# Position a node at right angles relative to a line with Python

Hi there,

I’d like to write a script to set a position of P3 node at right angle to the line defined by P1 and P2 points. With some offset of course.

``````def movePoint(x1, y1, x2, y2, offset):
# please, someone write this code :)
return position

position=movePoint(P1.x, P1.y, P2.x, P2.y, 10)
P3.x=position.x
P3.y=position.y

``````

Thanks,
Michał

This code does it:

``````import math

def movePoint(x1, y1, x2, y2, t, offset):
angle = math.atan2(y2 - y1, x2 - x1)
tx = x1 + (x2 - x1) * t
ty = y1 + (y2 - y1) * t
dx = math.sin(angle) * offset
dy = math.cos(angle) * offset
return NSMakePoint(tx + dx, ty - dy)

position = movePoint(P1.x, P1.y, P2.x, P2.y, 1, 10)
P3.x = position.x
P3.y = position.y
``````

I have added an extra parameter `t` to the function that lets you decide where on the line from `P1` to `P2` you want to offset the new point. Set `t = 0` to offset `P1`, set `t = 1` to offset `P2`, or set `t = 0.5` to offset the point in the middle of `P1` and `P2`. You can also pick any other `t` including below `0` and above `1` for extrapolation.

Use a positive `offset` to move the new point to the right side of the line and a negative `offset` to move it to the left side.

I love you!

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