Fix particle sizes, and add tools for comparing renderers

Particles: Direct3D 9's size limit evidently isn't the documented 64 pixels; unclamped (up to 2048) they match the client's renderer. A compare view shows the left half's scene over the right half, both renderers side by side; %TEMP%\t5de-renderer-view.txt switches views and %TEMP%\t5de-renderer-shaders\fixed_function.hlsl replaces the shaders while the client runs. The renderer process runs from a copy, so the program can be replaced meanwhile. The adapter recognizes only the textures and buffers it made (others reach the client renderer unchanged) and logs the others and render targets.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

adapter/renderer_process.cpp

@@ -29,6 +29,31 @@ std::filesystem::path module_folder()
 
 std::string narrow(const std::wstring& text) { return std::filesystem::path(text).string(); }
 
+// The renderer process runs from a copy in %TEMP%\t5de-renderer, one per version of the program (by size and
+// modification time), so the program in the client's folder can be replaced (updated) while the client runs: the
+// next engine runs the new one. Copies no longer running are removed. Falls back to the program itself.
+std::filesystem::path running_copy(const std::filesystem::path& exe)
+{
+    std::error_code error;
+    const auto size = std::filesystem::file_size(exe, error);
+    const auto modified = std::filesystem::last_write_time(exe, error);
+    if (error) {
+        return exe;
+    }
+    const auto folder = std::filesystem::temp_directory_path(error) / L"t5de-renderer";
+    std::filesystem::create_directories(folder, error);
+    const auto copy = folder / std::format(L"t5de-renderer-{}-{}.exe", size, modified.time_since_epoch().count());
+    if (!std::filesystem::exists(copy, error)) {
+        for (const auto& old : std::filesystem::directory_iterator(folder, error)) {
+            std::filesystem::remove(old.path(), error); // fails, harmlessly, for copies still running
+        }
+        if (!CopyFileW(exe.c_str(), copy.c_str(), FALSE)) {
+            return exe;
+        }
+    }
+    return copy;
+}
+
 } // namespace
 
 std::unique_ptr<RendererProcess> RendererProcess::start(HWND window, protocol::View view)
@@ -64,7 +89,7 @@ std::unique_ptr<RendererProcess> RendererProcess::start(HWND window, protocol::V
     // The renderer's window goes on top of the client's 3D view: keep the client's drawing out of it.
     SetWindowLongW(window, GWL_STYLE, GetWindowLongW(window, GWL_STYLE) | WS_CLIPCHILDREN);
 
-    const auto exe = module_folder() / L"t5de-renderer.exe";
+    const auto exe = running_copy(module_folder() / L"t5de-renderer.exe");
     std::wstring command = std::format(L"\"{}\" --channel {} --parent {}", exe.wstring(), name, GetCurrentProcessId());
     STARTUPINFOW startup{.cb = sizeof(STARTUPINFOW)};
     PROCESS_INFORMATION process{};