repair gltf_viewer drag&drop

Drag and dropping a gltf folder was broken:
- the handle didn't find the gltf file on drag&drop
- the ResourceLoader cached the asset path
- don't exit(1) when drag&dropping an invalid file

libs/gltfio/include/gltfio/ResourceLoader.h

@@ -69,9 +69,12 @@ class UTILS_PUBLIC ResourceLoader {
 public:
     using BufferDescriptor = filament::backend::BufferDescriptor;
 
-    ResourceLoader(const ResourceConfiguration& config);
+    explicit ResourceLoader(const ResourceConfiguration& config);
     ~ResourceLoader();
 
+
+    void setConfiguration(const ResourceConfiguration& config);
+
     /**
      * Feeds the binary content of an external resource into the loader's URI cache.
      *

libs/gltfio/src/ResourceLoader.cpp

@@ -74,15 +74,15 @@ enum class CacheResult {
 };
 
 struct ResourceLoader::Impl {
-    Impl(const ResourceConfiguration& config) :
+    explicit Impl(const ResourceConfiguration& config) :
         mEngine(config.engine),
         mNormalizeSkinningWeights(config.normalizeSkinningWeights),
         mGltfPath(config.gltfPath ? config.gltfPath : ""),
         mUriDataCache(std::make_shared<UriDataCache>()) {}
 
     Engine* const mEngine;
-    const bool mNormalizeSkinningWeights;
-    const std::string mGltfPath;
+    bool mNormalizeSkinningWeights;
+    std::string mGltfPath;
 
     // User-provided resource data with URI string keys, populated with addResourceData().
     // This is used on platforms without traditional file systems, such as Android, iOS, and WebGL.
@@ -320,6 +320,11 @@ ResourceLoader::~ResourceLoader() {
     delete pImpl;
 }
 
+void ResourceLoader::setConfiguration(const ResourceConfiguration& config) {
+    pImpl->mNormalizeSkinningWeights = config.normalizeSkinningWeights;
+    pImpl->mGltfPath = config.gltfPath;
+}
+
 void ResourceLoader::addResourceData(const char* uri, BufferDescriptor&& buffer) {
     pImpl->addResourceData(uri, std::move(buffer));
 }

samples/gltf_viewer.cpp

@@ -53,6 +53,8 @@
 #include <imgui.h>
 #include <filagui/ImGuiExtensions.h>
 
+#include <cgltf.h>
+
 #include <array>
 #include <fstream>
 #include <iostream>
@@ -485,6 +487,57 @@ static void onClick(App& app, View* view, ImVec2 pos) {
     });
 }
 
+static utils::Path getPathForAsset(std::string_view string) {
+    utils::Path filename{ string };
+    if (!filename.exists()) {
+        std::cerr << "file " << filename << " not found!" << std::endl;
+        return {};
+    }
+    if (filename.isDirectory()) {
+        auto files = filename.listContents();
+        for (const auto& file: files) {
+            if (file.getExtension() == "gltf" || file.getExtension() == "glb") {
+                filename = file;
+                break;
+            }
+        }
+        if (filename.isDirectory()) {
+            std::cerr << "no glTF file found in " << filename << std::endl;
+            return {};
+        }
+    }
+    return filename;
+}
+
+
+static bool checkAsset(const utils::Path& filename) {
+    // Peek at the file size to allow pre-allocation.
+    long const contentSize = static_cast<long>(getFileSize(filename.c_str()));
+    if (contentSize <= 0) {
+        std::cerr << "Unable to open " << filename << std::endl;
+        return false;
+    }
+
+    // Consume the glTF file.
+    std::ifstream in(filename.c_str(), std::ifstream::binary | std::ifstream::in);
+    std::vector<uint8_t> buffer(static_cast<unsigned long>(contentSize));
+    if (!in.read((char*) buffer.data(), contentSize)) {
+        std::cerr << "Unable to read " << filename << std::endl;
+        return false;
+    }
+
+    // Parse the glTF file and create Filament entities.
+    cgltf_options options{};
+    cgltf_data* sourceAsset;
+    cgltf_result result = cgltf_parse(&options, buffer.data(), contentSize, &sourceAsset);
+    if (result != cgltf_result_success) {
+        slog.e << "Unable to parse glTF file." << io::endl;
+        return false;
+    }
+    return true;
+};
+
+
 int main(int argc, char** argv) {
     App app;
 
@@ -496,24 +549,10 @@ int main(int argc, char** argv) {
     utils::Path filename;
     int const num_args = argc - optionIndex;
     if (num_args >= 1) {
-        filename = argv[optionIndex];
-        if (!filename.exists()) {
-            std::cerr << "file " << filename << " not found!" << std::endl;
+        filename = getPathForAsset(argv[optionIndex]);
+        if (filename.isEmpty()) {
             return 1;
         }
-        if (filename.isDirectory()) {
-            auto files = filename.listContents();
-            for (const auto& file : files) {
-                if (file.getExtension() == "gltf" || file.getExtension() == "glb") {
-                    filename = file;
-                    break;
-                }
-            }
-            if (filename.isDirectory()) {
-                std::cerr << "no glTF file found in " << filename << std::endl;
-                return 1;
-            }
-        }
     }
 
     auto loadAsset = [&app](const utils::Path& filename) {
@@ -534,14 +573,14 @@ int main(int argc, char** argv) {
 
         // Parse the glTF file and create Filament entities.
         app.asset = app.assetLoader->createAsset(buffer.data(), buffer.size());
-        app.instance = app.asset->getInstance();
-        buffer.clear();
-        buffer.shrink_to_fit();
-
         if (!app.asset) {
             std::cerr << "Unable to parse " << filename << std::endl;
             exit(1);
         }
+
+        app.instance = app.asset->getInstance();
+        buffer.clear();
+        buffer.shrink_to_fit();
     };
 
     auto loadResources = [&app] (const utils::Path& filename) {
@@ -559,6 +598,8 @@ int main(int argc, char** argv) {
             app.resourceLoader->addTextureProvider("image/png", app.stbDecoder);
             app.resourceLoader->addTextureProvider("image/jpeg", app.stbDecoder);
             app.resourceLoader->addTextureProvider("image/ktx2", app.ktxDecoder);
+        } else {
+            app.resourceLoader->setConfiguration(configuration);
         }
 
         if (!app.resourceLoader->asyncBeginLoad(app.asset)) {
@@ -1021,14 +1062,19 @@ int main(int argc, char** argv) {
     filamentApp.animate(animate);
     filamentApp.resize(resize);
 
-    filamentApp.setDropHandler([&] (std::string_view path) {
-        app.resourceLoader->asyncCancelLoad();
-        app.resourceLoader->evictResourceData();
-        app.viewer->removeAsset();
-        app.assetLoader->destroyAsset(app.asset);
-        loadAsset(path);
-        loadResources(path);
-        app.viewer->setAsset(app.asset, app.instance);
+    filamentApp.setDropHandler([&](std::string_view path) {
+        utils::Path const filename = getPathForAsset(path);
+        if (!filename.isEmpty()) {
+            if (checkAsset(filename)) {
+                app.resourceLoader->asyncCancelLoad();
+                app.resourceLoader->evictResourceData();
+                app.viewer->removeAsset();
+                app.assetLoader->destroyAsset(app.asset);
+                loadAsset(filename);
+                loadResources(filename);
+                app.viewer->setAsset(app.asset, app.instance);
+            }
+        }
     });
 
     filamentApp.run(app.config, setup, cleanup, gui, preRender, postRender);