Building Polyscope as a shared library on Windows

[P4T0U]

On Windows, I managed to build polyscope as a shared library with a couple of changes:

1. Export all symbols for polyscope

--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -374,4 +374,7 @@
 set_target_properties(polyscope PROPERTIES POSITION_INDEPENDENT_CODE TRUE)
 add_definitions(-DNOMINMAX)
+set_target_properties(polyscope PROPERTIES
+  WINDOWS_EXPORT_ALL_SYMBOLS ON
+)
 
 # Include settings

2. Force imgui as static. Again, it would search for a .lib file but no symbols are exported.

--- a/deps/imgui/CMakeLists.txt
+++ b/deps/imgui/CMakeLists.txt
@@ -63,5 +63,5 @@
 
   add_library(
-          imgui
+          imgui STATIC
           ${SRCS}
           )

Alternative: Export all symbols like 1.

3. Force stb as static. Otherwise, it would search for a non-existent .lib file because no symbols are exported.

--- a/deps/stb/CMakeLists.txt
+++ b/deps/stb/CMakeLists.txt
@@ -1,5 +1,5 @@
 # Create a library for the viewer code
 add_library(
-    stb
+    stb STATIC
     stb_impl.cpp
 )

I tried exporting all symbols but it did not work. I would get missing symbols:

[build] screenshot.cpp.obj : error LNK2001: unresolved external symbol "int stbi_write_png_compression_level" (?stbi_write_png_compression_level@@3HA)

4. Tell glm to not build a library. It is header-only anyway:

set(GLM_BUILD_LIBRARY OFF CACHE BOOL "Use GLM as header-only" FORCE)

It is not optimal to export all symbols on Windows, but it works. Dropping this here for others to use.

Open to make a PR but I would rather figure out the approved method first 😄

[T7imal]

https://cmake.org/cmake/help/latest/prop_tgt/WINDOWS_EXPORT_ALL_SYMBOLS.html
For global data symbols, __declspec(dllimport) must still be used when compiling against the code in the .dll.

So you still need to explicitly export global variables.

[P4T0U]

https://cmake.org/cmake/help/latest/prop_tgt/WINDOWS_EXPORT_ALL_SYMBOLS.html
For global data symbols, __declspec(dllimport) must still be used when compiling against the code in the .dll.

So you still need to explicitly export global variables.

Thank you! You are right. Because of that, I wasn't able to specify a user Callback. I had to create a export.h:

#ifndef POLYSCOPE_EXPORT_H
#define POLYSCOPE_EXPORT_H

#ifdef _WIN32
  #ifdef POLYSCOPE_DLL_EXPORTS
    #define POLYSCOPE_API __declspec(dllexport)
  #else
    #define POLYSCOPE_API __declspec(dllimport)
  #endif
#else
  #define POLYSCOPE_API
#endif

#endif // POLYSCOPE_EXPORT_H

and in polyscope.h, add it to the declaration like follows:

POLYSCOPE_API extern std::function<void()>& userCallback;

then finally, add POLYSCOPE_DLL_EXPORTS to the definition:

target_compile_definitions(polyscope PRIVATE POLYSCOPE_DLL_EXPORTS)

I'm still a beginner with Polyscope so I'm not sure what other variables need exporting.