Surface modelling with Mathmod workbench

[seanx]

I created the surface



I also did a linear extrude :




You can see, from the side that the "arches" aren't always symmetric. They should be though. This seems to be an error in the curve itself.


This is the front view. This is correct.


See how clearly you can identify the sin wave at the boundary.

The right or left view looks like this :


The distortion is clearly visible. This si not an artifact of viewing angle. I checked every angle on the rotation disk. Tools (Werkzeuge) -> rotation disk ( Drehscheibe)

Part 3D does not work. It produces ghastly results, no matter how i change my settings and refresh view.

Notice how one surface tares through another.

All settings create the same result.

Thank you

[TheMarkster]

I made a draft clone and scaled it down for an additional support edge towards the center.

Snip macro screenshot-e4157d.png (62.42 KiB) Viewed 1352 times

[seanx]

I made a draft clone and scaled it down for an additional support edge towards the center.

Snip macro screenshot-e4157d.png

Hi
That seems to have worked.

If i use two different curves, the surface screws up. But if I use the draft --> clone option, they are more likely to succeed. I wonder why that is.

My first guess was that they have different length of point array that makes the spline curve. But the array of t-parameter used in both curves are the same. So why such a problem??

Thank you.

[TheMarkster]

I don't think the number of points matters so much. Sometimes more is better, but sometimes fewer is better. Look also at Curves workbench where there are some nice tools. For example you can split the bspline into separate edges and use some of the surface workbench tools. There is also a gordon surface tool there.

[vm4dim]

I found them in the macro installation dialog
But they dont seem to support the handling of surfaces.

I would appreciate a parametric surface creation tool.

For example, I would like to create this surface and give it a thickness.



Thank you.

@seanx
Enneper Surface with thickness

Code: Select all

import FreeCAD as App
import FreeCADGui
import Part

doc = App.newDocument('NewDoc')

width = 8
step = 0.2
thin = 0.02

loft_sect = []

for U in range(-width, width+1, 1):
    pl4a = []
    pl4b = []
    for V in range(-width, width+1, 1):
        u = U * step
        v = V * step
        x = u * (1 - u*u/3 + v*v) / 3
        y = v * (1 - v*v/3 + u*u) / 3
        z = (u*u - v*v) / 3
        b = 6*u
        c = -6*v
        d = -3 * (1 - u*u - v*v)
        r = (b*b + c*c + d*d) **0.5
        pl4a.append(App.Vector(x + thin*b/r, y + thin*c/r, z + thin*d/r))
        pl4b.append(App.Vector(x - thin*b/r, y - thin*c/r, z - thin*d/r))

    pl4b.reverse()
    pl4b.append(pl4a[0])

    p1 = doc.addObject('Part::Feature', 'PLG')
    p1.Shape = Part.makePolygon(pl4a.__add__(pl4b))
    p1.Visibility = False
    loft_sect.append(p1)

loft = doc.addObject('Part::Loft','Loft')
loft.Ruled = True
loft.Sections = loft_sect

doc.addObject('Part::Feature', 'FF1').Shape = Part.makeFilledFace(loft_sect[0].Shape.Edges)
doc.addObject('Part::Feature', 'FF2').Shape = Part.makeFilledFace(loft_sect[-1].Shape.Edges)
doc.addObject('Part::Compound', 'Compound1').Links = [loft, doc.FF1, doc.FF2]

doc.recompute()
Gui.SendMsgToActiveView('ViewFit')

[seanx]

I found them in the macro installation dialog
But they dont seem to support the handling of surfaces.

I would appreciate a parametric surface creation tool.

For example, I would like to create this surface and give it a thickness.



Thank you.

@seanx
Enneper Surface with thickness

Code: Select all

import FreeCAD as App
import FreeCADGui
import Part

doc = App.newDocument('NewDoc')

width = 8
step = 0.2
thin = 0.02

loft_sect = []

for U in range(-width, width+1, 1):
    pl4a = []
    pl4b = []
    for V in range(-width, width+1, 1):
        u = U * step
        v = V * step
        x = u * (1 - u*u/3 + v*v) / 3
        y = v * (1 - v*v/3 + u*u) / 3
        z = (u*u - v*v) / 3
        b = 6*u
        c = -6*v
        d = -3 * (1 - u*u - v*v)
        r = (b*b + c*c + d*d) **0.5
        pl4a.append(App.Vector(x + thin*b/r, y + thin*c/r, z + thin*d/r))
        pl4b.append(App.Vector(x - thin*b/r, y - thin*c/r, z - thin*d/r))

    pl4b.reverse()
    pl4b.append(pl4a[0])

    p1 = doc.addObject('Part::Feature', 'PLG')
    p1.Shape = Part.makePolygon(pl4a.__add__(pl4b))
    p1.Visibility = False
    loft_sect.append(p1)

loft = doc.addObject('Part::Loft','Loft')
loft.Ruled = True
loft.Sections = loft_sect

doc.addObject('Part::Feature', 'FF1').Shape = Part.makeFilledFace(loft_sect[0].Shape.Edges)
doc.addObject('Part::Feature', 'FF2').Shape = Part.makeFilledFace(loft_sect[-1].Shape.Edges)
doc.addObject('Part::Compound', 'Compound1').Links = [loft, doc.FF1, doc.FF2]

doc.recompute()
Gui.SendMsgToActiveView('ViewFit')

This is perfect.
Thank you