Hi FME Community,
I'm trying to create an arc from two Points and a radius:
The radius can be concave or convex depending on the radius sign (negative or positive)
Anyone got any ideas how that can be done using FME?
Thanks in advance
+19- Contributor
Hi, the FMEArc class from Python FME Objects API has a constructor which creates an Arc instance from two points, radius and whether to create counter-clockwise. See the API document.
init(twoPoints, radius, counterClockwise)
Creates an arc using the 2 points contained in the tuple, and the supplied ‘radius’ and points. startPoint and endPoint (twoPoints[0] and twoPoints[1]) must not be None.
Parameters:
twoPoints (tuple[FMEPoint]) – The tuple containing 2 points to create the arc in the form (startPoint, endPoint).
radius (float) – The radius value for the arc to be created.
counterClockwise (bool) – Whether to create a counter-clockwise arc.
A PythonCaller with this script might help you.
import fmeobjects
def createArc(feature):
x1 = float(feature.getAttribute('X1'))
y1 = float(feature.getAttribute('Y1'))
x2 = float(feature.getAttribute('X2'))
y2 = float(feature.getAttribute('Y2'))
twoPoints = (fmeobjects.FMEPoint(x1, y1), fmeobjects.FMEPoint(x2, y2))
radius = float(feature.getAttribute('Radius'))
feature.setGeometry(fmeobjects.FMEArc(twoPoints, abs(radius), 0 < radius))
takashi wrote:
Hi, the FMEArc class from Python FME Objects API has a constructor which creates an Arc instance from two points, radius and whether to create counter-clockwise. See the API document.
init(twoPoints, radius, counterClockwise)
Creates an arc using the 2 points contained in the tuple, and the supplied ‘radius’ and points. startPoint and endPoint (twoPoints[0] and twoPoints[1]) must not be None.
Parameters:
twoPoints (tuple[FMEPoint]) – The tuple containing 2 points to create the arc in the form (startPoint, endPoint).
radius (float) – The radius value for the arc to be created.
counterClockwise (bool) – Whether to create a counter-clockwise arc.
A PythonCaller with this script might help you.
import fmeobjects
def createArc(feature):
x1 = float(feature.getAttribute('X1'))
y1 = float(feature.getAttribute('Y1'))
x2 = float(feature.getAttribute('X2'))
y2 = float(feature.getAttribute('Y2'))
twoPoints = (fmeobjects.FMEPoint(x1, y1), fmeobjects.FMEPoint(x2, y2))
radius = float(feature.getAttribute('Radius'))
feature.setGeometry(fmeobjects.FMEArc(twoPoints, abs(radius), 0 < radius))
Hi, and thanks @takashi
Will that work if radius is set to large number as 3000?
+19- Contributor
takashi wrote:
Hi, the FMEArc class from Python FME Objects API has a constructor which creates an Arc instance from two points, radius and whether to create counter-clockwise. See the API document.
init(twoPoints, radius, counterClockwise)
Creates an arc using the 2 points contained in the tuple, and the supplied ‘radius’ and points. startPoint and endPoint (twoPoints[0] and twoPoints[1]) must not be None.
Parameters:
twoPoints (tuple[FMEPoint]) – The tuple containing 2 points to create the arc in the form (startPoint, endPoint).
radius (float) – The radius value for the arc to be created.
counterClockwise (bool) – Whether to create a counter-clockwise arc.
A PythonCaller with this script might help you.
import fmeobjects
def createArc(feature):
x1 = float(feature.getAttribute('X1'))
y1 = float(feature.getAttribute('Y1'))
x2 = float(feature.getAttribute('X2'))
y2 = float(feature.getAttribute('Y2'))
twoPoints = (fmeobjects.FMEPoint(x1, y1), fmeobjects.FMEPoint(x2, y2))
radius = float(feature.getAttribute('Radius'))
feature.setGeometry(fmeobjects.FMEArc(twoPoints, abs(radius), 0 < radius))
No problem for large radius.
It doesn't work only when the absolute value of radius is less than half of the distance between two points.
Got a reply from one of my collegues (thanks Daniel Kroon) which gives a very good result:
import fme
import fmeobjects
import math
def processFeature(feature):
"""Set the geometry of the feature, either as arc or line, depending on specified Radius.
Expects the following feature attributes to be present: 'X1','Y1','X2','Y2','Radius'
Zero radius creates and sets a line-geometry
Positive radius creates a counter-clockwise arc-geometry.
Negative radius creates a clockwise arc-geometry.
Feature attribute _used_arc_radius contains the actual radius being used when creating the geometry.
"""
# Get coordinates and radius from feature attributes
coords = tuple(map(lambda c: float(feature.getAttribute(c)), ['X1','Y1','X2','Y2']))
radius = float(feature.getAttribute('Radius'))
# Create an arc if radius is other than 0, else create a straight line
if(abs(radius)):
# Create point geometry
twoPoints = tuple(map(lambda c: fmeobjects.FMEPoint(*c), zip(coords[::2],coords[1::2])))
# Calculate the minimul allowed radius for an arc given two points
min_allowed_radius = round(math.sqrt((coords[0]-coords[2])**2+(coords[1]-coords[3])**2)/2,0)
# Create and set arc geometery
use_arc_radius = max(abs(radius),min_allowed_radius)
feature.setGeometry(fmeobjects.FMEArc(twoPoints, use_arc_radius, 0 > radius))
feature.setAttribute('_used_arc_radius',use_arc_radius)
else:
# Create and set arc geometery
feature.setGeometry(fmeobjects.FMELine(list(zip(coords[::2],coords[1::2]))))
feature.setAttribute('_used_arc_radius',0)
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