utf8 header not found

code/CMakeLists.txt

@@ -923,7 +923,7 @@ IF(ASSIMP_HUNTER_ENABLED)
   hunter_add_package(utf8)
   find_package(utf8cpp CONFIG REQUIRED)
 ELSE()
-  # utf8 is header-only, so Assimp doesn't need to do anything.
+  INCLUDE_DIRECTORIES("../contrib/utf8cpp/source")
 ENDIF()
 
 # polyclipping

samples/SimpleTexturedDirectx11/CMakeLists.txt

@@ -19,6 +19,7 @@ INCLUDE_DIRECTORIES(
   ${Assimp_SOURCE_DIR}/include
   ${Assimp_SOURCE_DIR}/code
   ${SAMPLES_SHARED_CODE_DIR}
+  ${Assimp_SOURCE_DIR}/contrib/utf8cpp/source
 )
 
 LINK_DIRECTORIES(

samples/SimpleTexturedDirectx11/SimpleTexturedDirectx11/main.cpp

@@ -23,6 +23,7 @@
 #include <dxgi1_2.h>
 #include <DirectXMath.h>
 #include <d3dcompiler.h>
+#include <utf8.h>
 
 #include "ModelLoader.h"
 #include "SafeRelease.hpp"

samples/SimpleTexturedOpenGL/CMakeLists.txt

@@ -21,6 +21,7 @@ INCLUDE_DIRECTORIES(
   ${OPENGL_INCLUDE_DIR}
   ${GLUT_INCLUDE_DIR}
   ${SAMPLES_SHARED_CODE_DIR}
+  ${Assimp_SOURCE_DIR}/contrib/utf8cpp/source
 )
 
 LINK_DIRECTORIES(

samples/SimpleTexturedOpenGL/SimpleTexturedOpenGL/src/model_loading.cpp

@@ -17,6 +17,7 @@
 #include <stdio.h>
 #include <GL/gl.h>
 #include <GL/glu.h>
+#include <utf8.h>
 
 #ifdef _MSC_VER
 #pragma warning(disable: 4100) // Disable warning 'unreferenced formal parameter'