Fix GLUT dependency check for Windows (#1405)

* Test if find_package(GLUT) works on Windows

* Set DART_VERBOSE=On on Appveyor

* Print warning for disabled component due to missing dependent target

* Install tinyxml2 on Appveyor

* Install opengl and freeglut to see if dart-gui is built

* Update glut package name

.appveyor.yml

@@ -52,7 +52,8 @@ install:
   - cmd: vcpkg install --recurse --triplet %VCPKG_ARCH% assimp boost-system boost-filesystem ccd eigen3 fcl
 
   # install optional dependencies
-  #- vcpkg install --recurse --triplet %VCPKG_ARCH% bullet3 flann freeglut nlopt ode opengl osg tinyxml2 urdfdom
+  - cmd: vcpkg install --recurse --triplet %VCPKG_ARCH% freeglut opengl tinyxml2
+  #- vcpkg install --recurse --triplet %VCPKG_ARCH% bullet3 flann nlopt ode osg urdfdom
   #- vcpkg install ipopt:%VCPKG_ARCH%
 
   - cmd: vcpkg integrate install

cmake/DARTMacros.cmake

@@ -146,6 +146,16 @@ macro(dart_check_optional_package variable component dependency)
   endif()
 endmacro()
 
+#===============================================================================
+macro(dart_check_dependent_target target)
+  foreach(dependent_target ${ARGN})
+    if (NOT TARGET ${dependent_target})
+      message(WARNING "${target} is disabled because dependent target ${dependent_target} is not being built.")
+      return()
+    endif()
+  endforeach()
+endmacro()
+
 #===============================================================================
 function(dart_add_custom_target rel_dir property_name)
   set(abs_dir "${CMAKE_CURRENT_LIST_DIR}/${rel_dir}")

dart/gui/CMakeLists.txt

@@ -1,23 +1,23 @@
+# Set local target name
+set(target_name ${PROJECT_NAME}-gui)
+set(component_name gui)
+
 # Dependency checks
-if (NOT TARGET dart-utils)
-  return()
-endif()
+dart_check_dependent_target(${target_name} dart-utils)
 
 dart_find_package(OpenGL)
 dart_check_optional_package(OPENGL "dart-gui" "OpenGL")
 
+dart_find_package(GLUT)
 if(WIN32 AND NOT CYGWIN)
-  set(GLUT_INCLUDE_DIR "${CMAKE_INSTALL_PREFIX}/include")
-  set(GLUT_LIBRARIES glut32)
-  set(HAVE_GLUT TRUE)
+  dart_check_optional_package(GLUT "dart-gui" "freeglut")
 else()
-  dart_find_package(GLUT)
   dart_check_optional_package(GLUT "dart-gui" "freeglut3")
-  if(GLUT_FOUND)
-    set(HAVE_GLUT TRUE)
-  else()
-    set(HAVE_GLUT FALSE)
-  endif()
+endif()
+if(GLUT_FOUND)
+  set(HAVE_GLUT TRUE)
+else()
+  set(HAVE_GLUT FALSE)
 endif()
 
 # Search all header and source files
@@ -38,10 +38,6 @@ add_subdirectory(glut)
 get_property(dart_gui_headers GLOBAL PROPERTY DART_GUI_HEADERS)
 get_property(dart_gui_sources GLOBAL PROPERTY DART_GUI_SOURCES)
 
-# Set local target name
-set(target_name ${PROJECT_NAME}-gui)
-set(component_name gui)
-
 # Add target
 dart_add_library(${target_name}
   ${hdrs} ${srcs} ${dart_gui_headers} ${dart_gui_sources}

dart/gui/osg/CMakeLists.txt

@@ -1,7 +1,9 @@
+# Set local target name
+set(target_name ${PROJECT_NAME}-gui-osg)
+set(component_name gui-osg)
+
 # Dependency checks
-if (NOT TARGET dart-gui)
-  return()
-endif()
+dart_check_dependent_target(${target_name} dart-gui)
 
 # OpenSceneGraph
 if(DART_BUILD_GUI_OSG)
@@ -62,10 +64,6 @@ set(dart_gui_osg_srcs ${srcs})
 
 add_subdirectory(render)
 
-# Set local target name
-set(target_name ${PROJECT_NAME}-gui-osg)
-set(component_name gui-osg)
-
 # Add target
 dart_add_library(${target_name} ${hdrs} ${srcs} ${dart_gui_osg_hdrs} ${dart_gui_osg_srcs})
 target_include_directories(