Fix demo hub GUI docking and pendulum setup

Author: jslee02

.gitignore

@@ -85,6 +85,7 @@ gh-pages/
 
 # ImGui configuration
 imgui.ini
+DART_Demo_Hub__Python_.ini
 
 # Temporary directory for dependencies
 .deps/

pixi.toml

@@ -378,7 +378,10 @@ config-py = { cmd = [
   { arg = "build_type", default = "Release" },
 ] }
 
-py-ex = { cmd = ["python", "scripts/run_py_example.py"], depends-on = [
+py-ex = { cmd = [
+  "python",
+  "scripts/run_py_example.py",
+], depends-on = [
   "build-py-dev",
 ], env = { BUILD_TYPE = "Release", LD_LIBRARY_PATH = "$CONDA_PREFIX/lib:${LD_LIBRARY_PATH:-}" } }
 

python/demo_hub/gui/app.py

@@ -69,6 +69,10 @@ def _simulate(state: GuiState) -> None:
 
 
 def _render(state: GuiState) -> None:  # pragma: no cover - manual UI
+    io = imgui.get_io()
+    io.config_flags |= imgui.ConfigFlags_.docking_enable
+    imgui.dock_space_over_viewport(0, imgui.get_main_viewport())
+
     _simulate(state)
 
     imgui.begin("Demo Hub")

python/demo_hub/gui/viewport.py

@@ -42,13 +42,13 @@ def draw_topdown(name: str, segments: Iterable[Segment2D], size=(0, 0)) -> None:
 
     def project(pt):
         x, z = pt
-        return offset_x + (x - center_x) * scale, offset_z - (z - center_z) * scale
+        return imgui.ImVec2(offset_x + (x - center_x) * scale, offset_z - (z - center_z) * scale)
 
     for seg in segs:
         c = seg.color
         col = imgui.get_color_u32(imgui.ImVec4(c[0], c[1], c[2], 1.0))
         p0 = project(seg.start)
         p1 = project(seg.end)
-        draw_list.add_line(p0[0], p0[1], p1[0], p1[1], col, thickness=2.0)
+        draw_list.add_line(p0, p1, col, thickness=2.0)
 
     imgui.end()

python/demo_hub/scenes/pendulum/scene.py

@@ -109,17 +109,15 @@ def _build_chain(self, pendulum: dart.dynamics.Skeleton) -> None:
         inertia = self._make_link_inertia(length, radius, mass)
 
         # Root ball joint at the origin.
-        ball_props = dart.dynamics.BallJointProperties()
-        ball_props.mName = "root_joint"
-        ball_props.mRestPositions = [0.0, 0.0, 0.0]
-        ball_props.mSpringStiffnesses = [1.5, 1.5, 1.5]
-        ball_props.mDampingCoefficients = [0.02, 0.02, 0.02]
-
-        root_body_props = dart.dynamics.BodyNodeProperties()
-        root_body_props.mName = "link0"
-        root_body_props.mInertia = inertia
-
-        root_joint, root_body = pendulum.createBallJointAndBodyNodePair(None, ball_props, root_body_props)
+        root_joint, root_body = pendulum.createBallJointAndBodyNodePair(None)
+        root_joint.setName("root_joint")
+        for i in range(3):
+            root_joint.setRestPosition(i, 0.0)
+            root_joint.setSpringStiffness(i, 1.5)
+            root_joint.setDampingCoefficient(i, 0.02)
+
+        root_body.setName("link0")
+        root_body.setInertia(inertia)
         self._attach_geometry(root_body, radius, length)
 
         parent = root_body

scripts/run_py_example.py

@@ -8,45 +8,47 @@
 
 
 def _resolve_example(args: list[str]) -> tuple[str, list[str]]:
-  """Return (example, remaining_args) picking the first non-flag arg or EXAMPLE env."""
-  remaining = list(args)
-  if remaining and not remaining[0].startswith("-"):
-    example = remaining.pop(0)
-  else:
-    example = os.environ.get("EXAMPLE", "hello_world")
-  while remaining and remaining[0] == "--":
-    remaining.pop(0)
-  return example, remaining
+    """Return (example, remaining_args) picking the first non-flag arg or EXAMPLE env."""
+    remaining = list(args)
+    if remaining and not remaining[0].startswith("-"):
+        example = remaining.pop(0)
+    else:
+        example = os.environ.get("EXAMPLE", "hello_world")
+    while remaining and remaining[0] == "--":
+        remaining.pop(0)
+    return example, remaining
 
 
 def main(argv: list[str]) -> int:
-  repo_root = Path(__file__).resolve().parent.parent
-  example, remaining = _resolve_example(argv)
-
-  script = repo_root / "python" / "examples" / example / "main.py"
-  if not script.exists():
-    sys.stderr.write(f"Python example not found: {script}\n")
-    return 1
-
-  build_type = os.environ.get("BUILD_TYPE", "Release")
-  env_name = os.environ.get("PIXI_ENVIRONMENT_NAME", "default")
-  py_path = repo_root / "build" / env_name / "cpp" / build_type / "python"
-
-  env = os.environ.copy()
-  existing = env.get("PYTHONPATH", "")
-  env["PYTHONPATH"] = f"{py_path}:{existing}" if existing else str(py_path)
-  # Ensure conda libs (glfw, imgui, OpenGL) are ahead of system paths.
-  conda_prefix = env.get("CONDA_PREFIX")
-  if conda_prefix:
-    ld_paths = env.get("LD_LIBRARY_PATH", "")
-    env["LD_LIBRARY_PATH"] = f"{conda_prefix}/lib:{ld_paths}" if ld_paths else f"{conda_prefix}/lib"
-    preload = env.get("LD_PRELOAD", "")
-    glfw_lib = f"{conda_prefix}/lib/libglfw.so"
-    env["LD_PRELOAD"] = f"{glfw_lib}:{preload}" if preload else glfw_lib
-
-  cmd = [sys.executable, str(script), *remaining]
-  return subprocess.call(cmd, env=env, cwd=repo_root)
+    repo_root = Path(__file__).resolve().parent.parent
+    example, remaining = _resolve_example(argv)
+
+    script = repo_root / "python" / "examples" / example / "main.py"
+    if not script.exists():
+        sys.stderr.write(f"Python example not found: {script}\n")
+        return 1
+
+    build_type = os.environ.get("BUILD_TYPE", "Release")
+    env_name = os.environ.get("PIXI_ENVIRONMENT_NAME", "default")
+    py_path = repo_root / "build" / env_name / "cpp" / build_type / "python"
+
+    env = os.environ.copy()
+    existing = env.get("PYTHONPATH", "")
+    env["PYTHONPATH"] = f"{py_path}:{existing}" if existing else str(py_path)
+    # Ensure conda libs (glfw, imgui, OpenGL) are ahead of system paths.
+    conda_prefix = env.get("CONDA_PREFIX")
+    if conda_prefix:
+        ld_paths = env.get("LD_LIBRARY_PATH", "")
+        env["LD_LIBRARY_PATH"] = (
+            f"{conda_prefix}/lib:{ld_paths}" if ld_paths else f"{conda_prefix}/lib"
+        )
+        preload = env.get("LD_PRELOAD", "")
+        glfw_lib = f"{conda_prefix}/lib/libglfw.so"
+        env["LD_PRELOAD"] = f"{glfw_lib}:{preload}" if preload else glfw_lib
+
+    cmd = [sys.executable, str(script), *remaining]
+    return subprocess.call(cmd, env=env, cwd=repo_root)
 
 
 if __name__ == "__main__":
-  raise SystemExit(main(sys.argv[1:]))
+    raise SystemExit(main(sys.argv[1:]))