construction.SketchPlane
construction.SketchPlane(
origin=(0.0, 0.0, 0.0),
normal=(0.0, 0.0, 1.0),
x_axis=None,
)A work plane the sketch entities live on.
Defines a coordinate frame: origin plus orthonormal in-plane axes (u, v) derived from normal and, optionally, an explicit x_axis. Profile coordinates (x, y) map to world space as origin + x·u + y·v.
Parameters
| Name | Type | Description | Default |
|---|---|---|---|
| origin | Plane origin in world space (Vector parameter or 3D array). | (0.0, 0.0, 0.0) |
|
| normal | Plane normal (Vector parameter or 3D array); default +Z, i.e. the world XY plane. | (0.0, 0.0, 1.0) |
|
| x_axis | Optional in-plane “horizontal”. Its component along the normal is removed, so any direction not parallel to the normal will do. Omit it to keep the normal-only derivation. Orientation is a snapshot — unlike origin it is not a tracked parameter — which mirrors how the generators already capture rotation at generation time. |
None |
Attributes
| Name | Description |
|---|---|
| reference | What this plane was derived from — a Face, an SDF, or None. |
| x_axis | The explicit in-plane horizontal, or None when derived from the normal. |
Methods
| Name | Description |
|---|---|
| axis_angle | Axis-angle form of :meth:rotation_matrix (for the Rotate transform). |
| describe | Serialize the plane’s frame for the viewer. |
| frame | Return the (u, v, n) orthonormal frame as arrays. |
| is_identity | True when the plane is the world XY plane at the origin. |
| midplane | The plane halfway between two faces. |
| offset | A face or plane pushed along its own normal. |
| on | The plane of a face, moving with the feature’s parameters. |
| rotation_matrix | Rotation taking local (x, y, z) to world (u, v, n), columns [u v n]. |
| tangent | The tangent plane of an SDF at the surface point nearest near. |
| to_world | Map plane coordinates (…, 2) to world coordinates (…, 3). |
axis_angle
construction.SketchPlane.axis_angle()Axis-angle form of :meth:rotation_matrix (for the Rotate transform).
Returns
| Name | Type | Description |
|---|---|---|
| tuple[Array, float | Array] | The pair (axis, angle). angle is a Python float whenever the plane’s orientation is concrete — which is what lets :func:cadjoint.construction.extrude._place_on_plane drop an identity rotation entirely — and a traced array otherwise. |
describe
construction.SketchPlane.describe()Serialize the plane’s frame for the viewer.
frame
construction.SketchPlane.frame()Return the (u, v, n) orthonormal frame as arrays.
is_identity
construction.SketchPlane.is_identity()True when the plane is the world XY plane at the origin.
A plane whose origin or orientation is traced answers False: it cannot be proved identical to the world frame, and the placement transforms it then keeps are the identity anyway.
midplane
construction.SketchPlane.midplane(face_a, face_b)The plane halfway between two faces.
Parameters
| Name | Type | Description | Default |
|---|---|---|---|
| face_a | The first face (or plane). | required | |
| face_b | The second face (or plane). | required |
Returns
| Name | Type | Description |
|---|---|---|
| SketchPlane | A plane at the midpoint of the two origins, normal to the average of the two normals. A face pair usually points at each other, so the second normal is flipped into agreement with the first before averaging; that keeps the result well defined for the parallel, antiparallel and general cases alike. |
offset
construction.SketchPlane.offset(reference, distance)A face or plane pushed along its own normal.
Parameters
| Name | Type | Description | Default |
|---|---|---|---|
| reference | A :class:~cadjoint.construction.faces.Face or another :class:SketchPlane. |
required | |
| distance | How far to move along the normal. May be a Scalar parameter, in which case the offset is a design variable like any other. |
required |
Returns
| Name | Type | Description |
|---|---|---|
| SketchPlane | The offset plane, keeping the reference’s orientation. |
on
construction.SketchPlane.on(face, x_axis=None, flip=False)The plane of a face, moving with the feature’s parameters.
Parameters
| Name | Type | Description | Default |
|---|---|---|---|
| face | A :class:~cadjoint.construction.faces.Face — solid.cap("+"), solid.side(2), block.face("+x"). |
required | |
| x_axis | Override the sketch’s in-plane horizontal; defaults to the face’s own x axis (the profile’s u for a cap, the swept edge direction for a side wall). |
None |
|
| flip | bool | Face the plane the other way, keeping the same origin. | False |
Returns
| Name | Type | Description |
|---|---|---|
| SketchPlane | A plane whose origin is an expression in the parent feature’s parameters, so it follows the parent and carries its gradient. |
Example
body = extrude(profile, depth=fin_depth)
boss = PolygonProfile(SQUARE, plane=SketchPlane.on(body.cap("+")))rotation_matrix
construction.SketchPlane.rotation_matrix()Rotation taking local (x, y, z) to world (u, v, n), columns [u v n].
tangent
construction.SketchPlane.tangent(
solid,
near,
x_axis=None,
*,
max_step=1.0,
steps=8,
normal_step=0.001,
)The tangent plane of an SDF at the surface point nearest near.
This is the reference for everything with no analytic face: blends, fillets, the curved wall of a revolve. near is Newton-projected onto the zero set with :func:cadjoint.fem.motion.project_points, and the plane’s normal is read off the field by a central difference across the surface — both differentiable, so the plane tracks the scene’s parameters rather than a snapshot of them. The difference is used in place of jax.grad because the surface is exactly where a CSG field changes branch; see :func:_surface_normal.
Parameters
| Name | Type | Description | Default |
|---|---|---|---|
| solid | Any callable scalar field on (3,) points — an SDF instance is one. |
required | |
| near | A world point at or near the surface; a raymarch hit is the intended source. | required | |
| x_axis | Override the in-plane horizontal; defaults to the world axis most nearly inside the tangent plane. | None |
|
| max_step | float | Cap on how far the projection may move near. |
1.0 |
| steps | int | Newton iterations. | 8 |
| normal_step | float | Half-width of the central difference that reads the normal. Raise it on a field that is noisy at the surface, lower it where two faces meet within a thousandth. | 0.001 |
Returns
| Name | Type | Description |
|---|---|---|
| The tangent plane at the projected point. |
to_world
construction.SketchPlane.to_world(xy)Map plane coordinates (…, 2) to world coordinates (…, 3).