remove nexus submodule and download it using cmake

.gitmodules

@@ -2,6 +2,3 @@
 	path = src/vcglib
 	url = https://github.com/cnr-isti-vclab/vcglib
 	branch = devel
-[submodule "src/external/nexus"]
-	path = src/external/nexus
-	url = https://github.com/cnr-isti-vclab/nexus

src/external/newuoa.cmake

@@ -2,11 +2,11 @@
 # 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)
+option(MESHLAB_ALLOW_BUNDLED_NEWUOA "Allow use of bundled newuoa source" ON)
 
 set(NEWUOA_DIR ${VCGDIR}/wrap/newuoa)
 
-if(ALLOW_BUNDLED_NEWUOA AND EXISTS "${NEWUOA_DIR}/include/newuoa.h")
+if(MESHLAB_ALLOW_BUNDLED_NEWUOA AND EXISTS "${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)

src/external/nexus.cmake

@@ -2,12 +2,31 @@
 # Copyright 2019, 2020, Visual Computing Lab, ISTI - Italian National Research Council
 # SPDX-License-Identifier: BSL-1.0
 
-option(ALLOW_BUNDLED_NEXUS "Allow use of bundled nexus source" ON)
+option(MESHLAB_ALLOW_DOWNLOAD_SOURCE_NEXUS "Allow download and use of nexus source" ON)
+
+if(MESHLAB_ALLOW_DOWNLOAD_SOURCE_NEXUS)
+	# todo - make release of nexus and corto
+	set(NEXUS_DIR ${MESHLAB_EXTERNAL_DOWNLOAD_DIR}/nexus-master)
+	set(CORTO_DIR ${NEXUS_DIR}/src/corto)
+
+	if (NOT EXISTS "${NEXUS_DIR}/CMakeLists.txt")
+		set(NEXUS_LINK https://github.com/cnr-isti-vclab/nexus/archive/refs/heads/master.zip)
+		download_and_unzip(${NEXUS_LINK} ${MESHLAB_EXTERNAL_DOWNLOAD_DIR} "nexus")
+	endif()
+
+	if (NOT EXISTS "${CORTO_DIR}/CMakeLists.txt")
+		set(CORTO_LINK https://github.com/cnr-isti-vclab/corto/archive/refs/heads/master.zip)
+		download_and_unzip(${CORTO_LINK} "${NEXUS_DIR}/src/" "corto")
+		file(REMOVE ${NEXUS_DIR}/src/corto)
+		file(RENAME ${NEXUS_DIR}/src/corto-master ${NEXUS_DIR}/src/corto)
+	endif()
+
+	message(STATUS "- nexus - using downloaded source")
 
-if(ALLOW_BUNDLED_NEXUS AND EXISTS "${CMAKE_CURRENT_LIST_DIR}/nexus/CMakeLists.txt")
-	message(STATUS "- nexus - using bundled source")
 	set (BUILD_NXS_BUILD OFF)
 	set (BUILD_NXS_EDIT OFF)
 	set (BUILD_NXS_VIEW OFF)
-	add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/nexus EXCLUDE_FROM_ALL)
+	add_subdirectory(${NEXUS_DIR} EXCLUDE_FROM_ALL)
+	add_library(external-nexus INTERFACE)
+	target_link_libraries(external-nexus INTERFACE nexus)
 endif()

src/meshlabplugins/filter_io_nxs/CMakeLists.txt

@@ -2,15 +2,15 @@
 # SPDX-License-Identifier: BSL-1.0
 
 # Only build if we have nexus
-if (TARGET nexus)
+if (TARGET external-nexus)
 
 	set(SOURCES filter_io_nxs.cpp)
 
 	set(HEADERS filter_io_nxs.h)
 
 	add_meshlab_plugin(filter_io_nxs MODULE ${SOURCES} ${HEADERS})
 
-	target_link_libraries(filter_io_nxs PRIVATE nexus)
+	target_link_libraries(filter_io_nxs PRIVATE external-nexus)
 
 else()
 	message(STATUS "Skipping filter_io_nxs - missing nexus")