LIB libF77 CACHE STRING "The name of the F77 library")
-  SET(I77_LIB libI77 CACHE STRING "The name of the I77 library")
-ENDIF(HAVE_F2C)
-
-########################## NO CHANGES BEYOND THIS POINT ##########################
-
-#INCLUDE_DIRECTORIES(/usr/include)
-LINK_DIRECTORIES(${LAPACKBLAS_DIR})
-
-# levmar library source files
-ADD_LIBRARY(levmar STATIC
-  lm.c Axb.c misc.c lmlec.c lmbc.c lmblec.c
-  lm.h misc.h compiler.h
-)
-
-# demo program
-ADD_EXECUTABLE(lmdemo lmdemo.c lm.h)
-# libraries the demo depends on
-IF(HAVE_F2C)
-  TARGET_LINK_LIBRARIES(lmdemo levmar ${LAPACK_LIB} ${BLAS_LIB} ${F2C_LIB})
-ELSE(HAVE_F2C)
-  TARGET_LINK_LIBRARIES(lmdemo levmar ${LAPACK_LIB} ${BLAS_LIB} ${F77_LIB} ${I77_LIB})
-ENDIF(HAVE_F2C)
-
-# make sure that the library is built before the demo
-ADD_DEPENDENCIES(lmdemo levmar)
-
-#SUBDIRS(matlab)
-
-#ADD_TEST(levmar_tst lmdemo)
diff --git a/src/external/levmar.cmake b/src/external/levmar.cmake
new file mode 100644
index 000000000..6b7074cf7
--- /dev/null
+++ b/src/external/levmar.cmake
@@ -0,0 +1,23 @@
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
+option(ALLOW_BUNDLED_LEVMAR "Allow use of bundled levmar source" ON)
+
+if(ALLOW_BUNDLED_LEVMAR AND EXISTS "${LEVMAR_DIR}/lm.h")
+	message(STATUS "- levmar - using bundled source")
+	add_library(
+		external-levmar STATIC
+		"${LEVMAR_DIR}/compiler.h"
+		"${LEVMAR_DIR}/lm.h"
+		"${LEVMAR_DIR}/misc.h"
+		"${LEVMAR_DIR}/Axb.c"
+		"${LEVMAR_DIR}/lm.c"
+		"${LEVMAR_DIR}/lmbc.c"
+		"${LEVMAR_DIR}/lmblec.c"
+		"${LEVMAR_DIR}/lmlec.c"
+		"${LEVMAR_DIR}/misc.c")
+	target_include_directories(external-levmar PUBLIC ${LEVMAR_DIR})
+	set_property(TARGET external-levmar PROPERTY FOLDER External)
+	target_link_libraries(external-levmar PRIVATE external-disable-warnings)
+endif()
diff --git a/src/external/lib3ds-1.3.0/CMakeLists.txt b/src/external/lib3ds.cmake
similarity index 74%
rename from src/external/lib3ds-1.3.0/CMakeLists.txt
rename to src/external/lib3ds.cmake
index 3d1fe2c99..b00167a4a 100644
--- a/src/external/lib3ds-1.3.0/CMakeLists.txt
+++ b/src/external/lib3ds.cmake
@@ -1,8 +1,16 @@
-if(TARGET Lib3ds::Lib3ds)
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
+
+option(ALLOW_BUNDLED_LIB3DS "Allow use of bundled lib3ds source" ON)
+option(ALLOW_SYSTEM_LIB3DS "Allow use of system-provided lib3ds" ON)
+
+if(ALLOW_SYSTEM_LIB3DS AND TARGET Lib3ds::Lib3ds)
 	message(STATUS "- lib3ds - using system-provided library")
 	add_library(external-lib3ds INTERFACE)
 	target_link_libraries(external-lib3ds INTERFACE Lib3ds::Lib3ds)
-else()
+elseif(ALLOW_BUNDLED_LIB3DS AND EXISTS "${LIB3DS_DIR}/lib3ds/types.h")
 	message(STATUS "- lib3ds - using bundled source")
 	add_library(
 		external-lib3ds STATIC
@@ -47,5 +55,7 @@ else()
 	target_include_directories(external-lib3ds SYSTEM PUBLIC "${LIB3DS_DIR}")
 	target_compile_definitions(external-lib3ds PUBLIC LIB3DS_STATIC)
 	set_property(TARGET external-lib3ds PROPERTY FOLDER External)
-	target_compile_options(external-lib3ds PRIVATE -w)
+	# TODO not sure what this was for, but it's almost certainly wrong on at least one compiler
+	# since it's not in a compiler conditional.
+	# target_compile_options(external-glew PRIVATE -w)
 endif()
diff --git a/src/external/muparser_v225/CMakeLists.txt b/src/external/muparser.cmake
similarity index 66%
rename from src/external/muparser_v225/CMakeLists.txt
rename to src/external/muparser.cmake
index 7d5abba5a..03df325a2 100644
--- a/src/external/muparser_v225/CMakeLists.txt
+++ b/src/external/muparser.cmake
@@ -1,8 +1,15 @@
-if(TARGET muparser::muparser)
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
+option(ALLOW_BUNDLED_MUPARSER "Allow use of bundled muparser source" ON)
+option(ALLOW_SYSTEM_MUPARSER "Allow use of system-provided muparser" ON)
+
+if(ALLOW_SYSTEM_MUPARSER AND TARGET muparser::muparser)
 	message(STATUS "- muparser - using system-provided library")
 	add_library(external-muparser INTERFACE)
 	target_link_libraries(external-muparser INTERFACE muparser::muparser)
-else()
+elseif(ALLOW_BUNDLED_MUPARSER AND EXISTS "${MUPARSER_DIR}/src/muParser.cpp")
 	message(STATUS "- muparser - using bundled source")
 	add_library(
 		external-muparser STATIC
@@ -18,5 +25,4 @@ else()
 	target_include_directories(external-muparser SYSTEM PUBLIC ${MUPARSER_DIR}/include)
 	target_compile_definitions(external-muparser PUBLIC _UNICODE)
 	set_property(TARGET external-muparser PROPERTY FOLDER External)
-	target_compile_options(external-muparser PRIVATE -w)
 endif()
diff --git a/src/external/newuoa.cmake b/src/external/newuoa.cmake
new file mode 100644
index 000000000..a68e6ffd1
--- /dev/null
+++ b/src/external/newuoa.cmake
@@ -0,0 +1,11 @@
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
+option(ALLOW_BUNDLED_NEWUOA "Allow use of bundled newuoa source" ON)
+
+if(ALLOW_BUNDLED_NEWUOA AND EXISTS "${NEWUOA_DIR}/include/newuoa.h")
+    message(STATUS "- newuoa - using bundled source")
+    add_library(external-newuoa INTERFACE)
+    target_include_directories(external-newuoa INTERFACE ${NEWUOA_DIR}/include)
+endif()
diff --git a/src/external/OpenCTM-1.0.3/CMakeLists.txt b/src/external/openctm.cmake
similarity index 71%
rename from src/external/OpenCTM-1.0.3/CMakeLists.txt
rename to src/external/openctm.cmake
index 6cf6177d5..77f6c6d22 100644
--- a/src/external/OpenCTM-1.0.3/CMakeLists.txt
+++ b/src/external/openctm.cmake
@@ -1,8 +1,15 @@
-if(TARGET OpenCTM::OpenCTM)
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
+option(ALLOW_BUNDLED_OPENCTM "Allow use of bundled OpenCTM source" ON)
+option(ALLOW_SYSTEM_OPENCTM "Allow use of system-provided OpenCTM" ON)
+
+if(ALLOW_SYSTEM_OPENCTM AND TARGET OpenCTM::OpenCTM)
 	message(STATUS "- OpenCTM - using system-provided library")
 	add_library(external-openctm INTERFACE)
 	target_link_libraries(external-openctm INTERFACE OpenCTM::OpenCTM)
-else()
+elseif(ALLOW_BUNDLED_OPENCTM AND EXISTS "${OPENCTM_DIR}/lib/openctm.c")
 	message(STATUS "- OpenCTM - using bundled source")
 	# Modified liblzma included - can't build against system version
 	add_library(
@@ -26,5 +33,4 @@ else()
 		target_compile_definitions(external-openctm PRIVATE _CRT_SECURE_NO_WARNINGS)
 	endif()
 	set_property(TARGET external-openctm PROPERTY FOLDER External)
-	target_compile_options(external-openctm PRIVATE -w)
 endif()
diff --git a/src/external/opengr.cmake b/src/external/opengr.cmake
new file mode 100644
index 000000000..3864b1db8
--- /dev/null
+++ b/src/external/opengr.cmake
@@ -0,0 +1,11 @@
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
+option(ALLOW_BUNDLED_OPENGR "Allow use of bundled OpenGR source" ON)
+
+if(ALLOW_BUNDLED_OPENGR AND EXISTS "${OPENGR_DIR}/src/gr/algorithms/match4pcsBase.h")
+	message(STATUS "- OpenGR - using bundled source")
+	add_library(external-opengr INTERFACE)
+	target_include_directories(external-opengr INTERFACE ${OPENGR_DIR}/src/)
+endif()
diff --git a/src/external/qhull-2003.1/CMakeLists.txt b/src/external/qhull.cmake
similarity index 73%
rename from src/external/qhull-2003.1/CMakeLists.txt
rename to src/external/qhull.cmake
index 733f73532..b3045e499 100644
--- a/src/external/qhull-2003.1/CMakeLists.txt
+++ b/src/external/qhull.cmake
@@ -1,10 +1,17 @@
-if(TARGET Qhull::libqhull)
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
+option(ALLOW_BUNDLED_QHULL "Allow use of bundled Qhull source" ON)
+option(ALLOW_SYSTEM_QHULL "Allow use of system-provided QHull" ON)
+
+if(ALLOW_SYSTEM_QHULL AND TARGET Qhull::libqhull)
 	message(STATUS "- qhull - using system-provided library")
 	add_library(external-qhull INTERFACE)
 	target_link_libraries(external-qhull INTERFACE Qhull::libqhull)
 	target_compile_definitions(external-qhull INTERFACE SYSTEM_QHULL)
 	target_include_directories(external-qhull INTERFACE ${QHULL_libqhull_INCLUDE_DIR}/libqhull)
-else()
+elseif(ALLOW_BUNDLED_QHULL AND EXISTS "${QHULL_DIR}/src/qhull.h")
 	message(STATUS "- qhull - using bundled source")
 	add_library(
 		external-qhull STATIC
@@ -32,5 +39,4 @@ else()
 		"${QHULL_DIR}/src/user.h")
 	target_include_directories(external-qhull INTERFACE "${QHULL_DIR}/src")
 	set_property(TARGET external-qhull PROPERTY FOLDER External)
-	target_compile_options(external-qhull PRIVATE -w)
 endif()
diff --git a/src/external/ssynth.cmake b/src/external/ssynth.cmake
new file mode 100644
index 000000000..2c8f8bb56
--- /dev/null
+++ b/src/external/ssynth.cmake
@@ -0,0 +1,108 @@
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
+option(ALLOW_BUNDLED_SSYNTH "Allow use of bundled structure-synth source" ON)
+
+if(ALLOW_BUNDLED_SSYNTH AND EXISTS "${SSYNTH_DIR}/ssynth/StructureSynth/Model/Action.h")
+	message(STATUS "- structure-synth - using bundled source")
+	# Can't use a system version because using StructureSynth as a library is not common
+	add_library(
+		external-ssynth STATIC
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Action.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/AmbiguousRule.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Builder.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/ColorPool.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/CustomRule.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/ExecutionStack.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/PrimitiveClass.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/PrimitiveRule.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/RandomStreams.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rule.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/RuleRef.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/RuleSet.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/State.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Transformation.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/TransformationLoop.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Parser/EisenParser.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Parser/Preprocessor.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Parser/Tokenizer.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Exceptions/Exception.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Box.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Dot.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/EngineWidget.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Grid.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Line.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Mesh.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Object3D.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/AtomicCounter.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/RayTracer.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/RenderThread.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/Sampler.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/VoxelStepper.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/RaytraceTriangle.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Sphere.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Triangle.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Logging/ListWidgetLogger.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Logging/Logging.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Math/Matrix4.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Math/Random.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Math/Vector3.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/ColorUtils.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/MiniParser.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/Persistence.h"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/Version.h"
+		"${SSYNTH_DIR}/ssynth/ThirdPartyCode/MersenneTwister/MersenneTwister.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rendering/OpenGLRenderer.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rendering/Renderer.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rendering/TemplateRenderer.h"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Action.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/AmbiguousRule.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Builder.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/ColorPool.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/CustomRule.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/ExecutionStack.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/PrimitiveClass.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/PrimitiveRule.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/RandomStreams.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rule.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/RuleRef.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/RuleSet.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/State.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Transformation.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/TransformationLoop.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Parser/EisenParser.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Parser/Preprocessor.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Parser/Tokenizer.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Box.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Dot.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Grid.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Line.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Mesh.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Object3D.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/AtomicCounter.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/RenderThread.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/Sampler.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/VoxelStepper.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/RaytraceTriangle.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Triangle.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Logging/ListWidgetLogger.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Logging/Logging.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Math/Matrix4.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Math/Random.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Math/Vector3.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/ColorUtils.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/MiniParser.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/Persistence.cpp"
+		"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/Version.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rendering/Renderer.cpp"
+		"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rendering/TemplateRenderer.cpp")
+
+	# These sources were disabled in the .pro file: "${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/EngineWidget.cpp"
+	# "${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/RayTracer.cpp"
+	# "${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Sphere.cpp"
+	# "${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rendering/OpenGLRenderer.cpp"
+	target_include_directories(external-ssynth SYSTEM PUBLIC "${SSYNTH_DIR}/ssynth")
+	target_link_libraries(external-ssynth PRIVATE Qt5::Core Qt5::Xml Qt5::OpenGL OpenGL::GLU)
+	set_property(TARGET external-ssynth PROPERTY FOLDER External)
+endif()
diff --git a/src/external/structuresynth-1.5/CMakeLists.txt b/src/external/structuresynth-1.5/CMakeLists.txt
deleted file mode 100644
index f18e6a028..000000000
--- a/src/external/structuresynth-1.5/CMakeLists.txt
+++ /dev/null
@@ -1,101 +0,0 @@
-message(STATUS "- structure-synth - using bundled source")
-# Can't use a system version because using StructureSynth as a library is not common
-add_library(
-	external-ssynth STATIC
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Action.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/AmbiguousRule.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Builder.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/ColorPool.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/CustomRule.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/ExecutionStack.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/PrimitiveClass.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/PrimitiveRule.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/RandomStreams.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rule.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/RuleRef.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/RuleSet.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/State.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Transformation.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/TransformationLoop.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Parser/EisenParser.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Parser/Preprocessor.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Parser/Tokenizer.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Exceptions/Exception.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Box.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Dot.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/EngineWidget.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Grid.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Line.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Mesh.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Object3D.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/AtomicCounter.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/RayTracer.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/RenderThread.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/Sampler.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/VoxelStepper.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/RaytraceTriangle.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Sphere.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Triangle.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Logging/ListWidgetLogger.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Logging/Logging.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Math/Matrix4.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Math/Random.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Math/Vector3.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/ColorUtils.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/MiniParser.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/Persistence.h"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/Version.h"
-	"${SSYNTH_DIR}/ssynth/ThirdPartyCode/MersenneTwister/MersenneTwister.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rendering/OpenGLRenderer.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rendering/Renderer.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rendering/TemplateRenderer.h"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Action.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/AmbiguousRule.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Builder.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/ColorPool.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/CustomRule.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/ExecutionStack.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/PrimitiveClass.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/PrimitiveRule.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/RandomStreams.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rule.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/RuleRef.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/RuleSet.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/State.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Transformation.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/TransformationLoop.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Parser/EisenParser.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Parser/Preprocessor.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Parser/Tokenizer.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Box.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Dot.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Grid.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Line.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Mesh.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Object3D.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/AtomicCounter.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/RenderThread.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/Sampler.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/VoxelStepper.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/RaytraceTriangle.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Triangle.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Logging/ListWidgetLogger.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Logging/Logging.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Math/Matrix4.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Math/Random.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Math/Vector3.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/ColorUtils.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/MiniParser.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/Persistence.cpp"
-	"${SSYNTH_DIR}/ssynth/SyntopiaCore/Misc/Version.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rendering/Renderer.cpp"
-	"${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rendering/TemplateRenderer.cpp")
-
-# These sources were disabled in the .pro file: "${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/EngineWidget.cpp"
-# "${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Raytracer/RayTracer.cpp"
-# "${SSYNTH_DIR}/ssynth/SyntopiaCore/GLEngine/Sphere.cpp"
-# "${SSYNTH_DIR}/ssynth/StructureSynth/Model/Rendering/OpenGLRenderer.cpp"
-target_include_directories(external-ssynth SYSTEM PUBLIC "${SSYNTH_DIR}/ssynth")
-target_link_libraries(external-ssynth PRIVATE Qt5::Core Qt5::Xml Qt5::OpenGL OpenGL::GLU)
-set_property(TARGET external-ssynth PROPERTY FOLDER External)
-target_compile_options(external-ssynth PRIVATE -w)
diff --git a/src/external/u3d.cmake b/src/external/u3d.cmake
new file mode 100644
index 000000000..12b36294b
--- /dev/null
+++ b/src/external/u3d.cmake
@@ -0,0 +1,10 @@
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
+option(ALLOW_BUNDLED_U3D "Allow use of bundled u3d source" ON)
+
+if(ALLOW_BUNDLED_U3D AND EXISTS "${U3D_DIR}/CMakeLists.txt")
+	message(STATUS "- u3d - using bundled source")
+	add_subdirectory(${U3D_DIR})
+endif()
diff --git a/src/external/u3d/CMakeLists.txt b/src/external/u3d/CMakeLists.txt
index 7182dd214..be0197c47 100644
--- a/src/external/u3d/CMakeLists.txt
+++ b/src/external/u3d/CMakeLists.txt
@@ -1,4 +1,3 @@
-message(STATUS "- u3d - using bundled source")
 
 IF(APPLE)
 # Tiger build
diff --git a/src/external_common.cmake b/src/external_common.cmake
index 70ffc22de..346f3ff3b 100644
--- a/src/external_common.cmake
+++ b/src/external_common.cmake
@@ -1,17 +1,20 @@
+# Copyright 2019, 2020, Collabora, Ltd.
+# Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
+# SPDX-License-Identifier: BSL-1.0
+
 # GLEW - required
 set(GLEW_DIR ${EXTERNAL_DIR}/glew-2.1.0)
-add_subdirectory(${GLEW_DIR})
+include(${EXTERNAL_DIR}/glew.cmake)
 
 
-# VCGLIb -- required
+# VCGLib -- required
 if(NOT VCGDIR)
 	get_filename_component(VCGDIR "${CMAKE_CURRENT_LIST_DIR}/vcglib" ABSOLUTE)
 	if(NOT EXISTS ${VCGDIR})
 		set(VCGDIR NOTFOUND)
 	endif()
 endif()
-set(VCGDIR
-	"${VCGDIR}")
+set(VCGDIR "${VCGDIR}")
 
 if(NOT VCGDIR)
 	message(FATAL_ERROR "VCGLib not found. Please clone recursively the MeshLab repo.")
@@ -21,11 +24,5 @@ include_directories(${VCGDIR} ${CMAKE_CURRENT_SOURCE_DIR})
 
 # Eigen3 - required
 set(EIGEN_DIR ${VCGDIR}/eigenlib)
-if(EIGEN3_INCLUDE_DIR)
-	message(STATUS "- Eigen - using system-provided library")
-	set(EIGEN_INCLUDE_DIRS ${EIGEN3_INCLUDE_DIR})
-else()
-	message(STATUS "- Eigen - using bundled source")
-	set(EIGEN_INCLUDE_DIRS ${EIGEN_DIR})
-endif()
+include(${EXTERNAL_DIR}/eigen.cmake)
 include_directories(${EIGEN_INCLUDE_DIRS})