Add conditional support for linking draco library

Can be opted out by setting WITH_DRACO cmake option to false

CMakeLists.txt

@@ -293,6 +293,8 @@ if(WITH_CORE)
 
   set (WITH_COPC TRUE CACHE BOOL "Determines whether Cloud Optimized Point Cloud (COPC) support should be built")
 
+  set (WITH_DRACO TRUE CACHE BOOL "Determines whether Draco support should be built")
+
   set (WITH_THREAD_LOCAL TRUE CACHE BOOL "Determines whether std::thread_local should be used")
   mark_as_advanced(WITH_THREAD_LOCAL)
 
@@ -443,6 +445,12 @@ if(WITH_CORE)
     endif()
   endif()
 
+  if (WITH_DRACO)
+    find_package(Draco REQUIRED)
+    message(STATUS "Found Draco: ${DRACO_LIBRARY} (${DRACO_VERSION})")
+    set(HAVE_DRACO TRUE)  # used in qgisconfig.h
+  endif()
+
   #############################################################
   # search for Qt
 

cmake/FindDraco.cmake

@@ -0,0 +1,92 @@
+# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+# file Copyright.txt or https://cmake.org/licensing for details.
+# based on https://github.com/hlrs-vis/covise/blob/b909e6fad418e23e48726ab44de1bb36e82a24f8/cmake/FindDRACO.cmake#L4
+
+# - Find DRACO
+# Find the DRACO includes and library
+#
+#  DRACO_INCLUDE_DIR - Where to find DRACO includes
+#  DRACO_FOUND       - True if DRACO was found
+
+IF(DRACO_INCLUDE_DIR)
+  SET(DRACO_FIND_QUIETLY TRUE)
+ENDIF(DRACO_INCLUDE_DIR)
+
+FIND_PATH(DRACO_INCLUDE_DIR "draco/draco_features.h"
+  PATHS
+  $ENV{DRACO_HOME}/include
+  $ENV{EXTERNLIBS}/DRACO/include
+  ~/Library/Frameworks
+  /Library/Frameworks
+  /usr/local
+  /usr
+  /sw # Fink
+  /opt/local # DarwinPorts
+  /opt/csw # Blastwave
+  /opt
+  DOC "DRACO - Headers"
+)
+
+SET(DRACO_NAMES draco)
+SET(DRACO_DBG_NAMES dracod)
+
+FIND_LIBRARY(DRACO_LIBRARY NAMES ${DRACO_NAMES}
+  PATHS
+  $ENV{DRACO_HOME}
+  $ENV{EXTERNLIBS}/DRACO
+  ~/Library/Frameworks
+  /Library/Frameworks
+  /usr/local
+  /usr
+  /sw
+  /opt/local
+  /opt/csw
+  /opt
+  PATH_SUFFIXES lib lib64
+  DOC "DRACO - Library"
+)
+
+INCLUDE(FindPackageHandleStandardArgs)
+
+IF(MSVC)
+  # VisualStudio needs a debug version
+  FIND_LIBRARY(DRACO_LIBRARY_DEBUG NAMES ${DRACO_DBG_NAMES}
+    PATHS
+    $ENV{DRACO_HOME}
+    $ENV{EXTERNLIBS}/DRACO
+    PATH_SUFFIXES lib lib64
+    DOC "DRACO - Library (Debug)"
+  )
+
+  IF(DRACO_LIBRARY_DEBUG AND DRACO_LIBRARY)
+    SET(DRACO_LIBRARIES optimized ${DRACO_LIBRARY} debug ${DRACO_LIBRARY_DEBUG})
+  ENDIF(DRACO_LIBRARY_DEBUG AND DRACO_LIBRARY)
+
+  FIND_PACKAGE_HANDLE_STANDARD_ARGS(DRACO DEFAULT_MSG DRACO_LIBRARY DRACO_LIBRARY_DEBUG DRACO_INCLUDE_DIR)
+
+  MARK_AS_ADVANCED(DRACO_LIBRARY DRACO_LIBRARY_DEBUG DRACO_INCLUDE_DIR)
+
+ELSE(MSVC)
+  # rest of the world
+  SET(DRACO_LIBRARIES ${DRACO_LIBRARY})
+
+  FIND_PACKAGE_HANDLE_STANDARD_ARGS(Draco DEFAULT_MSG DRACO_LIBRARY DRACO_INCLUDE_DIR)
+
+  MARK_AS_ADVANCED(DRACO_LIBRARY DRACO_INCLUDE_DIR)
+
+ENDIF(MSVC)
+
+IF(DRACO_FOUND)
+  SET(DRACO_INCLUDE_DIRS ${DRACO_INCLUDE_DIR})
+
+  set(draco_version_file
+        "${DRACO_INCLUDE_DIR}/draco/core/draco_version.h")
+    file(STRINGS "${draco_version_file}" draco_version REGEX "kDracoVersion")
+    list(GET draco_version 0 draco_version)
+    string(REPLACE "static const char kDracoVersion[] = " "" draco_version
+                   "${draco_version}")
+    string(REPLACE ";" "" draco_version "${draco_version}")
+    string(REPLACE "\"" "" draco_version "${draco_version}")
+    set(DRACO_VERSION ${draco_version})
+
+ENDIF(DRACO_FOUND)

cmake_templates/qgsconfig.h.in

@@ -112,6 +112,8 @@
 #define PDAL_VERSION_MINOR "${PDAL_VERSION_MINOR}"
 #define PDAL_VERSION_MICRO "${PDAL_VERSION_MICRO}"
 
+#cmakedefine HAVE_DRACO
+
 #cmakedefine ENABLE_TESTS
 
 #cmakedefine HAS_KDE_QT5_PDF_TRANSFORM_FIX

src/core/CMakeLists.txt

@@ -2314,6 +2314,7 @@ target_include_directories(qgis_core PUBLIC
   ${CMAKE_SOURCE_DIR}/external/nmea
   ${CMAKE_SOURCE_DIR}/external/rtree/include
   ${CMAKE_SOURCE_DIR}/external/meshOptimizer
+  ${CMAKE_SOURCE_DIR}/external/tinygltf
 )
 
 if (WITH_EPT)
@@ -2418,6 +2419,11 @@ target_link_libraries(qgis_core
   ${ZLIB_LIBRARIES}
   ${EXIV2_LIBRARY}
 )
+
+if (WITH_DRACO)
+  target_link_libraries(qgis_core ${DRACO_LIBRARY})
+endif()
+
 if (NOT IOS)
   target_link_libraries(qgis_core ${QT_VERSION_BASE}::PrintSupport)
 endif()