CODEWITHSUNDEEP
androidc++opengl-esandroid-ndk
pemcode
pemcode

Reputation: 73

How can I create a new NativeWindow in Android NDK without needing the Android OS source code?

I want to compile an Android OpenGL console application that you can run directly from console boot Android x86, or from the Android terminal application inside Android x86 GUI.

This post ( How can I create a new NativeWindow in Android NDK? ) asks a similar question. However, the answer says to download and build the entire android source code because the tests here ( https://android.googlesource.com/platform/frameworks/base/+/refs/heads/gingerbread-release/opengl/tests ) such as ( https://android.googlesource.com/platform/frameworks/base/+/refs/heads/gingerbread-release/opengl/tests/gl_basic/gl_basic.cpp ) have dependencies such as "#include "

I want to build the application ideally with the NDK, but if necessary I could build it on Ubuntu.

gl_basic.cpp would be great, except I don't want to have to download and build the entire Android source code just to build such a tiny program (gl_basic.cpp is only 364 lines of code!)

I tried to build gl_basic.cpp with ndk-build.cmd, but I get FramebufferNativeWindow.h not found... And then if I keep downloading more header files to my local project, I eventually run into link errors. I wonder if there is an easier way to build something like gl_basic.cpp (Android OpenGL executable with a main() function) using the NDK.

PS I know the normal way to write Android apps is to create an APK, but I don't want to do that - I want a stand-alone Linux executable with main() and OpenGL that I can run from the Android Terminal Emulator application that runs inside Android... On x86 based Android (not ARM).

Also let me add that I know you can put "include $(BUILD_EXECUTABLE)" in the Android.mk file and "APP_ABI := x86" in the Application.mk file. I have no problem building an Android executable with ndk-build.cmd that runs from Android Terminal Emulator on x86 Android and prints "hello world" with printf().

The thing I have a problem with is creating such an executable with OpenGL. I think part of the magic is FramebufferNativeWindow.h, but that has its own includes too... I'm wondering if I can build something similar to gl_basic.cpp with ndk-build.cmd (or even with make and gcc on Ubuntu) that will run in Android Terminal Emulator... But I don't want to have to download and build the entire Android source tree.

Summary: how do I create a native window with headers and libraries that are included in the NDK? I know it can be done by calling android_createDisplaySurface() from libui. However, libui is not included as part of the NDK. So how can I create a native window (for use by EGL and OpenGL) from the NDK with pure C++ (no Java) code? eglCreateWindowSurface()'s 3rd arg is NativeWindowType, so I need to create a NativeWindow somehow.

Summary: My ultimate goal is to write a C++ executable with a main() function that draws an OpenGL triangle, that I can run on Android x86 console mode. No Java.

Upvotes: 3

Views: 2118

Answers (1)

Alex Cohn
Alex Cohn

Reputation: 57173

You must download all necessary #includes; you need the missing system libraries to resolve the references when you link your executable. You don't need to rebuild these libraries, you can find ready to use libs in your target device, or even from an emulator image. System libraries from /system/lib directory can easily be obtained with adb pull command.

Note that linker does not need to resolve all references: i.e. for command

ln A.o libB.a -lC -lD -o E

you only need libD.so to match the symbols from object A.o and all referenced objects in libB.a, but not for the dependencies of libC.so.

Upvotes: 1

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