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orbingol / NURBS-Python

Object-oriented pure Python B-Spline and NURBS library
https://onurraufbingol.com/NURBS-Python/
MIT License
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Help wanted: unknown ZeroDivisionError #168

Open chenboshuo opened 11 months ago

chenboshuo commented 11 months ago

this is my code

from geomdl import BSpline

# Create a BSpline surface instance (Bezier surface)
surf = BSpline.Surface()

surf.degree_u=2
surf.degree_v=2
surf.ctrlpts_size_u=5
surf.ctrlpts_size_v=9
surf.ctrlpts=[
                (52.5, 60, 0),
                (52.5, 60, 60),
                (52.5, 0, 60),
                (52.5, -59.999999999999986, 60.000000000000007),
                (52.5, -60, 0),
                (52.5, -60.000000000000007, -59.999999999999986),
                (52.5, 0, -60),
                (52.5, 60, -60.000000000000021),
                (52.5, 60, 0),
                (17.500000000000004, 59.999999999999986, 0),
                (17.5, 59.999999999999986, 59.999999999999986),
                (17.500000000000004, 0, 59.999999999999986),
                (17.5, -59.999999999999979, 59.999999999999993),
                (17.500000000000004, -59.999999999999986, 0),
                (17.5, -59.999999999999993, -59.999999999999979),
                (17.500000000000004, 0, -59.999999999999986),
                (17.5, 59.999999999999986, -60),
                (17.500000000000004, 59.999999999999986, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
]
surf.weights=[
1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 0.5, 0.707107, 0.5, 0.707107, 0.5, 0.707107, 0.5, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 6.95192e-310, 52.5, 60, 0, 52.5, 60, 60, 52.5, 3.67e-15, 60, 52.5, -60, 60, 52.5, -60, 7.35e-15, 52.5, -60, ]
surf.knotvector_u=[0, 0, 0, 1, 1, 1, 1, 1, ]
surf.knotvector_v=[0, 0, 0, 0.25, 0.25, 0.5, 0.5, 0.75, 0.75, 1, 1, 1, ]
# Evaluate surface points
surf.evaluate()

and I get below error

ZeroDivisionError                         Traceback (most recent call last)
Input In [83], in <cell line: 1>()
     60 surf.knotvector_v=[0, 0, 0, 0.25, 0.25, 0.5, 0.5, 0.75, 0.75, 1, 1, 1, ]
     61 # Evaluate surface points
---> 62 surf.evaluate()
     64 # Plot the control points grid and the evaluated surface
     65 surf.vis = VisMPL.VisSurface(vis_config)

File ~/anaconda3/lib/python3.9/site-packages/geomdl/BSpline.py:616, in Surface.evaluate(self, **kwargs)
    613 self.reset(evalpts=True)
    615 # Evaluate and cache
--> 616 self._eval_points = self._evaluator.evaluate(self.data,
    617                                              start=(start_u, start_v),
    618                                              stop=(stop_u, stop_v))

File ~/anaconda3/lib/python3.9/site-packages/geomdl/evaluators.py:291, in SurfaceEvaluator.evaluate(self, datadict, **kwargs)
    289     knots = linalg.linspace(start[idx], stop[idx], sample_size[idx], decimals=precision)
    290     spans[idx] = helpers.find_spans(degree[idx], knotvector[idx], size[idx], knots, self._span_func)
--> 291     basis[idx] = helpers.basis_functions(degree[idx], knotvector[idx], spans[idx], knots)
    293 eval_points = []
    294 for i in range(len(spans[0])):

File ~/anaconda3/lib/python3.9/site-packages/geomdl/helpers.py:250, in basis_functions(degree, knot_vector, spans, knots)
    248 basis = []
    249 for span, knot in zip(spans, knots):
--> 250     basis.append(basis_function(degree, knot_vector, span, knot))
    251 return basis

File ~/anaconda3/lib/python3.9/site-packages/geomdl/helpers.py:167, in basis_function(degree, knot_vector, span, knot)
    165 saved = 0.0
    166 for r in range(0, j):
--> 167     temp = N[r] / (right[r + 1] + left[j - r])
    168     N[r] = saved + right[r + 1] * temp
    169     saved = left[j - r] * temp

ZeroDivisionError: float division by zero

The equivalent ACIS code

// spline
    int degree_of_u = 2;
    logical is_rational_in_u = TRUE;
    int OPEN = 0;
    int form_u = OPEN;
    int NO_SINGULARITY_AT_U_BOUNDARY = 0;
    int pole_u = NO_SINGULARITY_AT_U_BOUNDARY;
    int control_points_in_u = 5;
    int degree_v = 2;
    logical is_rational_in_v = TRUE;
    int form_v = 2;
    int pole_v = NO_SINGULARITY_AT_U_BOUNDARY;
    int control_points_in_v = 9;
    SPAposition control_points[] = {
      {52.50000000000000000, 60.00000000000000000,  0.00000000000000000  },
      {52.50000000000000000, 60.00000000000000000,  60.00000000000000000 },
      {52.50000000000000000, 0.00000000000000367,   60.00000000000000000 },
      {52.50000000000000000, -59.99999999999998579, 60.00000000000000711 },
      {52.50000000000000000, -60.00000000000000000, 0.00000000000000735  },
      {52.50000000000000000, -60.00000000000000711, -59.99999999999998579},
      {52.50000000000000000, -0.00000000000001102,  -60.00000000000000000},
      {52.50000000000000000, 60.00000000000000000,  -60.00000000000002132},
      {52.50000000000000000, 60.00000000000000000,  0.00000000000000000  },
      {17.50000000000000355, 59.99999999999998579,  0.00000000000000000  },
      {17.50000000000000000, 59.99999999999998579,  59.99999999999998579 },
      {17.50000000000000355, 0.00000000000000367,   59.99999999999998579 },
      {17.50000000000000000, -59.99999999999997868, 59.99999999999999289 },
      {17.50000000000000355, -59.99999999999998579, 0.00000000000000735  },
      {17.50000000000000000, -59.99999999999999289, -59.99999999999997868},
      {17.50000000000000355, -0.00000000000001102,  -59.99999999999998579},
      {17.50000000000000000, 59.99999999999998579,  -60.00000000000000000},
      {17.50000000000000355, 59.99999999999998579,  0.00000000000000000  },
      {17.50000000000000000, 0.00000000000000000,   0.00000000000000000  },
      {17.50000000000000000, 0.00000000000000000,   0.00000000000000000  },
      {17.50000000000000000, 0.00000000000000000,   0.00000000000000000  },
      {17.50000000000000000, 0.00000000000000000,   0.00000000000000000  },
      {17.50000000000000000, 0.00000000000000000,   0.00000000000000000  },
      {17.50000000000000000, 0.00000000000000000,   0.00000000000000000  },
      {17.50000000000000000, 0.00000000000000000,   0.00000000000000000  },
      {17.50000000000000000, 0.00000000000000000,   0.00000000000000000  },
      {17.50000000000000000, 0.00000000000000000,   0.00000000000000000  },
    };
    double weights[] = {
      1.00000000000000000, 0.70710678118654757, 1.00000000000000000, 0.70710678118654757, 1.00000000000000000, 0.70710678118654757, 1.00000000000000000, 0.70710678118654757, 1.00000000000000000,
      0.70710678118654779, 0.50000000000000022, 0.70710678118654779, 0.50000000000000022, 0.70710678118654779, 0.50000000000000022, 0.70710678118654779, 0.50000000000000022, 0.70710678118654779,
      1.00000000000000000, 0.70710678118654757, 1.00000000000000000, 0.70710678118654757, 1.00000000000000000, 0.70710678118654757, 1.00000000000000000, 0.70710678118654757, 1.00000000000000000,
    };
    double control_points_tolerance = SPAresabs;
    int num_knots_u = 6;
    double knots_u[] = {
      0.00000000000000000, 0.00000000000000000, 0.00000000000000000, 1.00000000000000000, 1.00000000000000000, 1.00000000000000000,
    };
    int num_knots_v = 12;
    double knots_v[] = {
      0.00000000000000000, 0.00000000000000000, 0.00000000000000000, 0.25000000000000000, 0.25000000000000000, 0.50000000000000000,
      0.50000000000000000, 0.75000000000000000, 0.75000000000000000, 1.00000000000000000, 1.00000000000000000, 1.00000000000000000,
    };
    double knot_tol = SPAresabs;
    //
    bs3_surface bezier_surface = bs3_surface_from_ctrlpts(degree_of_u, is_rational_in_u, form_u, pole_u, control_points_in_u, degree_v, is_rational_in_v, form_v, pole_v, control_points_in_v, control_points, weights, control_points_tolerance, num_knots_u,
                                                          knots_u, num_knots_v, knots_v, knot_tol);
    spline spl = spline(bezier_surface);

Could you please take a look at this bug ? I would greatly appreciate your assistance. Thank you in advance!

orbingol commented 11 months ago

I don't have a valid ACIS license anymore, so I cannot test it. ZeroDivisionError may happen, because the algorithms are using the user input directly. There is a frange implementation, but I doubt that's the problem. There were several other problems like that and converting values like -59.99999999999998579 to -60 worked fine at that point. You could try that.

I was planning to implement a more precise floating point control to eliminate such issues, but never had time to do it without adding any additional dependencies.

chenboshuo commented 11 months ago

I don't have a valid ACIS license anymore, so I cannot test it. ZeroDivisionError may happen, because the algorithms are using the user input directly. There is a frange implementation, but I doubt that's the problem. There were several other problems like that and converting values like -59.99999999999998579 to -60 worked fine at that point. You could try that.

I was planning to implement a more precise floating point control to eliminate such issues, but never had time to do it without adding any additional dependencies.

I changed this snippets to

from geomdl import BSpline

# Create a BSpline surface instance (Bezier surface)
surf = BSpline.Surface()

surf.degree_u=2
surf.degree_v=2
surf.ctrlpts_size_u=5
surf.ctrlpts_size_v=9
surf.ctrlpts=[
                (52.5, 60, 0),
                (52.5, 60, 60),
                (52.5, 0, 60),
                (52.5, -60, 60.0),
                (52.5, -60, 0),
                (52.5, -60.0, -60),
                (52.5, 0, -60),
                (52.5, 60, -60.0),
                (52.5, 60, 0),
                (17.5, 60, 0),
                (17.5, 60, 60),
                (17.5, 0, 60),
                (17.5, -60, 60),
                (17.5, -60, 0),
                (17.5, -60, -60),
                (17.5, 0, -60),
                (17.5, 60, -60),
                (17.5, 60, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (17.5, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
                (0, 0, 0),
]
surf.weights=[
1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 0.5, 0.707107, 0.5, 0.707107, 0.5, 0.707107, 0.5, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0, 52.5, 60, 0, 52.5, 60, 60, 52.5, 0, 60, 52.5, -60, 60, 52.5, -60, 0, 52.5, -60, ]
surf.knotvector_u=[0, 0, 0, 1, 1, 1, 1, 1, ]
surf.knotvector_v=[0, 0, 0, 0.25, 0.25, 0.5, 0.5, 0.75, 0.75, 1, 1, 1, ]
# Evaluate surface points
surf.evaluate()

# Plot the control points grid and the evaluated surface
surf.vis = VisMPL.VisSurface(vis_config)

I am still encountering the same error.

orbingol commented 11 months ago

Could you also update the weights like you did for the control points? I'd try converting 0.707107 to 0.70711 and remove one significant if it doesn't work.