attempt to fix glew issue

Former-commit-id: 421c9bc95947bd18cc18cfbcc0a6e7a20a828abd

shared/cmake/CMakeLists.txt

@@ -319,8 +319,8 @@ if(LIBIGL_WITH_OPENGL)
     CompileIGL_Module("opengl" "")
     CompileIGL_Module("opengl2" "")
     if(NOT APPLE)
-      target_include_directories(igl_opengl PRIVATE "${LIBIGL_EXTERNAL}/nanogui/ext/glew/include")
-      target_include_directories(igl_opengl2 PRIVATE "${LIBIGL_EXTERNAL}/nanogui/ext/glew/include")
+      target_include_directories(igl_opengl PRIVATE "${NANOGUI_DIR}/ext/glew/include")
+      target_include_directories(igl_opengl2 PRIVATE "${NANOGUI_DIR}/ext/glew/include")
     endif()
   endif()
   set(LIBIGL_OPENGL_EXTRA_LIBRARIES ${OPENGL_gl_LIBRARY})
@@ -346,7 +346,7 @@ if(LIBIGL_WITH_OPENGL)
       target_include_directories(igl_opengl_glfw PRIVATE ${GLFW_INCLUDE_DIRS})
       target_include_directories(igl_opengl_glfw PRIVATE ${OPENGL_INCLUDE_DIR})
       if(NOT APPLE)
-        target_include_directories(igl_opengl PRIVATE "${LIBIGL_EXTERNAL}/nanogui/ext/glew/include")
+        target_include_directories(igl_opengl PRIVATE "${NANOGUI_DIR}/ext/glew/include")
       endif()
     endif()
     list(APPEND LIBIGL_INCLUDE_DIRS ${GLFW_INCLUDE_DIRS})
@@ -380,6 +380,9 @@ if(LIBIGL_WITH_OPENGL)
           target_compile_definitions(igl_viewer PRIVATE -DIGL_VIEWER_WITH_NANOGUI)
         endif()
         target_include_directories(igl_viewer PRIVATE ${VIEWER_INCLUDE_DIRS})
+        if(NOT APPLE)
+          target_include_directories(igl_viewer PRIVATE "${NANOGUI_DIR}/ext/glew/include")
+        endif()
       endif()
     endif()
   endif()
@@ -400,7 +403,7 @@ if(LIBIGL_WITH_PNG)
     CompileIGL_Module("png" "")
     target_include_directories(igl_png PRIVATE ${STB_IMAGE_DIR})
     if(NOT APPLE)
-      target_include_directories(igl_png PRIVATE "${LIBIGL_EXTERNAL}/nanogui/ext/glew/include")
+      target_include_directories(igl_png PRIVATE "${NANOGUI_DIR}/ext/glew/include")
     endif()
   endif()
 endif()