diff --git a/res/textures/blocks/bazalt.png b/res/content/base/textures/blocks/bazalt.png
similarity index 100%
rename from res/textures/blocks/bazalt.png
rename to res/content/base/textures/blocks/bazalt.png
diff --git a/res/textures/blocks/blue_lamp.png b/res/content/base/textures/blocks/blue_lamp.png
similarity index 100%
rename from res/textures/blocks/blue_lamp.png
rename to res/content/base/textures/blocks/blue_lamp.png
diff --git a/res/textures/blocks/brick.png b/res/content/base/textures/blocks/brick.png
similarity index 100%
rename from res/textures/blocks/brick.png
rename to res/content/base/textures/blocks/brick.png
diff --git a/res/textures/blocks/dirt.png b/res/content/base/textures/blocks/dirt.png
similarity index 100%
rename from res/textures/blocks/dirt.png
rename to res/content/base/textures/blocks/dirt.png
diff --git a/res/textures/blocks/flower.png b/res/content/base/textures/blocks/flower.png
similarity index 100%
rename from res/textures/blocks/flower.png
rename to res/content/base/textures/blocks/flower.png
diff --git a/res/textures/blocks/glass.png b/res/content/base/textures/blocks/glass.png
similarity index 100%
rename from res/textures/blocks/glass.png
rename to res/content/base/textures/blocks/glass.png
diff --git a/res/textures/blocks/grass.png b/res/content/base/textures/blocks/grass.png
similarity index 100%
rename from res/textures/blocks/grass.png
rename to res/content/base/textures/blocks/grass.png
diff --git a/res/textures/blocks/grass_side.png b/res/content/base/textures/blocks/grass_side.png
similarity index 100%
rename from res/textures/blocks/grass_side.png
rename to res/content/base/textures/blocks/grass_side.png
diff --git a/res/textures/blocks/grass_top.png b/res/content/base/textures/blocks/grass_top.png
similarity index 100%
rename from res/textures/blocks/grass_top.png
rename to res/content/base/textures/blocks/grass_top.png
diff --git a/res/textures/blocks/green_lamp.png b/res/content/base/textures/blocks/green_lamp.png
similarity index 100%
rename from res/textures/blocks/green_lamp.png
rename to res/content/base/textures/blocks/green_lamp.png
diff --git a/res/textures/blocks/lamp.png b/res/content/base/textures/blocks/lamp.png
similarity index 100%
rename from res/textures/blocks/lamp.png
rename to res/content/base/textures/blocks/lamp.png
diff --git a/res/textures/blocks/leaves.png b/res/content/base/textures/blocks/leaves.png
similarity index 100%
rename from res/textures/blocks/leaves.png
rename to res/content/base/textures/blocks/leaves.png
diff --git a/res/textures/blocks/lightbulb.png b/res/content/base/textures/blocks/lightbulb.png
similarity index 100%
rename from res/textures/blocks/lightbulb.png
rename to res/content/base/textures/blocks/lightbulb.png
diff --git a/res/textures/blocks/metal.png b/res/content/base/textures/blocks/metal.png
similarity index 100%
rename from res/textures/blocks/metal.png
rename to res/content/base/textures/blocks/metal.png
diff --git a/res/textures/blocks/pane.png b/res/content/base/textures/blocks/pane.png
similarity index 100%
rename from res/textures/blocks/pane.png
rename to res/content/base/textures/blocks/pane.png
diff --git a/res/textures/blocks/pane_side.png b/res/content/base/textures/blocks/pane_side.png
similarity index 100%
rename from res/textures/blocks/pane_side.png
rename to res/content/base/textures/blocks/pane_side.png
diff --git a/res/textures/blocks/pane_side_2.png b/res/content/base/textures/blocks/pane_side_2.png
similarity index 100%
rename from res/textures/blocks/pane_side_2.png
rename to res/content/base/textures/blocks/pane_side_2.png
diff --git a/res/textures/blocks/pipe_hole.png b/res/content/base/textures/blocks/pipe_hole.png
similarity index 100%
rename from res/textures/blocks/pipe_hole.png
rename to res/content/base/textures/blocks/pipe_hole.png
diff --git a/res/textures/blocks/pipe_side.png b/res/content/base/textures/blocks/pipe_side.png
similarity index 100%
rename from res/textures/blocks/pipe_side.png
rename to res/content/base/textures/blocks/pipe_side.png
diff --git a/res/textures/blocks/planks.png b/res/content/base/textures/blocks/planks.png
similarity index 100%
rename from res/textures/blocks/planks.png
rename to res/content/base/textures/blocks/planks.png
diff --git a/res/textures/blocks/red_lamp.png b/res/content/base/textures/blocks/red_lamp.png
similarity index 100%
rename from res/textures/blocks/red_lamp.png
rename to res/content/base/textures/blocks/red_lamp.png
diff --git a/res/textures/blocks/rust.png b/res/content/base/textures/blocks/rust.png
similarity index 100%
rename from res/textures/blocks/rust.png
rename to res/content/base/textures/blocks/rust.png
diff --git a/res/textures/blocks/sand.png b/res/content/base/textures/blocks/sand.png
similarity index 100%
rename from res/textures/blocks/sand.png
rename to res/content/base/textures/blocks/sand.png
diff --git a/res/textures/blocks/stone.png b/res/content/base/textures/blocks/stone.png
similarity index 100%
rename from res/textures/blocks/stone.png
rename to res/content/base/textures/blocks/stone.png
diff --git a/res/textures/blocks/torch_bottom.png b/res/content/base/textures/blocks/torch_bottom.png
similarity index 100%
rename from res/textures/blocks/torch_bottom.png
rename to res/content/base/textures/blocks/torch_bottom.png
diff --git a/res/textures/blocks/torch_side.png b/res/content/base/textures/blocks/torch_side.png
similarity index 100%
rename from res/textures/blocks/torch_side.png
rename to res/content/base/textures/blocks/torch_side.png
diff --git a/res/textures/blocks/torch_top.png b/res/content/base/textures/blocks/torch_top.png
similarity index 100%
rename from res/textures/blocks/torch_top.png
rename to res/content/base/textures/blocks/torch_top.png
diff --git a/res/textures/blocks/wallpaper_s.png b/res/content/base/textures/blocks/wallpaper_s.png
similarity index 100%
rename from res/textures/blocks/wallpaper_s.png
rename to res/content/base/textures/blocks/wallpaper_s.png
diff --git a/res/textures/blocks/water.png b/res/content/base/textures/blocks/water.png
similarity index 100%
rename from res/textures/blocks/water.png
rename to res/content/base/textures/blocks/water.png
diff --git a/res/textures/blocks/wood.png b/res/content/base/textures/blocks/wood.png
similarity index 100%
rename from res/textures/blocks/wood.png
rename to res/content/base/textures/blocks/wood.png
diff --git a/res/textures/blocks/wood_top.png b/res/content/base/textures/blocks/wood_top.png
similarity index 100%
rename from res/textures/blocks/wood_top.png
rename to res/content/base/textures/blocks/wood_top.png
diff --git a/src/assets/AssetsLoader.cpp b/src/assets/AssetsLoader.cpp
index 98fe994d..dd255dac 100644
--- a/src/assets/AssetsLoader.cpp
+++ b/src/assets/AssetsLoader.cpp
@@ -7,19 +7,20 @@
 #include <memory>
 
 #include "../constants.h"
+#include "../files/engine_paths.h"
 
 using std::filesystem::path;
 using std::unique_ptr;
 
-AssetsLoader::AssetsLoader(Assets* assets, path resdir) 
-			 : assets(assets), resdir(resdir) {
+AssetsLoader::AssetsLoader(Assets* assets, const ResPaths* paths) 
+	: assets(assets), paths(paths) {
 }
 
 void AssetsLoader::addLoader(int tag, aloader_func func) {
 	loaders[tag] = func;
 }
 
-void AssetsLoader::add(int tag, const path filename, const std::string alias) {
+void AssetsLoader::add(int tag, const std::string filename, const std::string alias) {
 	entries.push(aloader_entry{ tag, filename, alias });
 }
 
@@ -37,7 +38,7 @@ bool AssetsLoader::loadNext() {
 		return false;
 	}
 	aloader_func loader = found->second;
-	bool status = loader(assets, entry.filename, entry.alias);
+	bool status = loader(assets, paths, entry.filename, entry.alias);
 	entries.pop();
 	return status;
 }
@@ -50,20 +51,19 @@ void AssetsLoader::createDefaults(AssetsLoader& loader) {
 }
 
 void AssetsLoader::addDefaults(AssetsLoader& loader) {
-	path resdir = loader.getDirectory();
-	loader.add(ASSET_SHADER, resdir/path(SHADERS_FOLDER"/main"), "main");
-	loader.add(ASSET_SHADER, resdir/path(SHADERS_FOLDER"/lines"), "lines");
-	loader.add(ASSET_SHADER, resdir/path(SHADERS_FOLDER"/ui"), "ui");
-	loader.add(ASSET_SHADER, resdir/path(SHADERS_FOLDER"/ui3d"), "ui3d");
-	loader.add(ASSET_SHADER, resdir/path(SHADERS_FOLDER"/background"), "background");
-	loader.add(ASSET_SHADER, resdir/path(SHADERS_FOLDER"/skybox_gen"), "skybox_gen");
+	loader.add(ASSET_SHADER, SHADERS_FOLDER"/main", "main");
+	loader.add(ASSET_SHADER, SHADERS_FOLDER"/lines", "lines");
+	loader.add(ASSET_SHADER, SHADERS_FOLDER"/ui", "ui");
+	loader.add(ASSET_SHADER, SHADERS_FOLDER"/ui3d", "ui3d");
+	loader.add(ASSET_SHADER, SHADERS_FOLDER"/background", "background");
+	loader.add(ASSET_SHADER, SHADERS_FOLDER"/skybox_gen", "skybox_gen");
 
-	loader.add(ASSET_ATLAS, resdir/path(TEXTURES_FOLDER"/blocks"), "blocks");
-	loader.add(ASSET_TEXTURE, resdir/path(TEXTURES_FOLDER"/menubg.png"), "menubg");
+	loader.add(ASSET_ATLAS, TEXTURES_FOLDER"/blocks", "blocks");
+	loader.add(ASSET_TEXTURE, TEXTURES_FOLDER"/menubg.png", "menubg");
 
-	loader.add(ASSET_FONT, resdir/path(FONTS_FOLDER"/font"), "normal");
+	loader.add(ASSET_FONT, FONTS_FOLDER"/font", "normal");
 }
 
-path AssetsLoader::getDirectory() const {
-	return resdir;
+const ResPaths* AssetsLoader::getPaths() const {
+	return paths;
 }
\ No newline at end of file
diff --git a/src/assets/AssetsLoader.h b/src/assets/AssetsLoader.h
index 43e3bdca..9a731780 100644
--- a/src/assets/AssetsLoader.h
+++ b/src/assets/AssetsLoader.h
@@ -3,7 +3,6 @@
 
 #include <string>
 #include <functional>
-#include <filesystem>
 #include <map>
 #include <queue>
 
@@ -12,13 +11,14 @@ const short ASSET_SHADER = 2;
 const short ASSET_FONT = 3;
 const short ASSET_ATLAS = 4;
 
+class ResPaths;
 class Assets;
 
-typedef std::function<bool(Assets*, const std::filesystem::path&, const std::string&)> aloader_func;
+typedef std::function<bool(Assets*, const ResPaths*, const std::string&, const std::string&)> aloader_func;
 
 struct aloader_entry {
 	int tag;
-	const std::filesystem::path filename;
+	const std::string filename;
 	const std::string alias;
 };
 
@@ -26,11 +26,11 @@ class AssetsLoader {
 	Assets* assets;
 	std::map<int, aloader_func> loaders;
 	std::queue<aloader_entry> entries;
-	std::filesystem::path resdir;
+	const ResPaths* paths;
 public:
-	AssetsLoader(Assets* assets, std::filesystem::path resdir);
+	AssetsLoader(Assets* assets, const ResPaths* paths);
 	void addLoader(int tag, aloader_func func);
-	void add(int tag, const std::filesystem::path filename, const std::string alias);
+	void add(int tag, const std::string filename, const std::string alias);
 
 	bool hasNext() const;
 	bool loadNext();
@@ -38,7 +38,7 @@ public:
 	static void createDefaults(AssetsLoader& loader);
 	static void addDefaults(AssetsLoader& loader);
 
-	std::filesystem::path getDirectory() const;
+	const ResPaths* getPaths() const;
 };
 
 #endif // ASSETS_ASSETS_LOADER_H
diff --git a/src/assets/asset_loaders.cpp b/src/assets/asset_loaders.cpp
index 19f69c02..ca93828b 100644
--- a/src/assets/asset_loaders.cpp
+++ b/src/assets/asset_loaders.cpp
@@ -1,8 +1,10 @@
 #include "asset_loaders.h"
 
 #include <iostream>
+#include <filesystem>
 #include "Assets.h"
 #include "../files/files.h"
+#include "../files/engine_paths.h"
 #include "../coders/png.h"
 #include "../graphics/Shader.h"
 #include "../graphics/Texture.h"
@@ -18,9 +20,10 @@ using std::filesystem::path;
 namespace fs = std::filesystem;
 
 bool assetload::texture(Assets* assets, 
-                        const path filename, 
+                        const ResPaths* paths,
+                        const string filename, 
                         const string name) {
-	Texture* texture = png::load_texture(filename.string());
+	Texture* texture = png::load_texture(paths->find(filename).string());
 	if (texture == nullptr) {
 		std::cerr << "failed to load texture '" << name << "'" << std::endl;
 		return false;
@@ -30,10 +33,11 @@ bool assetload::texture(Assets* assets,
 }
 
 bool assetload::shader(Assets* assets, 
-                        const path filename, 
-                        const string name) {
-    path vertexFile = path(filename.string()+".glslv");
-    path fragmentFile = path(filename.string()+".glslf");
+                       const ResPaths* paths,
+                       const string filename, 
+                       const string name) {
+    path vertexFile = paths->find(filename+".glslv");
+    path fragmentFile = paths->find(filename+".glslf");
     
     string vertexSource = files::read_string(vertexFile);
     string fragmentSource = files::read_string(fragmentFile);
@@ -49,13 +53,16 @@ bool assetload::shader(Assets* assets,
 }
 
 bool assetload::atlas(Assets* assets, 
-                        const path directory, 
-                        const string name) {
+                      const ResPaths* paths,
+                      const string directory, 
+                      const string name) {
 	AtlasBuilder builder;
-	for (const auto& entry : fs::directory_iterator(directory)) {
-		path file = entry.path();
+	for (const auto& file : paths->listdir(directory)) {
 		if (file.extension() == ".png") {
 			string name = file.stem().string();
+            if (builder.has(name)) {
+                continue; // skip duplicates
+            }
 			std::unique_ptr<ImageData> image (png::load_image(file.string()));
 			image->fixAlphaColor();
 			builder.add(name, image.release());
@@ -67,11 +74,13 @@ bool assetload::atlas(Assets* assets,
 }
 
 bool assetload::font(Assets* assets, 
-                        const path filename, 
-                        const string name) {
+                     const ResPaths* paths,
+                     const string filename, 
+                     const string name) {
 	vector<Texture*> pages;
 	for (size_t i = 0; i <= 4; i++) {
-        string name = filename.string() + "_" + std::to_string(i) + ".png";
+        string name = filename + "_" + std::to_string(i) + ".png"; 
+        name = paths->find(name).string();
 		Texture* texture = png::load_texture(name);
 		if (texture == nullptr) {
 			std::cerr << "failed to load bitmap font '" << name;
diff --git a/src/assets/asset_loaders.h b/src/assets/asset_loaders.h
index 408e0047..bcfec06e 100644
--- a/src/assets/asset_loaders.h
+++ b/src/assets/asset_loaders.h
@@ -2,23 +2,27 @@
 #define ASSETS_ASSET_LOADERS_H_
 
 #include <string>
-#include <filesystem>
 
+class ResPaths;
 class Assets;
 
 namespace assetload {
     bool texture(Assets* assets, 
-                 const std::filesystem::path filename, 
+                 const ResPaths* paths,
+                 const std::string filename, 
                  const std::string name);
     bool shader(Assets* assets, 
-                 const std::filesystem::path filename, 
-                 const std::string name);
-    bool atlas(Assets* assets, 
-                const std::filesystem::path directory, 
+                const ResPaths* paths,
+                const std::string filename, 
                 const std::string name);
+    bool atlas(Assets* assets,
+               const ResPaths* paths, 
+               const std::string directory, 
+               const std::string name);
     bool font(Assets* assets, 
-                const std::filesystem::path filename, 
-                const std::string name);
+              const ResPaths* paths,
+              const std::string filename, 
+              const std::string name);
 }
 
 #endif // ASSETS_ASSET_LOADERS_H_
\ No newline at end of file
diff --git a/src/coders/GLSLExtension.cpp b/src/coders/GLSLExtension.cpp
index df8e217b..fe62dd07 100644
--- a/src/coders/GLSLExtension.cpp
+++ b/src/coders/GLSLExtension.cpp
@@ -5,25 +5,22 @@
 #include "../util/stringutil.h"
 #include "../typedefs.h"
 #include "../files/files.h"
+#include "../files/engine_paths.h"
 
 using std::string;
 using std::filesystem::path;
 namespace fs = std::filesystem;
 
-path GLSLExtension::getHeaderPath(string name) {
-    return libFolder/path(name+".glsl");
-}
-
-void GLSLExtension::setLibFolder(path folder) {
-    this->libFolder = folder;
-}
-
 void GLSLExtension::setVersion(string version) {
     this->version = version;
 }
 
+void GLSLExtension::setPaths(const ResPaths* paths) {
+    this->paths = paths;
+}
+
 void GLSLExtension::loadHeader(string name) {
-    path file = getHeaderPath(name);
+    path file = paths->find("shaders/lib/"+name+".glsl");
     string source = files::read_string(file);
     addHeader(name, source);
 }
@@ -117,7 +114,6 @@ const string GLSLExtension::process(const path file, const string& source) {
                         "expected '#include <filename>' syntax");
                 }
                 string name = line.substr(1, line.length()-2);
-                path hfile = getHeaderPath(name);
                 if (!hasHeader(name)) {
                     loadHeader(name);
                 }
diff --git a/src/coders/GLSLExtension.h b/src/coders/GLSLExtension.h
index 74eb1ff8..2b6a2bc1 100644
--- a/src/coders/GLSLExtension.h
+++ b/src/coders/GLSLExtension.h
@@ -2,19 +2,21 @@
 #define CODERS_GLSL_EXTESION_H_
 
 #include <string>
+#include <vector>
 #include <unordered_map>
 #include <filesystem>
 
+class ResPaths;
+
 class GLSLExtension {
     std::unordered_map<std::string, std::string> headers;
     std::unordered_map<std::string, std::string> defines;
-    std::filesystem::path libFolder;
     std::string version = "330 core";
 
+    const ResPaths* paths = nullptr;
     void loadHeader(std::string name);
-    std::filesystem::path getHeaderPath(std::string name);
 public:
-    void setLibFolder(std::filesystem::path folder);
+    void setPaths(const ResPaths* paths);
     void setVersion(std::string version);
 
     void define(std::string name, std::string value);
@@ -30,4 +32,4 @@ public:
     const std::string process(const std::filesystem::path file, const std::string& source);
 };
 
-#endif // CODERS_GLSL_EXTESION_H_
\ No newline at end of file
+#endif // CODERS_GLSL_EXTESION_H_
diff --git a/src/engine.cpp b/src/engine.cpp
index f4369c10..b0d75ba2 100644
--- a/src/engine.cpp
+++ b/src/engine.cpp
@@ -52,29 +52,8 @@ Engine::Engine(EngineSettings& settings, EnginePaths* paths)
 
     auto resdir = paths->getResources();
     contentPacks.push_back({"base", resdir/path("content/base")});
-    {
-        ContentBuilder contentBuilder;
-	    setup_definitions(&contentBuilder);
-        for (auto& pack : contentPacks) {
-	        ContentLoader loader(pack.folder);
-            loader.load(&contentBuilder);
-        }
-        content.reset(contentBuilder.build());
-    }
-    Shader::preprocessor->setLibFolder(paths->getResources()/path("shaders/lib"));
+    loadContent();
 
-	assets = new Assets();
-	std::cout << "-- loading assets" << std::endl;
-	AssetsLoader loader(assets, paths->getResources());
-	AssetsLoader::createDefaults(loader);
-	AssetsLoader::addDefaults(loader);
-	while (loader.hasNext()) {
-		if (!loader.loadNext()) {
-			delete assets;
-			Window::terminate();
-			throw initialize_error("could not to initialize assets");
-		}
-	}
 	Audio::initialize();
 	gui = new GUI();
     if (settings.ui.language == "auto") {
@@ -120,7 +99,7 @@ void Engine::mainloop() {
 		gui->act(delta);
 		screen->update(delta);
 		screen->draw(delta);
-		gui->draw(&batch, assets);
+		gui->draw(&batch, assets.get());
 
 		Window::swapInterval(settings.display.swapInterval);
 		Window::swapBuffers();
@@ -135,7 +114,7 @@ Engine::~Engine() {
 	Audio::finalize();
 
 	std::cout << "-- shutting down" << std::endl;
-	delete assets;
+    assets.reset();
 	Window::terminate();
 	std::cout << "-- engine finished" << std::endl;
 }
@@ -149,7 +128,7 @@ EngineSettings& Engine::getSettings() {
 }
 
 Assets* Engine::getAssets() {
-	return assets;
+	return assets.get();
 }
 
 void Engine::setScreen(shared_ptr<Screen> screen) {
@@ -173,3 +152,33 @@ void Engine::setLanguage(string locale) {
 	langs::setup(paths->getResources(), locale, contentPacks);
 	menus::create_menus(this, gui->getMenu());
 }
+
+void Engine::loadContent() {
+    auto resdir = paths->getResources();
+    ContentBuilder contentBuilder;
+    setup_definitions(&contentBuilder);
+    
+    vector<path> resRoots;
+    for (auto& pack : contentPacks) {
+        ContentLoader loader(pack.folder);
+        loader.load(&contentBuilder);
+        resRoots.push_back(pack.folder);
+    }
+    content.reset(contentBuilder.build());
+    resPaths.reset(new ResPaths(resdir, resRoots));
+
+    Shader::preprocessor->setPaths(resPaths.get());
+
+	assets.reset(new Assets());
+	std::cout << "-- loading assets" << std::endl;
+	AssetsLoader loader(assets.get(), resPaths.get());
+	AssetsLoader::createDefaults(loader);
+	AssetsLoader::addDefaults(loader);
+	while (loader.hasNext()) {
+		if (!loader.loadNext()) {
+			assets.reset();
+			Window::terminate();
+			throw initialize_error("could not to initialize assets");
+		}
+	}
+}
diff --git a/src/engine.h b/src/engine.h
index b2f9d199..cc544bf1 100644
--- a/src/engine.h
+++ b/src/engine.h
@@ -8,13 +8,15 @@
 #include "typedefs.h"
 #include "settings.h"
 
+#include "assets/Assets.h"
 #include "content/Content.h"
 #include "content/ContentPack.h"
+#include "files/engine_paths.h"
 
-class Assets;
 class Level;
 class Screen;
 class EnginePaths;
+class ResPaths;
 
 namespace gui {
 	class GUI;
@@ -26,12 +28,13 @@ public:
 };
 
 class Engine {
-	Assets* assets;
+	std::unique_ptr<Assets> assets = nullptr;
 	std::shared_ptr<Screen> screen = nullptr;
     std::vector<ContentPack> contentPacks;
 	EngineSettings& settings;
 	std::unique_ptr<Content> content = nullptr;
 	EnginePaths* paths;
+    std::unique_ptr<ResPaths> resPaths = nullptr;
 
 	uint64_t frame = 0;
 	double lastTime = 0.0;
@@ -54,6 +57,7 @@ public:
 	const Content* getContent() const;
     std::vector<ContentPack>& getContentPacks();
 	void setLanguage(std::string locale);
+    void loadContent();
 };
 
 #endif // SRC_ENGINE_H_
\ No newline at end of file
diff --git a/src/files/engine_paths.cpp b/src/files/engine_paths.cpp
index e5769491..6ff65b22 100644
--- a/src/files/engine_paths.cpp
+++ b/src/files/engine_paths.cpp
@@ -8,6 +8,7 @@
 
 namespace fs = std::filesystem;
 using std::string;
+using std::vector;
 using fs::path;
 
 path EnginePaths::getUserfiles() const {
@@ -56,3 +57,38 @@ void EnginePaths::setUserfiles(path folder) {
 void EnginePaths::setResources(path folder) {
 	this->resources = folder;
 }
+
+ResPaths::ResPaths(path mainRoot, vector<path> roots) 
+    : mainRoot(mainRoot), roots(roots) {
+}
+
+path ResPaths::find(const string& filename) const {
+    for (auto& root : roots) {
+        path file = root / path(filename);
+        if (fs::exists(file)) {
+            return file;
+        }
+    }
+    return mainRoot / path(filename);
+}
+
+vector<path> ResPaths::listdir(const string& folderName) const {
+    vector<path> entries;
+    for (auto& root : roots) {
+        path folder = root / path(folderName);
+        if (!fs::is_directory(folder))
+            continue;
+        for (const auto& entry : fs::directory_iterator(folder)) {
+            entries.push_back(entry.path());
+        }
+    }
+    {
+        path folder = mainRoot / path(folderName);
+        if (!fs::is_directory(folder))
+            return entries;
+        for (const auto& entry : fs::directory_iterator(folder)) {
+            entries.push_back(entry.path());
+        }
+    }
+    return entries;
+}
diff --git a/src/files/engine_paths.h b/src/files/engine_paths.h
index e9095258..62f02b38 100644
--- a/src/files/engine_paths.h
+++ b/src/files/engine_paths.h
@@ -2,6 +2,7 @@
 #define FILES_ENGINE_PATHS_H_
 
 #include <string>
+#include <vector>
 #include <filesystem>
 
 class EnginePaths {
@@ -19,4 +20,15 @@ public:
     void setResources(std::filesystem::path folder);
 };
 
+class ResPaths {
+    std::filesystem::path mainRoot;
+    std::vector<std::filesystem::path> roots;
+public:
+    ResPaths(std::filesystem::path mainRoot,
+             std::vector<std::filesystem::path> roots);
+    
+    std::filesystem::path find(const std::string& filename) const;
+    std::vector<std::filesystem::path> listdir(const std::string& folder) const;
+};
+
 #endif // FILES_ENGINE_PATHS_H_
\ No newline at end of file
diff --git a/src/graphics/Atlas.cpp b/src/graphics/Atlas.cpp
index a49bbeaa..b4a0077b 100644
--- a/src/graphics/Atlas.cpp
+++ b/src/graphics/Atlas.cpp
@@ -41,15 +41,20 @@ ImageData* Atlas::getImage() const {
 
 void AtlasBuilder::add(string name, ImageData* image) {
     entries.push_back(atlasentry{name, shared_ptr<ImageData>(image)});
+    names.insert(name);
+}
+
+bool AtlasBuilder::has(string name) const {
+    return names.find(name) != names.end();
 }
 
 Atlas* AtlasBuilder::build(uint extrusion, uint maxResolution) {
     unique_ptr<uint[]> sizes (new uint[entries.size() * 2]);
-    for (uint i = 0; i < entries.size(); i++) {
-        auto& entry = entries[i];
+    uint index = 0;
+    for (auto& entry : entries) {
         auto image = entry.image;
-        sizes[i*2] = image->getWidth();
-        sizes[i*2+1] = image->getHeight();
+        sizes[index++] = image->getWidth();
+        sizes[index++] = image->getHeight();
     }
     LMPacker packer(sizes.get(), entries.size()*2);
     sizes.reset(nullptr);
diff --git a/src/graphics/Atlas.h b/src/graphics/Atlas.h
index 28168cef..110caa79 100644
--- a/src/graphics/Atlas.h
+++ b/src/graphics/Atlas.h
@@ -1,6 +1,7 @@
 #ifndef GRAPHICS_ATLAS_H_
 #define GRAPHICS_ATLAS_H_
 
+#include <set>
 #include <string>
 #include <memory>
 #include <vector>
@@ -33,10 +34,12 @@ struct atlasentry {
 };
 
 class AtlasBuilder {
-    std::vector<atlasentry> entries;   
+    std::vector<atlasentry> entries;
+    std::set<std::string> names;
 public:
     AtlasBuilder() {}
     void add(std::string name, ImageData* image);
+    bool has(std::string name) const;
 
     Atlas* build(uint extrusion, uint maxResolution=8192);
 };