Initial Android build support

android/.idea/.gitignore

@@ -0,0 +1,3 @@
+# Default ignored files
+/shelf/
+/workspace.xml

android/README.md

@@ -13,6 +13,8 @@ arm64-v8a arch only.
 
 Open this folder in Android Studio and build it.
 
+When you open the folder in the first time, it will take time(~20 mins) and many file downloads(e.g. gradle) will happen.
+
 ### Command line build
 
 T.B.W.

android/app/src/main/cpp/CMakeLists.txt

@@ -17,17 +17,21 @@ set(TINYUSDZ_DEP_SOURCES
 
 # Build the libhello-oboe library
 add_library(hello-tinyusdz SHARED
-        hello-tinyusdz.cc
+        jni-tinyusdz.cc
         ${TINYUSDZ_SOURCES}
         ${TINYUSDZ_DEP_SOURCES}
         )
 
 target_link_libraries(hello-tinyusdz android log)
 target_include_directories(hello-tinyusdz PRIVATE
-          ${PROJECT_SOURCE_DIR}/../../../../../src/
+        ${PROJECT_SOURCE_DIR}/../../../../../src/
         ${PROJECT_SOURCE_DIR}/../../../../../src/external/ryu
         )
 
+# Required to load .usd files from Android asset for demo purpose
+# When you embed TinyUSDZ to your own app, you are better to load .usd files from a memory and turn this define off.
+target_compile_definitions(hello-tinyusdz PRIVATE "TINYUSDZ_ANDROID_LOAD_FROM_ASSETS")
+
 # Enable optimization flags: if having problems with source level debugging,
 # disable -Ofast ( and debug ), re-enable after done debugging.
 target_compile_options(hello-tinyusdz PRIVATE -Wall -Werror "$<$<CONFIG:RELEASE>:-Ofast>")

android/app/src/main/cpp/hello-tinyusdz.cc

@@ -1,18 +0,0 @@
-#include <jni.h>
-
-#include "tinyusdz.hh"
-
-extern "C" {
-    /* 
-     * Returns:  0 - success
-     *          -1 - failed
-     */
-    JNIEXPORT jint JNICALL
-    Java_com_example_hellotinyusdz_MainActivity_createStream(
-            JNIEnv * /* env */,
-            jobject /* this */) {
-
-        /* TODO: Implement */
-        return -1;
-    }
-}

android/app/src/main/cpp/jni-tinyusdz.cc

@@ -0,0 +1,56 @@
+#include <jni.h>
+#include <android/log.h>
+#include <android/asset_manager.h>
+#include <android/asset_manager_jni.h>
+
+#include "tinyusdz.hh"
+
+// global
+tinyusdz::Scene g_scene;
+
+#ifndef TINYUSDZ_ANDROID_LOAD_FROM_ASSETS
+#error "This demo requires to load .usd file from Android Assets"
+#else
+#endif
+
+
+
+
+extern "C" {
+    /* 
+     * Returns:  0 - success
+     *          -1 - failed
+     */
+    JNIEXPORT jint JNICALL
+    Java_com_example_hellotinyusdz_MainActivity_createStream(
+            JNIEnv *env,
+            jobject obj,
+            jobject assetManager) {
+
+        tinyusdz::asset_manager = AAssetManager_fromJava(env, assetManager);
+
+        tinyusdz::USDLoadOptions options;
+
+        // load from Android asset folder
+        std::string warn, err;
+        bool ret = LoadUSDCFromFile("suzanne.usdc", &g_scene, &warn, &err, options);
+
+        if (warn.size()) {
+            __android_log_print(ANDROID_LOG_WARN, "tinyusdz", "USD load warning: %s", warn.c_str());
+        }
+
+        if (!ret) {
+            if (err.size()) {
+                __android_log_print(ANDROID_LOG_ERROR, "tinyusdz", "USD load error: %s", err.c_str());
+            }
+        }
+
+        if (ret) {
+            __android_log_print(ANDROID_LOG_INFO, "tinyusdz", "USD loaded. #of geom_meshes: %d", int(g_scene.geom_meshes.size()));
+            return int(g_scene.geom_meshes.size());
+        }
+
+        // err
+        return -1;
+    }
+}

android/app/src/main/java/com/example/hellotinyusdz/MainActivity.kt

@@ -17,6 +17,7 @@
 
 package com.example.hellotinyusdz
 
+import android.content.res.AssetManager
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
 import android.view.MotionEvent
@@ -46,10 +47,18 @@ class MainActivity : AppCompatActivity() {
 
     override fun onResume() {
         super.onResume()
-        if (createStream() != 0) {
-            val errorString : String = "ERROR"
+
+        var n = createStream(getAssets());
+
+        if (n <= 0) {
+            val errorString : String = "Failed to load USD file"
             Toast.makeText(applicationContext, errorString,Toast.LENGTH_LONG).show()
             sample_text.text = errorString
+        } else {
+            val s : String = "Loaded USD. # of geom_meshes " + n
+            Toast.makeText(applicationContext, s,Toast.LENGTH_LONG).show()
+            sample_text.text = s
+
         }
     }
 
@@ -59,7 +68,7 @@ class MainActivity : AppCompatActivity() {
 
 
     // Creates and starts Oboe stream to play audio
-    private external fun createStream() : Int
+    private external fun createStream(mgr: AssetManager) : Int
 
     companion object {
         // Used to load native code calling oboe on app startup.