feat(gl): OpenGL 4.1 and the ludic.render3d renderer

`Gl.*` binds the whole OpenGL 4.1 core API — every entry point of the
platform gl3.h with every GL_* constant, generated by `ludic-dev glgen`
with per-call ABI thunks. Windowed builds get an NSOpenGLContext on the
existing window at Retina resolution; headless builds render into an
offscreen CGL context, so a program that uses Gl.* renders and
screenshots identically under the test harness. It links gl.ll, the
thunks and OpenGL.framework only when used; every other build stays
byte-identical.

packages/ludic.render3d is a physically based renderer written on that
surface: HDRI image-based lighting, GPU-generated terrain with scanned
PBR materials, CDLOD, cascaded shadows, glTF with skinning, instanced
vegetation with impostors, procedural grass, water, SSAO, and an HDR
pipeline with bloom, auto-exposure and ACES.

It also carries this session's work on it: the terrain at half its cost
(10.3 -> 5.4 ms of frame), the streaming hitch that got worse the longer
you played, a resize that emptied the world, and the packaging that lets
a game use the renderer from its own repository — `ludic assets`, the
material manifest shipping with the package, and shader lookup falling
back to the install root. See changes/ for each, with its numbers.

The camping game that drove all of it has moved out to its own
repository, Maroon Lake; examples/rendering/smooth.ludic stays as the
renderer's example here.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

selfhost/backend/emit_call.ludic

@@ -875,6 +875,20 @@ function emit_ns_call(ns: pointer, meth: pointer, e: Node) -> Val {
   # #62: a package-provided namespace (declared with @Namespace(Foo)) that none
   # of the hardcoded core blocks matched — alias Foo.method to the bare function
   # foo_method (positional args), the same generic path the core aliases use.
+  # Gl.* — OpenGL (runtime/native/gl.ludic + the generated gl_api.ludic): the
+  # 478 gl3.h entry points bound as externs gl_<snake_name>, plus the Ludic
+  # helpers (gl_open / gl_swap / gl_screenshot / gl_program / …). Labels are the
+  # declaration's parameter names, so `Gl.clear_color(red: 0.1, …)` works.
+  if (ns == "Gl") and (bare == null) {
+    bare = "gl_" + meth
+    var gdecl = find_fn(bare)
+    if (gdecl == null) { gdecl = find_extern(bare) }
+    if (gdecl != null) {
+      let gnames = param_labels(gdecl)
+      var gi = 0
+      while gi < len(gnames) { push(labels, gnames[gi]);  gi += 1 }
+    }
+  }
   if (bare == null) and is_registered_namespace(ns) {
     bare = ns_lower(ns) + ("_") + meth
     # #76: a namespace declared with a block controls its public surface — an

selfhost/frontend/parse.ludic

@@ -249,6 +249,8 @@ function p_postfix() -> Node {
       if e.a.kind == E_ID and e.a.s == "Audio" { g_uses_audio = true }
       # Http.* (#6) — any Http method splices the HTTP client runtime.
       if e.a.kind == E_ID and e.a.s == "Http" { g_uses_http = true }
+      # Gl.* — any Gl method splices the OpenGL runtime (and links the GL backend).
+      if e.a.kind == E_ID and e.a.s == "Gl" { g_uses_gl = true }
       # Tween.to/chain/delay/value/stop/parallel (#48): the fluent stateful handles
       # live in tween.ludic, advanced by an engine-owned system each Update tick.
       if e.a.kind == E_ID and e.a.s == "Tween" and (e.s == "to" or e.s == "chain" or e.s == "delay" or e.s == "value" or e.s == "stop" or e.s == "parallel") { g_uses_tween_rt = true }
@@ -636,6 +638,7 @@ var g_uses_tween_rt: bool = false  # Tween.to/chain/delay/… (#48) -> splice tw
 var g_uses_fx: bool = false       # Fx.sparks/number/clear -> splice fx.ludic; fx_tick each Update, fx_draw each Render
 var g_uses_audio: bool = false    # Audio.* (#22) -> splice audio.ludic; a windowed build also links audio.ll + AVFoundation
 var g_uses_http:  bool = false    # Http.* (#6) -> splice http.ludic; links http.ll + Foundation (macOS)
+var g_uses_gl:    bool = false    # Gl.* -> splice gl.ludic (+ generated gl_api.ludic); links gl.ll + gl_thunks.ll + OpenGL
 # issue #64: functions marked @System(Phase) in a prebuilt binary module — the
 # compiler registers each with the host at load (it supplies the fn address,
 # which Ludic source cannot take). Parallel arrays: fn name -> phase name.
@@ -1123,6 +1126,14 @@ function maybe_splice_runtime() -> void {
     do_import("runtime/native/http.ludic")
     cur_dir = saved
   }
+  # Gl.*: splice the OpenGL surface (gl.ludic + the generated gl_api.ludic). The
+  # native calls are the linked GL entry points themselves; the window attach is
+  # is_windowed()-guarded, so a headless build renders into an offscreen context.
+  if g_uses_gl {
+    cur_dir = ""
+    do_import("runtime/native/gl.ludic")
+    cur_dir = saved
+  }
   # Anim.play/Motion.to sugar (#48): the writes live in systems.ludic and use the
   # reflection ABI, so splice it and force the world table even when the game does
   # not otherwise trip uses_engine_systems.
@@ -1193,6 +1204,7 @@ function parse_program() -> void {
   g_onlisten = new []Node
   g_toggled_layers = new []pointer
   g_uses_regex = false
+  g_uses_gl = false
   g_uses_bignum = false
   g_uses_dict = false
   g_uses_numeric = false

selfhost/main.ludic

@@ -180,6 +180,13 @@ entry {
     let http = join_path(home, "runtime/native/http.ll")
     cmd = `{cmd} {http} -Wl,-needed_framework,Foundation`
   }
+  # Gl.* links the OpenGL backend: gl.ll (offscreen contexts, float helpers), the
+  # generated per-entry-point ABI thunks, and OpenGL.framework. Windowed or not.
+  if g_uses_gl {
+    let gl = join_path(home, "runtime/native/gl.ll")
+    let glt = join_path(home, "runtime/native/gl_thunks.ll")
+    cmd = `{cmd} {gl} {glt} -framework OpenGL`
+  }
   cmd = `{cmd} -o {out}`
 
   let rc = run(cmd)