moving object along circle

[sparx10]

I'm trying to move an object along a circle (orbit), and I did come up withthis:

radius = 100
from math import sqrt
for x in range(-radius,radius):
y = sqrt(radius**2-x**2)
print(x, y)

however it moves faster at the beginning and end of the range (y value changes faster than x value) because the x value is changing at a constant ratebut the y value isn't. I can't think of a way to get something to move smoothly around in a circle though..

 

[Steven D'Aprano]

I'm trying to move an object along a circle (orbit), and I did come up
with this:

radius = 100
from math import sqrt
for x in range(-radius,radius):
y = sqrt(radius**2-x**2)
print(x, y)

however it moves faster at the beginning and end of the range (y value
changes faster than x value) because the x value is changing at a
constant rate but the y value isn't. I can't think of a way to get
something to move smoothly around in a circle though..

Instead of using rectangular (x, y) coordinates directly, use polar
coordinates (r, θ) where r (radius) is the constant radius of your
circle, and θ (theta) smoothly varies between 0 and 360°.

http://www.teacherschoice.com.au/maths_library/coordinates/polar_-_rectangular_conversion.htm



import math
radius = 100
for angle in range(0, 361):
theta = math.radians(angle)
x = radius*math.cos(theta)
y = radius*math.sin(theta)
print(x, y)