Scripts "Find Arc Length" and "Find Chord Length" are identical
- Thread starter oldfox
- Start date
oldfox
Alibre Super User
Andy, I believe they were in the old WizoScript library. I had copied all of the WS scripts to my own directory. That is what I was using. I can't send you a link but I will include the scripts. There are only 2 differences if you do a "File Compare" on them. I deleted line 29 and then moved the leading newline from now line 29 to the end of line 28. Then FC returns "no differences"
****************************************
# FIND CHORD LENGTH
import math
# get current part
P = CurrentPart()
# get a specific 2D sketch
Sk = P.GetSketch("Sketch<1>")
# look for all arcs in sketch
for Fig in Sk.Figures:
# found an arc
if isinstance(Fig, CircularArc):
StartPt = Fig.StartPoint
EndPt = Fig.EndPoint
CenterPt = Fig.Center
Radius = Fig.Radius
# calculate straight-line distance between start and end points
D = math.sqrt(pow(StartPt[0] - EndPt[0], 2) + pow(StartPt[1] - EndPt[1], 2))
# calculate distance along arc between start and end points
Theta = math.acos(1 - ((D * D) / (2 * Radius * Radius)))
Length = (Radius * Theta)
print Length
print "The first four returns from the script are what the script found for arcs."
print "The
print "\nFor ARC < 180 Degrees, MEASURE tool returns 260.720055 mm. CORRECT"
print "For ARC > 180 Degrees, MEASURE tool returns 1383.138526 mm. CORRECT."
pi = 3.141592654
diameter = 660.4
circumference = diameter * pi
halfCircumference = circumference / 2.0
oneThirdCircumference = circumference / 3.0
twoThirdCircumference = circumference / 3.0 * 2.0
fullArc = twoThirdCircumference
segment = 1383.138526 - halfCircumference
print " Circumference = ", diameter * pi
print " 1/3 Circumcerence = ", oneThirdCircumference
print " 2/3 Circumference = ", twoThirdCircumference
print " 1/2 Circumference = %.6f" % halfCircumference
print " Segment = ", twoThirdCircumference - halfCircumference
print "For ARC > 180 Degrees, after substracting 1/2 of the circumference,"
print " SCRIPT returns ", twoThirdCircumference - halfCircumference
print " MEASURE tool returns 345.784631\n"
print "Full arc by SCRIPT = ", twoThirdCircumference
print "Full arc by MEASURE = ", 1383.138526
print "\nSo, bottom line, it looks like the script returns the correct number for arcs greater than 180 degrees. Albeit with rounding errors."
print "Error = ", twoThirdCircumference - 1383.138526, "mm\n"
print "This also verifies, depending on the user's standards, that the measure tool will be good enough to use."
***********************************************
# FIND ARC LENGTH
import math
# get current part
P = CurrentPart()
# get a specific 2D sketch
Sk = P.GetSketch("Sketch<1>")
# look for all arcs in sketch
for Fig in Sk.Figures:
# found an arc
if isinstance(Fig, CircularArc):
StartPt = Fig.StartPoint
EndPt = Fig.EndPoint
CenterPt = Fig.Center
Radius = Fig.Radius
# calculate straight-line distance between start and end points
D = math.sqrt(pow(StartPt[0] - EndPt[0], 2) + pow(StartPt[1] - EndPt[1], 2))
# calculate distance along arc between start and end points
Theta = math.acos(1 - ((D * D) / (2 * Radius * Radius)))
Length = (Radius * Theta)
print Length
print "The first four returns from the script are what the script found for arcs.\n"
print "For ARC < 180 Degrees, MEASURE tool returns 260.720055 mm. CORRECT"
print "For ARC > 180 Degrees, MEASURE tool returns 1383.138526 mm. CORRECT."
pi = 3.141592654
diameter = 660.4
circumference = diameter * pi
halfCircumference = circumference / 2.0
oneThirdCircumference = circumference / 3.0
twoThirdCircumference = circumference / 3.0 * 2.0
fullArc = twoThirdCircumference
segment = 1383.138526 - halfCircumference
print " Circumference = ", diameter * pi
print " 1/3 Circumcerence = ", oneThirdCircumference
print " 2/3 Circumference = ", twoThirdCircumference
print " 1/2 Circumference = %.6f" % halfCircumference
print " Segment = ", twoThirdCircumference - halfCircumference
print "For ARC > 180 Degrees, after substracting 1/2 of the circumference,"
print " SCRIPT returns ", twoThirdCircumference - halfCircumference
print " MEASURE tool returns 345.784631\n"
print "Full arc by SCRIPT = ", twoThirdCircumference
print "Full arc by MEASURE = ", 1383.138526
print "\nSo, bottom line, it looks like the script returns the correct number for arcs greater than 180 degrees. Albeit with rounding errors."
print "Error = ", twoThirdCircumference - 1383.138526, "mm\n"
print "This also verifies, depending on the user's standards, that the measure tool will be good enough to use."
****************************************
# FIND CHORD LENGTH
import math
# get current part
P = CurrentPart()
# get a specific 2D sketch
Sk = P.GetSketch("Sketch<1>")
# look for all arcs in sketch
for Fig in Sk.Figures:
# found an arc
if isinstance(Fig, CircularArc):
StartPt = Fig.StartPoint
EndPt = Fig.EndPoint
CenterPt = Fig.Center
Radius = Fig.Radius
# calculate straight-line distance between start and end points
D = math.sqrt(pow(StartPt[0] - EndPt[0], 2) + pow(StartPt[1] - EndPt[1], 2))
# calculate distance along arc between start and end points
Theta = math.acos(1 - ((D * D) / (2 * Radius * Radius)))
Length = (Radius * Theta)
print Length
print "The first four returns from the script are what the script found for arcs."
print "The
print "\nFor ARC < 180 Degrees, MEASURE tool returns 260.720055 mm. CORRECT"
print "For ARC > 180 Degrees, MEASURE tool returns 1383.138526 mm. CORRECT."
pi = 3.141592654
diameter = 660.4
circumference = diameter * pi
halfCircumference = circumference / 2.0
oneThirdCircumference = circumference / 3.0
twoThirdCircumference = circumference / 3.0 * 2.0
fullArc = twoThirdCircumference
segment = 1383.138526 - halfCircumference
print " Circumference = ", diameter * pi
print " 1/3 Circumcerence = ", oneThirdCircumference
print " 2/3 Circumference = ", twoThirdCircumference
print " 1/2 Circumference = %.6f" % halfCircumference
print " Segment = ", twoThirdCircumference - halfCircumference
print "For ARC > 180 Degrees, after substracting 1/2 of the circumference,"
print " SCRIPT returns ", twoThirdCircumference - halfCircumference
print " MEASURE tool returns 345.784631\n"
print "Full arc by SCRIPT = ", twoThirdCircumference
print "Full arc by MEASURE = ", 1383.138526
print "\nSo, bottom line, it looks like the script returns the correct number for arcs greater than 180 degrees. Albeit with rounding errors."
print "Error = ", twoThirdCircumference - 1383.138526, "mm\n"
print "This also verifies, depending on the user's standards, that the measure tool will be good enough to use."
***********************************************
# FIND ARC LENGTH
import math
# get current part
P = CurrentPart()
# get a specific 2D sketch
Sk = P.GetSketch("Sketch<1>")
# look for all arcs in sketch
for Fig in Sk.Figures:
# found an arc
if isinstance(Fig, CircularArc):
StartPt = Fig.StartPoint
EndPt = Fig.EndPoint
CenterPt = Fig.Center
Radius = Fig.Radius
# calculate straight-line distance between start and end points
D = math.sqrt(pow(StartPt[0] - EndPt[0], 2) + pow(StartPt[1] - EndPt[1], 2))
# calculate distance along arc between start and end points
Theta = math.acos(1 - ((D * D) / (2 * Radius * Radius)))
Length = (Radius * Theta)
print Length
print "The first four returns from the script are what the script found for arcs.\n"
print "For ARC < 180 Degrees, MEASURE tool returns 260.720055 mm. CORRECT"
print "For ARC > 180 Degrees, MEASURE tool returns 1383.138526 mm. CORRECT."
pi = 3.141592654
diameter = 660.4
circumference = diameter * pi
halfCircumference = circumference / 2.0
oneThirdCircumference = circumference / 3.0
twoThirdCircumference = circumference / 3.0 * 2.0
fullArc = twoThirdCircumference
segment = 1383.138526 - halfCircumference
print " Circumference = ", diameter * pi
print " 1/3 Circumcerence = ", oneThirdCircumference
print " 2/3 Circumference = ", twoThirdCircumference
print " 1/2 Circumference = %.6f" % halfCircumference
print " Segment = ", twoThirdCircumference - halfCircumference
print "For ARC > 180 Degrees, after substracting 1/2 of the circumference,"
print " SCRIPT returns ", twoThirdCircumference - halfCircumference
print " MEASURE tool returns 345.784631\n"
print "Full arc by SCRIPT = ", twoThirdCircumference
print "Full arc by MEASURE = ", 1383.138526
print "\nSo, bottom line, it looks like the script returns the correct number for arcs greater than 180 degrees. Albeit with rounding errors."
print "Error = ", twoThirdCircumference - 1383.138526, "mm\n"
print "This also verifies, depending on the user's standards, that the measure tool will be good enough to use."
oldfox
Alibre Super User
OK. I was needing the length of an arc that I was working on and I remembered that these scripts existed. The math is a little over my head so I didn't really look at them in depth. Later upon closer examination and more reading of the "prints" I discovered that I could just use the measure
tool for what I needed. It did indeed work out for me. So I guess that I have no questions any more. I apologize if I wasted your time.
Do you think that Max may be the author?
tool for what I needed. It did indeed work out for me. So I guess that I have no questions any more. I apologize if I wasted your time.
Do you think that Max may be the author?
Lew_Merrick
Guest
Oldfox -- The Length of an Arc is Ɵ (in Radians the Angular Span of the Arc) X r (the Radius of the Arc). This should not be that hard to implement -- just remember that Radians = Degrees X pi/180.
Also remember that Alibre holds angles internally as Radians anyway - see this article for some background
https://support.alibre.com/support/...46021-working-with-equations-in-alibre-design
https://support.alibre.com/support/...46021-working-with-equations-in-alibre-design
ajayre
Alibre Super User
Alibre Script uses degrees for everything and automatically converts to/from radians.
Andy