cape.step: Python interface to STEP Files¶
This module provides an interface to import points, curves, and potentially
other entities in the future from STEP files following ISO 10303-21. It
provides the class cape.step.STEP, which allows the user to read
(preferably simple) STEP files. Its primary purpose is to read STEP files and
write Plot3D curve files.
See also:
pc_Step2Crv
pc_StepTri2Crv
- class cape.step.STEP(fname=None, xtol=None, ytol=None, ztol=None)¶
Interface for STEP files
- Call:
>>> stp = STEP(fname)
- Inputs:
- fname:
str Name of STEP file to read (
.stpor.step)
- fname:
- Outputs:
- stp:
cape.step.STEP STEP file interface
- stp.npt:
int Number of points defined in file
- stp.ncrv:
int Number of curves
- stp.pts:
np.ndarray(float) shape=(npt,3) Array of coordinates of all points defined in file
- stp.ipt:
np.ndarray(int) shape=(npt,) Array of point entity indices; pts[i] is entity pts[ipt[i]]
- stp.crvs:
list(np.ndarray|None) List of sampled curves; initialized to
None- stp.ocrv:
list(int) Order of each spline
- stp.icrv:
list(np.ndarray(int)) Array of indices of knots for each spline
- stp:
- Versions:
2016-05-10
@ddalle: First version
- EvaluateCurve(j, u)¶
Evaluate B-spline of curve j
- Call:
>>> Y = stp.EvaluateCurve(j, u)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- j:
int Curve number
- u:
np.ndarray(float) Values of input parameter to
splev(); like arc length
- stp:
- Outputs:
- Y:
np.ndarray(float) shape=(u.size,3) Points along the spline
- Y:
- Versions:
2016-05-10
@ddalle: First version
- GetCurveKnots(j)¶
Get knots of curve j
- Call:
>>> X = stp.GetCurveKnots(j)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- j:
int Curve number
- stp:
- Outputs:
- X:
np.ndarray(float) shape=(ncrvj,3) Matrix of x, y, and z coordinates of curve j
- X:
- Versions:
2016-05-10
@ddalle: First version
- GetTurningAngle(j)¶
Calculate turning angles between each segment of sampled curve j
- Call:
>>> theta = stp.GetTurningAngle(j)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- j:
int Curve number
- stp:
- Outputs:
- theta:
np.ndarray(float) Angle between each pair of segments in degrees
- theta:
- Versions:
2016-05-10
@ddalle: First version
- GetWeightedTurningAngle(j)¶
Calculate turning angles between each segment of sampled curve j
The turning angle is weighted by the sum of the lengths of the neighboring segments
- Call:
>>> a = stp.GetWeightedTurningAngle(j)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- j:
int Curve number
- stp:
- Outputs:
- a:
np.ndarray(float) Length-weighted angle for each pair (in degree-inches)
- a:
- Versions:
2016-05-10
@ddalle: First version
- LinkCurves(axis='x', ds=1.0)¶
Reorder curves into a single chain
This also ensures that the end of curve j is the start of j+1.
- Call:
>>> stp.LinkCurves(axis='x', ds=1.0)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- axis: {
x} |y|z|-x|-y|-z Dominant sorting axis
- ds:
None|float Maximum gap to close between start and end points
- stp:
- Versions:
2016-05-10
@ddalle: First version
- Read(fname)¶
Read a STEP file
- Call:
>>> stp.Read(fname)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- fname:
str Name of file to read
- stp:
- Versions:
2016-05-10
@ddalle: First version
- SampleCurve(j, n=None, ds=None, dth=None, da=None)¶
Evaluate a B-spline with uniformly distributed points
- Call:
>>> y = stp.SampleCurve(j, n=None, ds=None, dth=None)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- j:
int Curve number
- n:
int (Minimum) number of intervals to use
- ds:
float Upper bound of uniform spacing
- dth:
float| {None} Maximum allowed turning angle in degrees
- da:
float| {None} Maximum allowed length-weighted turning angle
- stp:
- Outputs:
- y
np.ndarray(float) shape=(n,3) Uniformly spaced points along the spline
- y
- Versions:
2016-05-10
@ddalle: First version
- SampleCurves(J=None, n=None, ds=None, dth=None, da=None)¶
Evaluate a list of B-splines with uniformly distributed points
- Call:
>>> stp.SampleCurves(J=None, n=None, ds=None, dth=None, da=None)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- J: {
None} |int List of curve numbers (defaults to all curves)
- n:
int Number of intervals to use
- ds:
float Upper bound of uniform spacing
- dth:
float| {None} Maximum allowed turning angle in degrees
- da:
float| {None} Maximum allowed length-weighted turning angle
- stp:
- Versions:
2016-05-10
@ddalle: First version
- WritePlot3DCurves(fname, J=None, bin=False, endian=None)¶
Write list of curves to Plot3D format
- Call:
>>> stp.WritePlot3DCurves(fname, J=None)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- fname:
str Name of Plot3D file to create
- J: {
None} |list(int) List of curve indices to write (default is all)
- stp:
- Versions:
2016-05-10
@ddalle: First version
- WritePlot3DCurvesASCII(fname, J=None)¶
Write list of curves to ASCII Plot3D format
- Call:
>>> stp.WritePlot3DCurvesASCII(fname, J=None)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- fname:
str Name of Plot3D file to create
- J: {
None} |list(int) List of curve indices to write (default is all)
- stp:
- Versions:
2016-05-10
@ddalle: First version
- WritePlot3DCurvesBin(fname, J=None, **kw)¶
Write list of curves to ASCII Plot3D format
- Call:
>>> stp.WritePlot3DCurvesBin(fname, J=None, endian=None, **kw)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- fname:
str Name of Plot3D file to create
- J: {
None} |list(int) List of curve indices to write (default is all)
- endian: {
None} |"big"|"little" Byte order; use system default if not specified
- single:
True| {False} Whether or not to write single-precision
- stp:
- Versions:
2016-05-10
@ddalle: First version
- WritePlot3DCurves_lr4(fname, J)¶
Write list of curves to single-precision little-endian file
- Call:
>>> stp.WritePlot3DCurves_lr4(fname)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- fname:
str Name of Plot3D file to create
- J: {
None} |list(int) List of curve indices to write (default is all)
- stp:
- Versions:
2016-09-29
@ddalle: First version
- WritePlot3DCurves_lr8(fname, J)¶
Write list of curves to single-precision little-endian file
- Call:
>>> stp.WritePlot3DCurves_lr4(fname)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- fname:
str Name of Plot3D file to create
- J: {
None} |list(int) List of curve indices to write (default is all)
- stp:
- Versions:
2016-09-29
@ddalle: First version
- WritePlot3DCurves_r4(fname, J)¶
Write list of curves to double-precision big-endian file
- Call:
>>> stp.WritePlot3DCurves_r4(fname)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- fname:
str Name of Plot3D file to create
- J: {
None} |list(int) List of curve indices to write (default is all)
- stp:
- Versions:
2016-09-29
@ddalle: First version
- WritePlot3DCurves_r8(fname, J)¶
Write list of curves to double-precision big-endian file
- Call:
>>> stp.WritePlot3DCurves_r8(fname)
- Inputs:
- stp:
cape.step.STEP STEP file interface
- fname:
str Name of Plot3D file to create
- J: {
None} |list(int) List of curve indices to write (default is all)
- stp:
- Versions:
2016-09-29
@ddalle: First version
