Add BVH parallelization with Numba and mesh query infrastructure

- Refactor BVH module to use Numba JIT for parallel triangle/edge/point queries
- Add new intersection, proximity, and distance detection modules
- Add unit testing infrastructure with test runner (frontend/tests/)
- Extend asset uploader to support UV coordinates (#x5 vertex format)
- Simplify examples by removing redundant .direction() calls
- Update .gitignore to allow frontend/tests/ directory
- Integrate unit tests into Windows CI workflow

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: ryichando

.gitignore

@@ -1,5 +1,5 @@
 target
-tests
+/tests
 bin/
 requirements.txt
 .clangd

build-win-native/fast-check-all.bat

@@ -75,6 +75,21 @@ if not exist "%PYTHON%" (
     goto :error
 )
 
+REM ============================================================
+REM Run Unit Tests (equivalent to warmup.py run_tests)
+REM ============================================================
+echo === Running Unit Tests ===
+echo.
+"%PYTHON%" -c "from frontend.tests._runner_ import run_all_tests; import sys; sys.exit(0 if run_all_tests() else 1)"
+if errorlevel 1 (
+    echo.
+    echo === UNIT TESTS FAILED ===
+    goto :error
+)
+echo.
+echo === Unit Tests Passed ===
+echo.
+
 echo === Fast Check All Examples ===
 echo Using: %EXAMPLES_TXT%
 echo.

examples/curtain.ipynb

@@ -46,8 +46,6 @@
     "    obj = scene.add(\"sheet\")\n",
     "    obj.param.set(\"strain-limit\", 0.05)\n",
     "    obj.at(i * space, 0, 0)\n",
-    "    # set fiber directions for Baraff-Witkin\n",
-    "    obj.direction([0, 1, 0], [0, 0, 1])\n",
     "    # pin top edge of each sheet\n",
     "    obj.pin(obj.grab([0, 1, 0]))\n",
     "\n",

examples/drape.ipynb

@@ -55,9 +55,6 @@
     "    # pin the corners\n",
     "    obj.pin(corner)\n",
     "\n",
-    "    # set fiber directions required for Baraff-Witkin\n",
-    "    obj.direction([1, 0, 0], [0, 0, 1])\n",
-    "\n",
     "    # set the strainlimiting of 5%\n",
     "    obj.param.set(\"strain-limit\", 0.05)\n",
     "\n",

examples/hang.ipynb

@@ -33,7 +33,7 @@
     "scene = app.scene.create()\n",
     "\n",
     "# hang a sheet and pin top two corners\n",
-    "sheet = scene.add(\"sheet\").direction([1, 0, 0], [0, 1, 0])\n",
+    "sheet = scene.add(\"sheet\")\n",
     "sheet.pin(sheet.grab([-1, 1, 0]) + sheet.grab([1, 1, 0]))\n",
     "\n",
     "# set strain-limiting upper bound\n",

examples/headless.py

@@ -19,7 +19,6 @@
 for i in range(5):
     obj = scene.add("sheet")
     obj.at(i * space, 0, 0)
-    obj.direction([0, 1, 0], [0, 0, 1])
     obj.pin(obj.grab([0, 1, 0]))
     obj.param.set("strain-limit", 0.05)
 

examples/needle.ipynb

@@ -55,7 +55,7 @@
     "for i in range(n):\n",
     "    y = (i + 1) * space\n",
     "    deg = i * 90 / n\n",
-    "    obj = scene.add(\"sheet\").direction([1, 0, 0], [0, 1, 0])\n",
+    "    obj = scene.add(\"sheet\")\n",
     "    obj.at(0, y, 0).rotate(90, \"x\").rotate(deg + 5 * random.random(), \"y\")\n",
     "    obj.param.set(\"strain-limit\", 0.05).set(\"friction\", 0.5)\n",
     "\n",

examples/stack.ipynb

@@ -44,7 +44,7 @@
     "for i in range(n):\n",
     "    y = (i + 1) * space\n",
     "    deg = i * 90 / n\n",
-    "    obj = scene.add(\"sheet\").direction([1, 0, 0], [0, 0, 1])\n",
+    "    obj = scene.add(\"sheet\")\n",
     "    obj.at(0, y, 0).jitter().rotate(deg, \"y\")\n",
     "    obj.param.set(\"strain-limit\", 0.05).set(\"bend\", 2.5).set(\"friction\", 0.5)\n",
     "\n",

examples/trampoline.ipynb

@@ -37,7 +37,7 @@
     "scene = app.scene.create()\n",
     "\n",
     "# add sheet as trampoline with dynamic area coloring\n",
-    "sheet = scene.add(\"sheet\").dyn_color(\"area\", 1.0).direction([1, 0, 0], [0, 0, 1])\n",
+    "sheet = scene.add(\"sheet\").dyn_color(\"area\", 1.0)\n",
     "\n",
     "# pin the four edges of the sheet\n",
     "sheet.pin(sheet.grab([-1, 0, 0]) + sheet.grab([1, 0, 0]))\n",

frontend/__init__.py

@@ -47,7 +47,8 @@
     "sdf",
 ]
 
-from ._app_ import App, get_cache_dir
+from . import _sdf_ as sdf
+from ._app_ import App
 from ._asset_ import AssetFetcher, AssetManager, AssetUploader
 from ._decoder_ import BlenderApp, ParamDecoder, SceneDecoder
 from ._extra_ import Extra
@@ -75,5 +76,4 @@
     SessionManager,
     SessionOutput,
 )
-from ._utils_ import Utils
-from . import _sdf_ as sdf
+from ._utils_ import Utils, get_cache_dir