Migrating from ZenCad 1

When migrating scripts, account for changes in types, materialization, and available geometry operation wrappers. Use this table instead of copying old lazy settings.

ZenCad 2 intentionally does not provide compatibility with zencad.lazy. The former user @lazy decorator has no automatic compatible replacement. New domain operations use @zencad.operation; declarations are described in zencad/operation.py and development documents. Do not mechanically rename decorators.

Geometry patterns and assemblies

The unit=True argument is removed from multitrans, multitransform, sqrmirror, sqrtrans, rotate_array and rotate_array2. Geometry functions operate on shapes and do not create assembly or kinematic objects. With array=True they return separate copies; by default they return their boolean union.

Create an explicit unit to keep separate assembly parts:

from zencad import *
from zencad.assemble import unit

part = box(2).right(5)
copies = rotate_array(4, array=True)(part)
assembly = unit(parts=copies)
body = union(copies)
assert len(copies) == 4
assert abs(float(body.mass()) - 32) < 1e-7

Assemblies depend on geometry; geometry does not depend on assemblies. Pass geometric shapes to transform patterns, then put their copies into an assembly, instead of passing interactive objects or units to the pattern. multitransform is a lowercase factory for MultiTransform; sqrtrans is a synonym for sqrmirror.

Graphs and explicit boundaries

import zencad as z

z.configure(cache_enabled=False)
body = z.box(10)
volume = body.mass()                  # Scalar, not float
moved = body.right(volume / 100)      # retains the dependency
assert isinstance(volume, z.Scalar)
assert abs(float(volume) - 1000) < 1e-7
ocp_shape = moved.native()            # materialize for OCP integration

native() returns a native value, not an older Shape wrapper. Keep the original handle for further ZenCad operations. Point + Point is invalid; Point - Point produces Vector, and Vector + Vector produces Vector. Coordinates .x/.y/.z are Scalar values.

len() and iteration materialize topology collections; indexing, slicing and selectors retain the graph. Indices are not persistent face identities across model edits.

Animation and caching

Managed callbacks cannot add or replace geometry after initial show(). Create objects first, then change placement, color and visibility. preanimate and arbitrary Qt access are outside the managed contract. Details.

Processes of the same user share a cache. Old cache records are disposable, not a compatible format. set_evaluation_mode() is a regular function, not a context manager; the previously proposed eager()/immediate()/evaluation() context managers are removed. Evaluation.

Historical curve operations

Older manuals mention curve.length(), curve.linoff(u, dist), and curve.linoff_point(u, dist): curve length, the parameter after an arc-length offset, and the corresponding point. These methods are not present on the current Curve. Use uniform() or uniform_points() for equally spaced samples; sampling is not a replacement for an arbitrary distance offset.

Use OCP to calculate length and arc-length offsets. curve.native() materializes the curve; OCP returns an ordinary number, not a dependent Scalar. Choose the initial parameter and distance within the finite curve domain, and check IsDone() before reading the result.

import math
from zencad import *
from OCP.GeomAdaptor import GeomAdaptor_Curve
from OCP.GCPnts import GCPnts_AbscissaPoint

curve = circle(5, wire=True).curve()
interval = curve.range()
start, end = float(interval.lower), float(interval.upper)
adaptor = GeomAdaptor_Curve(curve.native(), start, end)
length = GCPnts_AbscissaPoint.Length_s(adaptor, start, end)
solver = GCPnts_AbscissaPoint(adaptor, length / 4, start)
assert solver.IsDone()
parameter = solver.Parameter()
point = curve.point(parameter)
assert abs(length - 10 * math.pi) < 1e-7
assert abs(float(point.x)) < 1e-7
assert abs(float(point.y) - 5) < 1e-7

Historical tube function

The old tube(spine, r) constructed the lateral shell of a circular profile, not a tube with wall thickness. Use pipe_shell([profile], spine, solid=False) for that surface. Position the profile at the spine start, perpendicular to its tangent. The example uses a Z-directed spine and an XY circle.

solid=True constructs a capped solid. For a tube with wall thickness, subtract a smaller-radius sweep as in Sweeps. The old bounds=True and approximation parameters tol, cont, maxdegree, maxsegm have no automatic same-named replacements: pipe_shell returns one shape, not a tuple including boundary edges.

from zencad import *

spine = segment((0, 0, 0), (0, 0, 20))
profile = circle(3, wire=True)
surface = pipe_shell([profile], spine, solid=False)
body = pipe_shell([profile], spine)
assert isinstance(surface, Shell)
assert isinstance(body, Solid)
surface.assert_valid()
body.assert_valid()