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How do I build the arcore camera_utility shared library in NDK-BUILD?

I'm trying to build the 'arcore camera utility' library in NDK_BUILD, here: https://github.com/google-ar/arcore-unity-sdk/tree/master/Assets/GoogleARCore/Examples/ComputerVision/Plugins/src
Using this guide: https://yeephycho.github.io/2016/10/20/How-to-Use-NDK-to-Build-A-Shared-Android_Native-Library/ I was at least able to get it to compile in a libarcore_camera_utility.so file. Not only that but it was actually recognized by my app on the phone and instead of getting a DLL missing error I got the error: "EntryPointNotFoundException: Unable to find an entry point named 'TextureReader_create' in 'arcore_camera_utility'." which means it at least found the file, now.
The filesize of the .so is only 6k so it seems like I'm not compiling it correctly as the already working 32bit version that comes with the package is 100k, based on this question it seems like I'm leaving something out?: Entry point not found, Android .so file
My Android.mk file is:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := arcore_camera_utility_shared
LOCAL_C_INCLUDES += \
LOCAL_SRC_FILES := camera_utility.cc gl_utility.cc texture_reader.cc
include $(BUILD_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := arcore_camera_utility
LOCAL_WHOLE_STATIC_LIBRARIES := arcore_camera_utility_shared
include $(BUILD_SHARED_LIBRARY)
And my Application.mk file contains:
APP_ABI := arm64-v8a
APP_PLATFORM := android-24
APP_STL := c++_static
APP_BUILD_SCRIPT := ./jni/Android.mk
Am I building it in such a way as to leave the code out?

To compile arcore_camera_utility for the arm 64bit target-
1.) Create a new directory called 'arcorelibrary', then a subdirectory called 'jni'
2.) Download this zip: https://github.com/google-ar/arcore-unity-sdk/blob/master/Assets/GoogleARCore/Examples/ComputerVision/Plugins/src/arcore_camera_utility.zip
3.) get the three .cc files and the three .h files and place them in the jni directory
4.) Create a file called 'Android.mk' and place it in the jni directory, with the following contents:
LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE:= arcore_camera_utility_static
LOCAL_SRC_FILES:= camera_utility.cc gl_utility.cc texture_reader.cc
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
LOCAL_EXPORT_LDLIBS := -llog -landroid -lEGL -lGLESv2 -lGLESv3
include $(BUILD_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := arcore_camera_utility
LOCAL_WHOLE_STATIC_LIBRARIES := arcore_camera_utility_static
include $(BUILD_SHARED_LIBRARY)
5.) Create a file called 'Application.mk' and place it in the jni directory, with the following contents:
APP_ABI := arm64-v8a
APP_PLATFORM := android-24
APP_STL := c++_static
APP_BUILD_SCRIPT := ./jni/Android.mk
6.) Download Android NDK and unzip somewhere (The version you need depends on which Unity version you're using) https://developer.android.com/ndk/downloads/older_releases.html
7.) Open a terminal or powershell, go to the root directory (arcorelibrary) of your project
8.) Create a path to where ever you unzipped Android NDK (Powershell example):
$env:Path += ";C:\[where-ever-you-unzipped]\android-ndk-r13b-windows-x86_64\android-ndk-r13b"
9.) Run:
ndk-build.cmd

Android NDK - Additional Include Directories

I am using the Android NDK to build a shared library. I have include a snippet from my Android.mk file that is causing me a few issues.
LOCAL_PATH := $(call my-dir)
..#other module here
..#other module here
include $(CLEAR_VARS)
LOCAL_MODULE := spatialite
LOCAL_C_INCLUDES := ../../../projects/externalappsdk/include
LOCAL_SRC_FILES := sqlite3.c \
spatialite.c
include $(BUILD_SHARED_LIBRARY)
My spatialite.c file includes some header files that are located in a folder that is external to the application project folder. I have included that folder in LOCAL_C_INCLUDES as shown above, but on running ndk-build, it still cannot locate these includes. What is the correct way of allowing the ndk-build command to identify where these includes are located. Any help will be greatly appreaciated.
UPDATE:
I wanted to add that spatialite itself need not be visible to the Java layer. I will thereafter be building another module which uses spatialite. I am not sure if this makes a difference to the way I declare the module on the Android.mk file.
The compiler output is shown below:
jni/spatialite.c:102:20: fatal error: geos_c.h: No such file or directory
#include
The .h file that is being imported in spatialite.c is located at C:/projects/externalappsdk/include. The spatialite.c and Android.mk are located at C:/mobile/myandroidproject/jni/
The include directive within my spatialite.c file is shown below:
#ifndef OMIT_GEOS /* including GEOS */
#include <geos_c.h>
#endif
ANSWER:
I managed to get this working using help from the answers provided by Chris which I have accepted. However, I had to make one change to the Android.mk file as is shown below:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := spatialite
LOCAL_C_INCLUDES := ../../projects/externalappsdk/include
LOCAL_SRC_FILES := sqlite3.c \
spatialite.c
include $(BUILD_SHARED_LIBRARY)
Note, that the LOCAL_C_INCLUDES goes two levels back instead of three.

Without a
LOCAL_PATH := $(call my-dir)
At the top of the Android.mk, I was unable to build a replica of your project as described, however the error was different than your report - without that directive the compiler was searching for the C source files in an NDK system directory rather in the jni/ folder.
$ cd mobile/myandroidproject/jni
$ ndk-build
Compile thumb : spatialite <= spatialite.c
SharedLibrary : libspatialite.so
Install : libspatialite.so => libs/armeabi/libspatialite.so
File: ./mobile/myandroidproject/jni/Android.mk
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := spatialite
LOCAL_C_INCLUDES := ../../../projects/externalappsdk/include
LOCAL_SRC_FILES := sqlite3.c \
spatialite.c
include $(BUILD_SHARED_LIBRARY)
File: ./mobile/myandroidproject/jni/spatialite.c
#include <geos_c.h>
File: ./mobile/myandroidproject/jni/sqlite3.c
//empty file
File: ./projects/externalappsdk/include/geos_c.h
//empty file
At minimum you should add the LOCAL_PATH line to your Android.mk
If that does not solve the problem, then please update your question with any differences between your project structure and my recreation of it.

Use LOCAL_EXPORT_C_INCLUDE_DIRS instead of LOCAL_C_INCLUDES

How to create .so (Shared Object library file) from .c (C file) for Arm Processor?

I wanted to create a Prebuilt Shared library .so from .c file for ARM processor. Kindly give me some steps to do this and also how to include and access its functions in android.

You are looking for:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := my_static_lib
LOCAL_C_INCLUDES := src
LOCAL_SRC_FILES := src/main_main.c
# Use this one to build a *.a file - static library
include $(BUILD_STATIC_LIBRARY)
# Use this one to build a *.so file - a shared library
include $(BUILD_SHARED_LIBRARY)

Android.mk How to use wildcard to include all .cpp files?

This is my directory structure...
> Classes [dir]
> ---subdir1
> ------ some .cpp and .h files
> ---subdir2
> ------ some .cpp and .h files
> ---more .cpp and .h files
> ---Android.mk
This is the code for Android.mk
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := game_logic_static
LOCAL_MODULE_FILENAME := libgame_logic
LOCAL_SRC_FILES := AppDelegate.cpp \
HelloWorldScene.cpp
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
LOCAL_STATIC_LIBRARIES := png_static_prebuilt
LOCAL_STATIC_LIBRARIES += xml2_static_prebuilt
LOCAL_STATIC_LIBRARIES += jpeg_static_prebuilt
LOCAL_WHOLE_STATIC_LIBRARIES += cocos2dx_static
LOCAL_SHARED_LIBRARIES := cocosdenshion_shared
include $(BUILD_STATIC_LIBRARY)
$(call import-module,cocos2dx/platform/third_party/android/modules/libpng)
$(call import-module,cocos2dx/platform/third_party/android/modules/libxml2)
$(call import-module,cocos2dx/platform/third_party/android/modules/libjpeg)
Can anyone post the correct code (complete if possible) for Android.mk so all .cpp will be compiled in Class directory? Thanks!
Note: Trying to develop cocos2d-x Android with Eclipse
More notes: I already tried these to no avail:
Android.mk file - including all source files in different folders and
subfolders How to write android.mk file with source files in
subdirectories? Android.mk, include all cpp files

ndk-build can't find files under jni directory

I have a very simple test project. Basically one native c file under jni (jni is
under the root of the project, in the same directory as 'src' 'res' etc). The make
file is the basically the simplest:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := native
LOCAL_SRC_FILES := native.c
include $(BUILD_SHARED_LIBRARY)
Error message is: make: * No rule to make target ` '/native.c'. needed by...
Obviously ndk-build was trying to find the file under root. If I copy the file
to the root '/' or if I specify the full path of 'native.c' in the make file,
then things are ok.
I also tried to output $LOCAL_PATH by $(warning, '$(LOCAL_PATH)') and found no problem.

Create Android.mk with the following content:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := native
LOCAL_SRC_FILES := native.c
include $(BUILD_SHARED_LIBRARY)
Put native.c in the same folder where your Android.mk is.
Run ndk-build
You will have the output as follows:
D:\12314\jni>ndk-build
"Compile thumb : native <= native.c
SharedLibrary : libnative.so
Install : libnative.so => libs/armeabi/libnative.so