gltfio: Clear texture caches before loading resources (#5580)

* gltfio: Clear texture caches before loading resources

* iOS gltf-viewer: add double-tap to reload model for debugging

* iOS samples: add instructions on ASan / UBSan debugging

ios/samples/README.md

@@ -99,3 +99,17 @@ $ xcodegen
 
 within a sample folder to re-generate the Xcode project. You may need to close and re-open the
 project in Xcode to see changes take effect.
+
+## Building iOS Samples with ASan / UBSan
+
+1. Turn on ASan / UBSan in Filament's top-level CMakeLists.txt by uncommenting the following line:
+
+```
+set(EXTRA_SANITIZE_OPTIONS "-fsanitize=undefined -fsanitize=address")
+```
+
+2. In the Xcode project, navigate to Product -> Scheme -> Edit Scheme... Under the Diagnostics tab,
+   check the box next for Address Sanitizer and Undefined Behavior.
+
+3. Build Filament and run the iOS sample as usual. Any errors will cause an exception to raise and
+   diagnostics to print in the console.

ios/samples/gltf-viewer/gltf-viewer/FILViewController.mm

@@ -56,6 +56,8 @@ using namespace ktxreader;
     Texture* _iblTexture;
     IndirectLight* _indirectLight;
     Entity _sun;
+
+    UITapGestureRecognizer* _doubleTapRecognizer;
 }
 
 #pragma mark UIViewController methods
@@ -91,6 +93,10 @@ using namespace ktxreader;
 
     _server = new viewer::RemoteServer();
     _automation = viewer::AutomationEngine::createDefault();
+
+    _doubleTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(reloadModel)];
+    _doubleTapRecognizer.numberOfTapsRequired = 2;
+    [self.modelView addGestureRecognizer:_doubleTapRecognizer];
 }
 
 - (void)viewWillAppear:(BOOL)animated {
@@ -101,6 +107,8 @@ using namespace ktxreader;
     [self stopDisplayLink];
 }
 
+#pragma mark Private
+
 - (void)startDisplayLink {
     [self stopDisplayLink];
 
@@ -116,8 +124,6 @@ using namespace ktxreader;
     _displayLink = nil;
 }
 
-#pragma mark Private
-
 - (void)createRenderablesFromPath:(NSString*)model {
     // Retrieve the full path to the model in the documents directory.
     NSString* documentPath = [NSSearchPathForDirectoriesInDomains(
@@ -257,6 +263,11 @@ using namespace ktxreader;
     [self.modelView render];
 }
 
+- (void)reloadModel {
+    [self.modelView destroyModel];
+    [self createDefaultRenderables];
+}
+
 - (void)dealloc {
     delete _server;
     delete _automation;

libs/gltfio/src/ResourceLoader.cpp

@@ -342,6 +342,11 @@ bool ResourceLoader::loadResources(FFilamentAsset* asset, bool async) {
     SYSTRACE_CONTEXT();
     SYSTRACE_ASYNC_END("addResourceData", 1);
 
+    // Clear our texture caches. Previous calls to loadResources may have populated these, but the
+    // Texture objects could have since been destroyed.
+    pImpl->mBufferTextureCache.clear();
+    pImpl->mFilepathTextureCache.clear();
+
     if (asset->mResourcesLoaded) {
         return false;
     }