v0.6.0: WebAssembly build with a WebGL backend (playable in the browser)

- ra3.webgl: a Web peer of Vulkan/Direct3D (SDL3 canvas + GLES3/WebGL2), with
  2D blit and the GPU terrain raymarch; GLSL ES shaders; null fallback off
  Emscripten. backend::webgl + default_backend() (webgl under Emscripten).
- Emscripten toolchain + Dockerfile.wasm + scripts/build-wasm.sh; import std,
  global -fexceptions, and Asyncify so the blocking frame loop yields to the
  browser (display::sleep_frame calls emscripten_sleep).
- apps/web/shell.html + apps/web/serve.py (Range-capable dev server).
- Assets: browsers forbid synchronous on-demand reads on the main thread (and
  FS.createLazyFile / the WasmFS fetch backend are worker-only; SDL3's Emscripten
  backend is main-thread DOM only, so the engine cannot run in a worker). The
  wasm build therefore preloads a compact per-map set via OPENRA3_WEB_ASSETS.
- New openra3 textures --map ID lists the loose terrain TGAs a map resolves to
  (terrain::resolve_texture_files, shared with load_textures_from_dir).
- Fixes: webgl heightmap used GL_R16 = 0x8229 (that is R8) -> upload rejected,
  terrain flattened to water; now 0x822A. Logger uses a stdout console sink on
  the web (stderr maps to console.error); a GL error check logs bad uploads.
- CI: wasm image + build jobs.

apps/openra3/main.cpp

@@ -95,7 +95,15 @@ namespace {
     auto setup_logging(const std::filesystem::path &exe_dir) -> void {
         namespace log = ender::log;
         log::configure({.minimum = log::level::info, .stacktrace_from = log::level::warn});
+#if defined(__EMSCRIPTEN__)
+        // The default sink writes to stderr, which the browser maps to
+        // console.error regardless of level; use stdout so INFO/WARN appear at
+        // their real level. There is no file sink on the web.
+        log::set_sinks({std::make_shared<log::console_sink>(std::cout)});
+        (void) exe_dir;
+#else
         log::add_file_sink(exe_dir / "openra3.log", {.max_file_size = 4U * 1024U * 1024U, .max_archives = 10U});
+#endif
         log::info("OpenRA3 started");
     }
 
@@ -106,13 +114,14 @@ namespace {
         std::puts("  openra3 menu                               (pick a map, then view it)");
         std::puts("  openra3 menu-preview [--out FILE.bmp]      (headless render of the menu)");
         std::puts("  openra3 maps");
+        std::puts("  openra3 textures --map ID                 (loose terrain TGAs a map uses)");
         std::puts("  openra3 skirmish [--map ID] [--frames N] [--seed N]");
         std::puts("  openra3 render [--map ID] [--frames N] [--seed N] [--zoom Z]");
         std::puts("                 [--out FILE.bmp] [--vulkan] [--no-window] [--no-sim] [--thumbnail]");
         std::puts("                 [--3d] [--cam-pitch DEG] [--cam-yaw DEG] [--cam-x U] [--cam-y U]");
         std::puts("                 [--cam-height U] [--fov DEG] [--width W] [--height H]");
         std::puts("                 [--fullscreen] [--fps N] (0 = vsync)");
-        std::puts("                 [--vulkan] [--dx11] [--dx12] [--sdl] (preferred display backend)");
+        std::puts("                 [--vulkan] [--dx11] [--dx12] [--webgl] [--sdl] (preferred display backend)");
         std::puts("assets: read from <exe_dir>/assets (extracted at build time by the openra3_assets target)");
     }
 
@@ -131,6 +140,7 @@ namespace {
     [[nodiscard]] auto display_backend_from_args(const std::vector<std::string> &args) -> ra3::display::backend {
         if (has_flag(args, "--dx11") || has_flag(args, "--d3d11")) return ra3::display::backend::d3d11;
         if (has_flag(args, "--dx12") || has_flag(args, "--d3d12")) return ra3::display::backend::d3d12;
+        if (has_flag(args, "--webgl")) return ra3::display::backend::webgl;
         if (has_flag(args, "--sdl")) return ra3::display::backend::sdl;
         return ra3::display::backend::vulkan;
     }
@@ -296,6 +306,32 @@ namespace {
         return ready;
     }
 
+    /** Print the loose terrain TGA files a map resolves to (for a wasm preload). */
+    auto command_textures(const std::vector<std::string> &args, const std::filesystem::path &assets) -> int {
+        if (!ensure_assets(assets)) return 1;
+        const auto requested = option_value(args, "--map");
+        if (!requested) {
+            std::puts("usage: openra3 textures --map ID");
+            return 2;
+        }
+        const auto maps = list_asset_maps(assets);
+        const asset_map *picked = nullptr;
+        for (const auto &map: maps) {
+            if (map.id == *requested) picked = &map;
+        }
+        if (picked == nullptr) {
+            std::printf("no map '%s'\n", requested->c_str());
+            return 2;
+        }
+        const auto parsed = ra3::terrain::parse_map(ra3::map::to_ckmp(read_file(picked->file)));
+        const auto files = ra3::terrain::resolve_texture_files(parsed, assets / "terrain");
+        std::printf("map %s: %zu resolved textures\n", picked->id.c_str(), files.size());
+        for (const auto &file: files) {
+            std::printf("%s\n", file.string().c_str());
+        }
+        return 0;
+    }
+
     auto command_maps(const std::filesystem::path &assets) -> int {
         if (!ensure_assets(assets)) return 1;
         const auto maps = list_asset_maps(assets);
@@ -574,9 +610,10 @@ namespace {
      * then the others in turn, so an unavailable backend degrades gracefully.
      * Direct3D is Windows-only; on other hosts those entries fall through.
      */
-    inline constexpr std::array<ra3::display::backend, 4> renderer_backends{ra3::display::backend::vulkan, ra3::display::backend::d3d11,
-                                                                            ra3::display::backend::d3d12, ra3::display::backend::sdl};
-    inline constexpr std::array<std::string_view, 4> renderer_names{"Vulkan", "Direct3D 11", "Direct3D 12", "SDL (software)"};
+    inline constexpr std::array<ra3::display::backend, 5> renderer_backends{ra3::display::backend::vulkan, ra3::display::backend::d3d11,
+                                                                            ra3::display::backend::d3d12, ra3::display::backend::webgl,
+                                                                            ra3::display::backend::sdl};
+    inline constexpr std::array<std::string_view, 5> renderer_names{"Vulkan", "Direct3D 11", "Direct3D 12", "WebGL", "SDL (software)"};
 
     [[nodiscard]] inline auto renderer_backend(int index) -> ra3::display::backend {
         return renderer_backends[static_cast<std::size_t>(std::clamp(index, 0, static_cast<int>(renderer_backends.size()) - 1))];
@@ -661,7 +698,7 @@ namespace {
         case 15: return s.fullscreen ? "yes" : "no";
         case 16: return std::string{fps_names[static_cast<std::size_t>(std::clamp(s.fps_index, 0, 4))]} + " fps";
         case 17: return "start";
-        case 18: return std::string{renderer_names[static_cast<std::size_t>(std::clamp(s.renderer, 0, 3))]};
+        case 18: return std::string{renderer_names[static_cast<std::size_t>(std::clamp(s.renderer, 0, 4))]};
         default: return "exit";
         }
     }
@@ -684,7 +721,7 @@ namespace {
         case 13: s.thumbnail = !s.thumbnail; break;
         case 15: s.fullscreen = !s.fullscreen; break;
         case 16: s.fps_index = (s.fps_index + delta + 5) % 5; break;
-        case 18: s.renderer = (s.renderer + delta + 4) % 4; break;
+        case 18: s.renderer = (s.renderer + delta + 5) % 5; break;
         default: break;
         }
     }
@@ -1084,7 +1121,8 @@ namespace {
         if (has_flag(args, "--vulkan")) st.settings.renderer = 0;
         if (has_flag(args, "--dx11") || has_flag(args, "--d3d11")) st.settings.renderer = 1;
         if (has_flag(args, "--dx12") || has_flag(args, "--d3d12")) st.settings.renderer = 2;
-        if (has_flag(args, "--sdl")) st.settings.renderer = 3;
+        if (has_flag(args, "--webgl")) st.settings.renderer = 3;
+        if (has_flag(args, "--sdl")) st.settings.renderer = 4;
         if (const auto value = option_value(args, "--width")) st.settings.width = std::stoi(*value);
         if (const auto value = option_value(args, "--height")) st.settings.height = std::stoi(*value);
         if (const auto value = option_value(args, "--cam-pitch")) st.settings.cam_pitch = std::stof(*value);
@@ -1243,6 +1281,7 @@ auto main(int argc, char **argv) -> int {
     if (command == "menu") return command_menu(rest, assets);
     if (command == "menu-preview") return command_menu_preview(rest, assets);
     if (command == "maps") return command_maps(assets);
+    if (command == "textures") return command_textures(rest, assets);
     if (command == "skirmish") return command_skirmish(rest, assets);
     if (command == "render") return command_render(rest, assets);
 

apps/web/serve.py

@@ -0,0 +1,107 @@
+#!/usr/bin/env python3
+"""Static file server with HTTP Range support, for the OpenRA3 wasm build.
+
+Emscripten's lazy MEMFS reads assets back as byte ranges, so the server must
+honour the ``Range`` header -- Python's stdlib ``http.server`` does not.
+
+    python3 apps/web/serve.py --root build/wasm/bin --port 8199
+    # then open http://localhost:8199/openra3.html
+
+Serve ``--root`` containing ``openra3.html/.js/.wasm``, ``assets.manifest.json``
+and the extracted ``assets/`` tree (a directory or a junction/symlink to it).
+"""
+
+import argparse
+import functools
+import os
+import re
+import sys
+from http.server import SimpleHTTPRequestHandler, ThreadingHTTPServer
+
+_RANGE = re.compile(r"bytes=(\d*)-(\d*)$")
+
+
+class RangeHandler(SimpleHTTPRequestHandler):
+    # SharedArrayBuffer (needed by the pthreads build) requires cross-origin
+    # isolation.
+    def end_headers(self):
+        self.send_header("Cross-Origin-Opener-Policy", "same-origin")
+        self.send_header("Cross-Origin-Embedder-Policy", "require-corp")
+        super().end_headers()
+
+    def send_head(self):
+        header = self.headers.get("Range")
+        if not header:
+            return super().send_head()
+
+        path = self.translate_path(self.path)
+        if os.path.isdir(path):
+            return super().send_head()
+        try:
+            handle = open(path, "rb")
+        except OSError:
+            self.send_error(404, "File not found")
+            return None
+
+        match = _RANGE.match(header.strip())
+        if not match:
+            handle.close()
+            return super().send_head()
+
+        size = os.fstat(handle.fileno()).st_size
+        start = int(match.group(1)) if match.group(1) else 0
+        end = int(match.group(2)) if match.group(2) else size - 1
+        if start > end or start >= size:
+            handle.close()
+            self.send_error(416, "Requested Range Not Satisfiable")
+            return None
+        end = min(end, size - 1)
+
+        self.send_response(206)
+        self.send_header("Content-Type", self.guess_type(path))
+        self.send_header("Accept-Ranges", "bytes")
+        self.send_header("Content-Range", f"bytes {start}-{end}/{size}")
+        self.send_header("Content-Length", str(end - start + 1))
+        self.send_header("Cache-Control", "no-store")
+        self.end_headers()
+        handle.seek(start)
+        self._remaining = end - start + 1
+        return handle
+
+    def copyfile(self, source, outputfile):
+        remaining = getattr(self, "_remaining", None)
+        if remaining is None:
+            return super().copyfile(source, outputfile)
+        try:
+            while remaining > 0:
+                chunk = source.read(min(65536, remaining))
+                if not chunk:
+                    break
+                outputfile.write(chunk)
+                remaining -= len(chunk)
+        finally:
+            self._remaining = None
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description="OpenRA3 wasm dev server")
+    parser.add_argument("--root", default="build/wasm/bin", help="directory to serve")
+    parser.add_argument("--port", type=int, default=8199)
+    parser.add_argument("--bind", default="127.0.0.1")
+    args = parser.parse_args()
+
+    if not os.path.isdir(args.root):
+        print(f"root not found: {args.root}", file=sys.stderr)
+        return 1
+    handler = functools.partial(RangeHandler, directory=args.root)
+    server = ThreadingHTTPServer((args.bind, args.port), handler)
+    print(f"serving {args.root} at http://{args.bind}:{args.port}/openra3.html")
+    try:
+        server.serve_forever()
+    except KeyboardInterrupt:
+        pass
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

apps/web/shell.html

@@ -0,0 +1,33 @@
+<!doctype html>
+<!-- Emscripten shell for OpenRA3. SDL3 (built for Emscripten) renders into the
+     canvas element below; the SCRIPT placeholder is replaced by the generated
+     loader. Note: the shell preprocessor treats a leading hash as a directive,
+     so do not begin a line with one. -->
+<html lang="en">
+<head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no">
+    <title>OpenRA3</title>
+    <style>
+        html, body { margin: 0; height: 100%; background: #1a0a08; overflow: hidden; }
+        #canvas { display: block; width: 100vw; height: 100vh; outline: none; }
+        #loading { position: absolute; inset: 0; display: flex; align-items: center; justify-content: center;
+                   color: #ecbe50; font: 16px/1.4 monospace; pointer-events: none; }
+    </style>
+</head>
+<body>
+    <canvas id="canvas" tabindex="-1" oncontextmenu="event.preventDefault()"></canvas>
+    <div id="loading">Loading OpenRA3…</div>
+    <script>
+        // Emscripten merges this into the generated Module; drop the loading
+        // placeholder once the runtime is up.
+        var Module = {
+            onRuntimeInitialized: function () {
+                var el = document.getElementById('loading');
+                if (el) el.remove();
+            }
+        };
+    </script>
+    {{{ SCRIPT }}}
+</body>
+</html>