gltfio: Add ResourceLoader evict API.

android/filament-utils-android/src/main/java/com/google/android/filament/utils/ModelViewer.kt

@@ -221,6 +221,7 @@ class ModelViewer(val engine: Engine) : android.view.View.OnTouchListener {
     fun destroyModel() {
         fetchResourcesJob?.cancel()
         resourceLoader.asyncCancelLoad()
+        resourceLoader.evictResourceData()
         asset?.let { asset ->
             this.scene.removeEntities(asset.entities)
             assetLoader.destroyAsset(asset)

android/gltfio-android/src/main/cpp/ResourceLoader.cpp

@@ -70,6 +70,13 @@ Java_com_google_android_filament_gltfio_ResourceLoader_nHasResourceData(JNIEnv*
     return status;
 }
 
+extern "C" JNIEXPORT void JNICALL
+Java_com_google_android_filament_gltfio_ResourceLoader_nEvictResourceData(JNIEnv*, jclass,
+        jlong nativeLoader) {
+    ResourceLoader* loader = (ResourceLoader*) nativeLoader;
+    loader->evictResourceData();
+}
+
 extern "C" JNIEXPORT void JNICALL
 Java_com_google_android_filament_gltfio_ResourceLoader_nLoadResources(JNIEnv*, jclass,
         jlong nativeLoader, jlong nativeAsset) {

android/gltfio-android/src/main/java/com/google/android/filament/gltfio/ResourceLoader.java

@@ -101,6 +101,15 @@ public class ResourceLoader {
         return nHasResourceData(mNativeObject, uri);
     }
 
+    /**
+     * Frees memory by evicting the URI cache that was populated via addResourceData.
+     *
+     * This can be called only after a model is fully loaded or after loading has been cancelled.
+     */
+    public void evictResourceData() {
+        nEvictResourceData(mNativeObject);
+    }
+
     /**
      * Iterates through all external buffers and images and creates corresponding Filament objects
      * (vertex buffers, textures, etc), which become owned by the asset.
@@ -161,6 +170,7 @@ public class ResourceLoader {
     private static native void nDestroyResourceLoader(long nativeLoader);
     private static native void nAddResourceData(long nativeLoader, String url, Buffer buffer,
             int remaining);
+    private static native void nEvictResourceData(long nativeLoader);
     private static native boolean nHasResourceData(long nativeLoader, String url);
     private static native void nLoadResources(long nativeLoader, long nativeAsset);
     private static native boolean nAsyncBeginLoad(long nativeLoader, long nativeAsset);

libs/gltfio/include/gltfio/ResourceLoader.h

@@ -93,6 +93,13 @@ public:
      */
     bool hasResourceData(const char* uri) const;
 
+    /**
+     * Frees memory by evicting the URI cache that was populated via addResourceData.
+     *
+     * This can be called only after a model is fully loaded or after loading has been cancelled.
+     */
+    void evictResourceData();
+
     /**
      * Loads resources for the given asset from the filesystem or data cache and "finalizes" the
      * asset by transforming the vertex data format if necessary, decoding image files, supplying

libs/gltfio/src/ResourceLoader.cpp

@@ -269,6 +269,11 @@ bool ResourceLoader::hasResourceData(const char* uri) const {
     return pImpl->mUriDataCache.find(uri) != pImpl->mUriDataCache.end();
 }
 
+void ResourceLoader::evictResourceData() {
+    // Note that this triggers BufferDescriptor callbacks.
+    pImpl->mUriDataCache.clear();
+}
+
 bool ResourceLoader::loadResources(FilamentAsset* asset) {
     FFilamentAsset* fasset = upcast(asset);
     return loadResources(fasset, false);

samples/gltf_viewer.cpp

@@ -1017,6 +1017,7 @@ int main(int argc, char** argv) {
 
     filamentApp.setDropHandler([&] (std::string path) {
         app.resourceLoader->asyncCancelLoad();
+        app.resourceLoader->evictResourceData();
         app.viewer->removeAsset();
         app.assetLoader->destroyAsset(app.asset);
         loadAsset(path);