should prob put this on git sometime

destrum/src/FS/AssetFS.cpp

@@ -0,0 +1,68 @@
+#include <cassert>
+#include <fstream>
+#include <destrum/FS/AssetFS.h>
+
+#include "spdlog/spdlog.h"
+
+void AssetFS::Init(std::filesystem::path exeDir) {
+    Mount("engine", exeDir / "assets/engine");
+    Mount("game",   exeDir / "assets/game");
+    initialized = true;
+}
+
+void AssetFS::Mount(std::string scheme, std::filesystem::path root) {
+    spdlog::debug("Mounting assetfs scheme '{}' to root '{}'", scheme, root.string());
+    mounts.push_back({std::move(scheme), std::move(root)});
+}
+
+std::vector<uint8_t> AssetFS::ReadBytes(std::string_view vpath) {
+    assert(initialized && "AssetFS not initialized");
+    // parse "engine://path/inside"
+    auto pos = vpath.find("://");
+    if (pos == std::string_view::npos) throw std::runtime_error("bad vpath");
+
+    std::string scheme(vpath.substr(0, pos));
+    std::filesystem::path rel(std::string(vpath.substr(pos + 3)));
+
+    for (auto& m : mounts) {
+        if (m.scheme == scheme) {
+            auto full = m.root / rel;
+            return ReadFile(full);
+        }
+    }
+    throw std::runtime_error("mount not found");
+}
+
+std::filesystem::path AssetFS::GetFullPath(std::string_view vpath) const {
+    assert(initialized && "AssetFS not initialized");
+    // parse "engine://path/inside"
+    auto pos = vpath.find("://");
+    if (pos == std::string_view::npos) throw std::runtime_error("bad vpath");
+
+    std::string scheme(vpath.substr(0, pos));
+    std::filesystem::path rel(std::string(vpath.substr(pos + 3)));
+
+    for (auto& m : mounts) {
+        if (m.scheme == scheme) {
+            auto full = m.root / rel;
+            return full;
+        }
+    }
+    throw std::runtime_error("mount not found");
+}
+
+std::vector<uint8_t> AssetFS::ReadFile(const std::filesystem::path& fullPath) {
+    std::ifstream file(fullPath, std::ios::binary);
+    if (!file) {
+        throw std::runtime_error("failed to open file: " + fullPath.string());
+    }
+
+    file.seekg(0, std::ios::end);
+    std::streamsize size = file.tellg();
+    file.seekg(0, std::ios::beg);
+    std::vector<uint8_t> buffer(size);
+    if (!file.read(reinterpret_cast<char*>(buffer.data()), size)) {
+        throw std::runtime_error("failed to read file: " + fullPath.string());
+    }
+    return buffer;
+}