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Feature/upstream curve fixes #21

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Merged
dvicini merged 2 commits into from
Jul 31, 2026
Merged

Feature/upstream curve fixes #21

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cb5c162
Fix curve width to radius conversion.
Poupine Jul 31, 2026
5d54129
Support all USD curve types in translator.py.
Poupine Jul 31, 2026
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6 changes: 3 additions & 3 deletions hdmitsuba/curves.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -189,13 +189,13 @@ void HdMitsubaCurves::Sync(HdSceneDelegate* sceneDelegate,
// Pack control points [x, y, z, r] (lazy-evaluating widths based on layout)
if (widths_.size() == points_.size()) {
spec.control_points =
PackControlPoints(points_, [&](size_t i) { return widths_[i]; });
PackControlPoints(points_, [&](size_t i) { return widths_[i] * 0.5f; });
} else if (widths_.size() == 1) {
float r = widths_[0];
float r = widths_[0] * 0.5f;
spec.control_points =
PackControlPoints(points_, [&](size_t /*i*/) { return r; });
} else {
float uniform_radius = CalculateMeanWidth(widths_);
float uniform_radius = CalculateMeanWidth(widths_) * 0.5f;
spec.control_points = PackControlPoints(
points_, [&](size_t /*i*/) { return uniform_radius; });
}
Expand Down
18 changes: 13 additions & 5 deletions usd_mitsuba/translator.py
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Original file line number Diff line number Diff line change
Expand Up @@ -121,19 +121,19 @@ def _convert_curves(
time: Usd.TimeCode = Usd.TimeCode.Default(),
) -> mi.Object:
"""Handles a curves prim and returns the Mitsuba curve object."""
curve_prim = UsdGeom.BasisCurves(prim)
curve_prim = UsdGeom.Curves(prim)
curve_points = np.array(curve_prim.GetPointsAttr().Get(time))
bsdf, _, _ = material.convert_material(prim)
widths = curve_prim.GetWidthsAttr().Get(time)
if widths is not None:
widths = np.array(widths)
if widths.ndim == 0 or widths.size == 1:
radius = np.full((curve_points.shape[0], 1), widths.item())
radius = np.full((curve_points.shape[0], 1), widths.item() * 0.5)
elif widths.size == curve_points.shape[0]:
radius = widths.reshape(-1, 1)
radius = widths.reshape(-1, 1) * 0.5
else:
# Fallback to mean for other interpolations (e.g., uniform per curve)
radius = np.full((curve_points.shape[0], 1), np.mean(widths))
radius = np.full((curve_points.shape[0], 1), np.mean(widths) * 0.5)
else:
radius = np.full((curve_points.shape[0], 1), 0.01)
curve_points = np.hstack([curve_points, radius])
Expand All @@ -143,6 +143,14 @@ def _convert_curves(

# TODO: Correctly parse this from the USD prim.
curve_type = 'linearcurve'
if (
hasattr(curve_prim, 'GetTypeAttr')
and curve_prim.GetTypeAttr().Get(time) == 'cubic'
and curve_prim.GetBasisAttr().Get(time) == 'bspline'
):
curve_type = 'bsplinecurve'
elif prim.IsA(UsdGeom.NurbsCurves):
curve_type = 'bsplinecurve'
curve_obj = _create_empty_mitsuba_curve(curve_type, bsdf)
degree = 3 if curve_type == 'bsplinecurve' else 1
params = mi.traverse(curve_obj)
Expand Down Expand Up @@ -272,6 +280,6 @@ def convert_to_mitsuba(
UsdLux.BoundableLightBase
):
mi_scene_dict[mi_id] = light.convert_light(prim, time)
elif prim.IsA(UsdGeom.BasisCurves):
elif prim.IsA(UsdGeom.Curves):
mi_scene_dict[mi_id] = _convert_curves(prim, time)
return mi_scene_dict
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