vcpkg/ports/libigl/fix-dependency.patch

diff --git a/cmake/libigl.cmake b/cmake/libigl.cmake
index 7016cbf..3a6b4dd 100644
--- a/cmake/libigl.cmake
+++ b/cmake/libigl.cmake
@@ -96,8 +96,9 @@ if(UNIX)
 endif()
 
 # Eigen
-if(TARGET Eigen3::Eigen)
+if(1)
   # If an imported target already exists, use it
+  find_package(Eigen3 CONFIG REQUIRED)
   target_link_libraries(igl_common INTERFACE Eigen3::Eigen)
 else()
   igl_download_eigen()
@@ -182,7 +183,7 @@ compile_igl_module("core" ${SOURCES_IGL})
 ################################################################################
 ### Download the python part ###
 if(LIBIGL_WITH_PYTHON)
-  igl_download_pybind11()
+  #igl_download_pybind11()
 endif()
 
 ################################################################################
@@ -281,7 +282,8 @@ if(LIBIGL_WITH_EMBREE)
     set(EMBREE_STATIC_RUNTIME ON CACHE BOOL " " FORCE)
   endif()
 
-  if(NOT TARGET embree)
+  find_package(embree 3 CONFIG REQUIRED)
+  if(0)
     # TODO: Should probably save/restore the CMAKE_CXX_FLAGS_*, since embree seems to be
     # overriding them on Windows. But well... it works for now.
     igl_download_embree()
@@ -289,7 +291,7 @@ if(LIBIGL_WITH_EMBREE)
   endif()
 
   compile_igl_module("embree")
-  target_link_libraries(igl_embree ${IGL_SCOPE} embree)
+  target_link_libraries(igl_embree ${IGL_SCOPE} sys math simd embree)
   target_include_directories(igl_embree ${IGL_SCOPE} ${EMBREE_DIR}/include)
   target_compile_definitions(igl_embree ${IGL_SCOPE} -DEMBREE_STATIC_LIB)
 endif()
@@ -332,11 +334,12 @@ if(LIBIGL_WITH_OPENGL)
   endif()
 
   # glad module
-  if(NOT TARGET glad)
+  find_package(glad CONFIG REQUIRED)
+  if(0)
     igl_download_glad()
     add_subdirectory(${LIBIGL_EXTERNAL}/glad glad)
   endif()
-  target_link_libraries(igl_opengl ${IGL_SCOPE} glad)
+  target_link_libraries(igl_opengl ${IGL_SCOPE} glad::glad)
 endif()
 
 ################################################################################
@@ -345,7 +348,8 @@ if(LIBIGL_WITH_OPENGL_GLFW)
   if(TARGET igl::opengl)
     # GLFW module
     compile_igl_module("opengl/glfw")
-    if(NOT TARGET glfw)
+    find_package(glfw3 CONFIG REQUIRED)
+    if(0)
       set(GLFW_BUILD_EXAMPLES OFF CACHE BOOL " " FORCE)
       set(GLFW_BUILD_TESTS OFF CACHE BOOL " " FORCE)
       set(GLFW_BUILD_DOCS OFF CACHE BOOL " " FORCE)
@@ -363,9 +367,10 @@ if(LIBIGL_WITH_OPENGL_GLFW_IMGUI)
   if(TARGET igl::opengl_glfw)
     # ImGui module
     compile_igl_module("opengl/glfw/imgui")
-    if(NOT TARGET imgui)
+    find_package(imgui CONFIG REQUIRED)
+    if(0)
       igl_download_imgui()
-      add_subdirectory(${LIBIGL_EXTERNAL}/libigl-imgui imgui)
+      add_subdirectory(${LIBIGL_EXTERNAL}/libigl-imgui imgui::imgui)
     endif()
     target_link_libraries(igl_opengl_glfw_imgui ${IGL_SCOPE} igl_opengl_glfw imgui)
   endif()
@@ -377,12 +382,21 @@ if(LIBIGL_WITH_PNG)
   # png/ module is anomalous because it also depends on opengl it really should
   # be moved into the opengl/ directory and namespace ...
   if(TARGET igl_opengl)
-    if(NOT TARGET stb_image)
+    find_path(stb_include_dir stb.h)
+    find_package(opengl REQUIRED)
+    find_package(libpng CONFIG REQUIRED)
+    if (BUILD_SHARED_LIBS)
+        set(libpng_LIBRARIES png)
+    else()
+        set(libpng_LIBRARIES png_static)
+    endif()
+    if(0)
       igl_download_stb()
       add_subdirectory(${LIBIGL_EXTERNAL}/stb stb_image)
     endif()
     compile_igl_module("png" "")
-    target_link_libraries(igl_png ${IGL_SCOPE} igl_stb_image igl_opengl)
+    target_include_directories(igl_png PUBLIC ${stb_include_dir})
+    target_link_libraries(igl_png ${IGL_SCOPE} OpenGL::GL ${libpng_LIBRARIES})
   endif()
 endif()
 
@@ -430,7 +444,8 @@ endif()
 ### Compile the xml part ###
 if(LIBIGL_WITH_XML)
   set(TINYXML2_DIR "${LIBIGL_EXTERNAL}/tinyxml2")
-  if(NOT TARGET tinyxml2)
+  find_package(tinyxml2 CONFIG REQUIRED)
+  if(0)
     igl_download_tinyxml2()
     add_library(tinyxml2 STATIC ${TINYXML2_DIR}/tinyxml2.cpp ${TINYXML2_DIR}/tinyxml2.h)
     target_include_directories(tinyxml2 PUBLIC ${TINYXML2_DIR})
@@ -440,7 +455,7 @@ if(LIBIGL_WITH_XML)
             SOVERSION "3")
   endif()
   compile_igl_module("xml")
-  target_link_libraries(igl_xml ${IGL_SCOPE} tinyxml2)
+  target_link_libraries(igl_xml ${IGL_SCOPE} tinyxml2::tinyxml2)
   target_include_directories(igl_xml ${IGL_SCOPE} ${TINYXML2_DIR})
 endif()
 
diff --git a/include/igl/opengl/glfw/imgui/ImGuiHelpers.h b/include/igl/opengl/glfw/imgui/ImGuiHelpers.h
index 1d3e3bc..682b6d7 100644
--- a/include/igl/opengl/glfw/imgui/ImGuiHelpers.h
+++ b/include/igl/opengl/glfw/imgui/ImGuiHelpers.h
@@ -10,7 +10,7 @@
 
 ////////////////////////////////////////////////////////////////////////////////
 #include "ImGuiTraits.h"
-#include <imgui/imgui.h>
+#include <imgui.h>
 #include <vector>
 #include <string>
 #include <algorithm>
diff --git a/include/igl/opengl/glfw/imgui/ImGuiMenu.cpp b/include/igl/opengl/glfw/imgui/ImGuiMenu.cpp
index 3939b03..835b208 100644
--- a/include/igl/opengl/glfw/imgui/ImGuiMenu.cpp
+++ b/include/igl/opengl/glfw/imgui/ImGuiMenu.cpp
@@ -9,7 +9,7 @@
 #include "ImGuiMenu.h"
 #include "ImGuiHelpers.h"
 #include <igl/project.h>
-#include <imgui/imgui.h>
+#include <imgui.h>
 #include <imgui_impl_glfw.h>
 #include <imgui_impl_opengl3.h>
 #include <imgui_fonts_droid_sans.h>
diff --git a/include/igl/opengl/glfw/imgui/ImGuiTraits.h b/include/igl/opengl/glfw/imgui/ImGuiTraits.h
index fbc892f..e8828b1 100644
--- a/include/igl/opengl/glfw/imgui/ImGuiTraits.h
+++ b/include/igl/opengl/glfw/imgui/ImGuiTraits.h
@@ -8,7 +8,7 @@
 #ifndef IGL_OPENGL_GLFW_IMGUI_IMGUITRAITS_H
 #define IGL_OPENGL_GLFW_IMGUI_IMGUITRAITS_H
 
-#include <imgui/imgui.h>
+#include <imgui.h>
 
 // Extend ImGui by populating its namespace directly
 namespace ImGui
diff --git a/python/CMakeLists.txt b/python/CMakeLists.txt
index 7a14775..f5c84a8 100644
--- a/python/CMakeLists.txt
+++ b/python/CMakeLists.txt
@@ -23,8 +23,8 @@ endif()
 # set(PYTHON_INCLUDE_DIR "/usr/local/Cellar/python3/3.5.0/Frameworks/Python.framework/Versions/3.5/include/python3.5m")
 
 set(Python_ADDITIONAL_VERSIONS 3.4 3.5 3.6 3.7)
-find_package(PythonInterp 3.4 REQUIRED)
-find_package(PythonLibs 3.4 REQUIRED)
+find_package(PythonInterp REQUIRED)
+find_package(PythonLibs REQUIRED)
 
 ## libigl
 if(NOT TARGET igl::core)
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 8a0af13..5c6a350 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -11,16 +11,14 @@ else()
 endif()
 
 ### Download data
-igl_download_test_data()
 set(IGL_TEST_DATA ${LIBIGL_EXTERNAL}/../tests/data)
 
 ### Download Catch2 unit test framework
-igl_download_catch2()
+find_package(Catch2 CONFIG REQUIRED)
 list(APPEND CMAKE_MODULE_PATH ${LIBIGL_EXTERNAL}/catch2/contrib)
 
 
 # Add catch2
-add_subdirectory(${LIBIGL_EXTERNAL}/catch2 catch2)
 
 
 # Create test executable
diff --git a/tutorial/106_ViewerMenu/main.cpp b/tutorial/106_ViewerMenu/main.cpp
index 09f3272..9e1a19d 100644
--- a/tutorial/106_ViewerMenu/main.cpp
+++ b/tutorial/106_ViewerMenu/main.cpp
@@ -2,7 +2,7 @@
 #include <igl/opengl/glfw/Viewer.h>
 #include <igl/opengl/glfw/imgui/ImGuiMenu.h>
 #include <igl/opengl/glfw/imgui/ImGuiHelpers.h>
-#include <imgui/imgui.h>
+#include <imgui.h>
 #include <iostream>
 #include "tutorial_shared_path.h"