Drawing Parabole, need help [SOLVED]

[Kunstmaan]

Some years ago I created a "Wizo" script to make a parbole and at that time it worked.
But now it doesnt, so I am puzled.

Units.Current = UnitTypes.Millimeters
x_max = 600
y_max = 180
step = 25
f = 500
#formula  x=y^2/4f

def para(x):
    y = x**2 / (4*f)
    print " x = %.3f , y = %.3f" % (x, y)
    return(y)

#Create part
MyPart = Part("Parabola")
Parabola = MyPart.AddSketch("Parabola", MyPart.GetPlane("XY-Plane"))

#Generate list of points
points = []
for x in range(0, x_max+step, step):
    points.extend([x, para(x)])

# Place it in a sketch
Parabola.AddBsplineThroughPoints(3, points, False)

Can somebody what wrong in this code

 

[idslk]

your last line should look:
Parabola.AddBspline(points, False)

in addition to be language independent you should use "MyPart.XYPlane" instead of "MyPart.GetPlane("XY-Plane")"

 

[Kunstmaan]

your last line should look:
Parabola.AddBspline(points, False)

This change creates a error

 

[idslk]

This change creates a error

which one?
Here it runs:

Units.Current = UnitTypes.Millimeters
x_max = 600
y_max = 180
step = 25
f = 500
#formula  x=y^2/4f

def para(x):
    y = x**2 / (4*f)
    print " x = %.3f , y = %.3f" % (x, y)
    return(y)

#Create part
MyPart = Part("Parabola")
Parabola = MyPart.AddSketch("Parabola", MyPart.XYPlane) #GetPlane("XY-Plane"))

#Generate list of points
points = []
for x in range(0, x_max+step, step):
    points.extend([x, para(x)])

# Place it in a sketch
Parabola.AddBspline(points, False)

 

[albie0803]

Works in v27 as well but the curve has a few wobbles in it.

 

[Kunstmaan]

It runs here also after I reentered the two lines Thnks

 

[FailureByDesign]

....may I ask, given the equation for the Parabola, what is the best way to remove the wobbles in the parabolic curve?

 

[stepalibre]

....may I ask, given the equation for the Parabola, what is the best way to remove the wobbles in the parabolic curve?

Is this better?

Units.Current = UnitTypes.Millimeters
x_max = 600
y_max = 180
f = 500
def para(x):
    y = float(x**2) / (4*f)
    print " x = %.3f , y = %.3f" % (x, y)
    return y
MyPart = Part("Parabola")
Parabola = MyPart.AddSketch("Parabola", MyPart.XYPlane)
points = []
x = 0
while x <= 50:
    y = para(x)
    if y <= y_max:
        points.extend([x, y])
    x += 1
while x <= 200:
    y = para(x)
    if y <= y_max:
        points.extend([x, y])
    x += 3
while x <= x_max:
    y = para(x)
    if y <= y_max:
        points.extend([x, y])
    x += 5
Parabola.AddBspline(points, False)

You can increase points to make a smoother curve.

 

[FailureByDesign]

Is this better?
View attachment 43361

Units.Current = UnitTypes.Millimeters
x_max = 600
y_max = 180
f = 500
def para(x):
    y = float(x**2) / (4*f)
    print " x = %.3f , y = %.3f" % (x, y)
    return y
MyPart = Part("Parabola")
Parabola = MyPart.AddSketch("Parabola", MyPart.XYPlane)
points = []
x = 0
while x <= 50:
    y = para(x)
    if y <= y_max:
        points.extend([x, y])
    x += 1
while x <= 200:
    y = para(x)
    if y <= y_max:
        points.extend([x, y])
    x += 3
while x <= x_max:
    y = para(x)
    if y <= y_max:
        points.extend([x, y])
    x += 5
Parabola.AddBspline(points, False)

You can increase points to make a smoother curve.

Thanks Stephen, you're a legend!!!!

LOVE the Alibre community

 

[FailureByDesign]

Thanks Stephen, you're a legend!!!!

LOVE the Alibre community

Oh and apologies for not replying sooner....been super-busy

 

[bolsover]

Just out of curiosity, I wondered what might be done to generate a parabolic curve without using a script - just the equation editor.
For a plain parabola with a 0,0 vertex it turns out to be simple and the curve can be controlled with just 2 parameters.
Would be a little more complex for an offset vertex.

 

[FailureByDesign]

Hi David, Happy New Year! , hmmm, I had not considered that approach (silly me). I will take a look at this method however, I am dealing with optics that requires a unique parabolic shape....I am wondering if your approach could accommodate that....I'll try and get back to you.
Thanks so much for your detailed response.

 

[bolsover]

Hi David, Happy New Year! , hmmm, I had not considered that approach (silly me). I will take a look at this method however, I am dealing with optics that requires a unique parabolic shape....I am wondering if your approach could accommodate that....I'll try and get back to you.
Thanks so much for your detailed response.

@FailureByDesign
After the earlier post, I played with the idea some more..
I adjusted the formulae so you can enter just height and width of the parabola - also calculated focal point..
David

 

[FailureByDesign]

@FailureByDesign
After the earlier post, I played with the idea some more..
I adjusted the formulae so you can enter just height and width of the parabola - also calculated focal point..
David

Hi David, the parabolic shape looks good however, would you be interested in sharing your script? (no problems if you don't).

FBD

 

[bolsover]

Hi David, the parabolic shape looks good however, would you be interested in sharing your script? (no problems if you don't).

FBD

There is no script. Just a couple of parameters in the equation editor. Just width and height IIRC.
David

 

[FailureByDesign]

There is no script. Just a couple of parameters in the equation editor. Just width and height IIRC.
David

Oh, ok, understood.

Thanks David, have a great day.