How to enlarge a 2D polygon (conex, nonconvex)

[Shamli]

I am looking for an algorithm that enlarge a 2D polygon.
cheers,

 

[Rafal 'Raf256' Maj]

(e-mail address removed)

I am looking for an algorithm that enlarge a 2D polygon.
cheers,

Is polygon is a set of 2D points, how about multiplying all of them by some
value ?

x *= zoom;
y *= zoom;

 

[Shamli]

yes the polygon is a set of 2D points;
No this will not work. by multiplying we are just moving the polygon.

(e-mail address removed)

I am looking for an algorithm that enlarge a 2D polygon.
cheers,

Is polygon is a set of 2D points, how about multiplying all of them by some
value ?

x *= zoom;
y *= zoom;

 

[Arthur J. O'Dwyer]

[re-arranged for clarity]
Please, please, please don't top-post!

A: Because it's annoying as hell.
Q: Why shouldn't I top-post?

(e-mail address removed)

I am looking for an algorithm that enlarge a 2D polygon.
cheers,

Is polygon is a set of 2D points, how about multiplying all of them by some
value ?

x *= zoom;
y *= zoom;

yes the polygon is a set of 2D points;
No this will not work. by multiplying we are just moving the polygon.

No, you're not. You're scaling it by the constant 'zoom'.
Try it and see. Alternately, you can keep the centroid of
the polygon in the same place by first scaling it, and *then*
translating ("moving") it back to the "right" place by adding
a second constant.

Take this to comp.programming (followups set).

-Arthur

 

[Rafal 'Raf256' Maj]

(e-mail address removed)

yes the polygon is a set of 2D points;
No this will not work. by multiplying we are just moving the polygon.

Wrong,
by multiplaying You *are* zooming (and maybe also moving - is object is not
centered before).

To just move we must add x+= y+=

Hm maybe I can write smale example for You, contact mu on priv (I'm adding
(e-mail address removed) to my whitelist)