Migrate OVRMobile plugin to godot-cpp

[m4gr3d]

This PR migrates the Oculus mobile plugin to godot-cpp.

At the expense of binary size increase, this enables to leverage the rich apis providing by the godot-cpp library to improve the plugin functionality.

[m4gr3d]

@NeoSpark314 @BastiaanOlij I'd appreciate your feedback on this change to the plugin. Thanks!

[NeoSpark314]

I just tried to build it; I did a git submodule update --init --recursive to get the godot headers but when I build I get the following error:

  In file included from ../../../../src/main/cpp\ovr_mobile_session.h:9:

  In file included from ../../../../src/main/cpp/framebuffer.h:15:

  In file included from ../../../../src/main/cpp/common.h:48:

  In file included from ../../../../libs/godot-cpp/include\core/Godot.hpp:12:

  ../../../../libs/godot-cpp/include/core/Ref.hpp:5:10: fatal error: 'Reference.hpp' file not found

  #include "Reference.hpp"

Do you have an idea what I might be missing?

[m4gr3d]

I just tried to build it; I did a git submodule update --init --recursive to get the godot headers but when I build I get the following error:

  In file included from ../../../../src/main/cpp\ovr_mobile_session.h:9:

  In file included from ../../../../src/main/cpp/framebuffer.h:15:

  In file included from ../../../../src/main/cpp/common.h:48:

  In file included from ../../../../libs/godot-cpp/include\core/Godot.hpp:12:

  ../../../../libs/godot-cpp/include/core/Ref.hpp:5:10: fatal error: 'Reference.hpp' file not found

  #include "Reference.hpp"

Do you have an idea what I might be missing?

@NeoSpark314 Sorry, I missed a step. Once you run the git submodule command, you must generate the godot-cpp bindings by following these steps.

I'll update the readme accordingly.

[NeoSpark314]

Thanks @m4gr3d; I build the libgodot-cpp files now (both libgodot-cpp.android.debug.arm64v8.a and libgodot-cpp.android.debug.armv7.a; but now I get a lot of linker errors (below is just a part of it); maybe I missed something in the generation? :

  [35/35] Linking CXX shared library ..\..\..\..\build\intermediates\cmake\debug\obj\armeabi-v7a\libgodot_ovrmobile.so
  FAILED: cmd.exe /C "cd . && D:\software\android\ndk-bundle\toolchains\llvm\prebuilt\windows-x86_64\bin\clang++.exe  --target=armv7-none-linux-androideabi18 --gcc-toolchain=D:/software/android/ndk-bundle/toolchains/llvm/prebuilt/windows-x86_64 --sysroot=D:/software/android/ndk-bundle/toolchains/llvm/prebuilt/windows-x86_64/sysroot -fPIC -g -DANDROID -fdata-sections -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -D_FORTIFY_SOURCE=2 -march=armv7-a -mthumb -Wformat -Werror=format-security  -std=c++14 -O0 -fno-limit-debug-info  -Wl,--exclude-libs,libgcc_real.a -Wl,--exclude-libs,libatomic.a -Wl,--build-id -Wl,--fatal-warnings -Wl,--exclude-libs,libunwind.a -Wl,--no-undefined -Qunused-arguments   -Wl -shared -Wl,-soname,libgodot_ovrmobile.so -o ..\..\..\..\build\intermediates\cmake\debug\obj\armeabi-v7a\libgodot_ovrmobile.so CMakeFiles/godot_ovrmobile.dir/src/main/cpp/api/ovr_display_refresh_rate.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/api/ovr_guardian_system.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/api/ovr_init_config.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/api/ovr_input.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/api/ovr_performance.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/api/ovr_tracking_transform.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/api/ovr_utilities.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/common.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/framebuffer.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/gdnative/arvr_interface.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/gdnative/godot_ovrmobile.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/gdnative/nativescript/nativescript_common.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/gdnative/nativescript/ovr_display_refresh_rate_ns.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/gdnative/nativescript/ovr_guardian_system_ns.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/gdnative/nativescript/ovr_hand_tracking_ns.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/gdnative/nativescript/ovr_init_config_ns.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/gdnative/nativescript/ovr_input_ns.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/gdnative/nativescript/ovr_performance_ns.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/gdnative/nativescript/ovr_tracking_transform_ns.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/gdnative/nativescript/ovr_utilities_ns.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/gdnative/nativescript/ovr_vr_api_proxy_ns.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/jni/jni_common.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/jni/ovr_display_refresh_rate_jni.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/jni/ovr_guardian_system_jni.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/jni/ovr_init_config_jni.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/jni/ovr_input_jni.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/jni/ovr_mobile_plugin_jni.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/jni/ovr_mobile_plugin_wrapper.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/jni/ovr_performance_jni.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/jni/ovr_tracking_transform_jni.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/jni/ovr_utilities_jni.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/ovr_mobile_controller.cpp.o CMakeFiles/godot_ovrmobile.dir/src/main/cpp/ovr_mobile_session.cpp.o  -landroid -llog -lEGL -lGLESv3 ../../../../libs/ovr_sdk_mobile/VrApi/Libs/Android/armeabi-v7a/Debug/libvrapi.so -latomic -lm && cd ."
  D:\programming\godot\2.0_godot_oculus_mobile\plugin/src\main\cpp\api\ovr_utilities.cpp:33: error: undefined reference to 'godot::String::empty() const'

  D:\programming\godot\2.0_godot_oculus_mobile\plugin/src\main\cpp\api\ovr_utilities.cpp:34: error: undefined reference to 'godot::String::utf8() const'

...

  D:\programming\godot\2.0_godot_oculus_mobile\plugin/src\main\cpp\jni\ovr_mobile_plugin_wrapper.cpp:0: error: undefined reference to 'android_api'

  clang++: error: linker command failed with exit code 1 (use -v to see invocation)

[m4gr3d]

Did you try to clean (delete) the build directories after generating the Godot cpp bindings and attempting the build again?

[NeoSpark314]

I tried a gradlew.bat clean and manually deleted the plugin\build folder; but in both cases I still get the same linker error. But from the linker command line call I posted above above it seems to not link against the godot-cpp .so at all.

[m4gr3d]

@NeoSpark314 Do you mind restarting the entire process (all the way from checking out the branch) and provide a screenshot of all the terminal commands you enter. I'll use the screenshot and replicate exactly what you did to see if I can replicate the linker error.

[NeoSpark314]

@m4gr3d yes; I'll do this; I report back when I'm through

[NeoSpark314]

@m4gr3d I did a clean co and tried to build; now I have a new error (see last screeshots):

[m4gr3d]

@NeoSpark314 According to stack overflow the kotlin error might be caused by gradle unable to find the Android SDK. As mentioned in the post, try also setting ANDROID_HOME on your path variable.

[m4gr3d]

@NeoSpark314 In my own shell, I have ANDROID_HOME instead of ANDROID_SDK_HOME set as the environment variable.

[m4gr3d]

@NeoSpark314 Also, I didn't see it in your screenshot, but don't forget to setup the ovr_sdk_mobile directory in your freshly checked-out directory. Just ran into the error while following your steps.

[m4gr3d]

@NeoSpark314 I can confirm the issue is caused by setting ANDROID_SDK_HOME instead of ANDROID_HOME. When I changed my env variable to match yours, I got the same error.

[NeoSpark314]

@m4gr3d thanks for your help; now it builds!

[m4gr3d]

@m4gr3d thanks for your help; now it builds!

Great to hear!

It's worth adding that the migration to godot-cpp will increase build time (and binary size), but I think it's worth it as it drastically simplifies the process of adding new features/apis and our ability to leverage more of Godot apis.

[m4gr3d]

Build now works (thanks @m4gr3d). The binary file size increase feels quite large (release goes from 600kb .so to 40MB .so); I have not yet had the chance to try it out on the quest; will do a.s.a.p.

@NeoSpark314 is the final apk 40MB? When I generate the aar files, I'm getting less than 2MB

• OVRMobile-debug.aar = 1.71MB
• OVRMobile-release.aar = 1.38MB

[NeoSpark314]

No; only the .so files; maybe they are not yet stripped when generated with :generateSharedLibs; the .aar file has the same file size that you wrote (and the .so in there is 'only' 4mb)

[m4gr3d]

That's probably the case. I tested yesterday by building an apk with the debug aar file, and the apk binary size increased by ~1.5MB (so within the expected range). The aar build process most likely strips away a lot from the shared library.

@BastiaanOlij Since you have most experience with the godot-cpp build process, do you know if there are build parameters we can pass to reduce the size of the 'raw' shared libraries, or does their size not matter?

[m4gr3d]

@NeoSpark314 @BastiaanOlij I'm pausing work on this for now because of https://github.com/GodotNativeTools/godot-cpp/issues/394.