[EDIT]

Hello !

After 3-4 days of search, I have found a very good solution for make physics body from a sprite.

The solution of @Ignatz is interesting but for make bigger simulation, that is not enough.

I share my code when my class was clean.

[EDIT]

Hello !

After 3-4 days of search, I have found a very good solution for make physics body from a sprite.

The solution of @Ignatz is interesting but for make bigger simulation, that is not enough.

I share my code when my class was clean.

Are you trying to find the angle of a vector? If so use this function:

```
function angleOfPoint( pt )
local x, y = pt.x, pt.y
local radian = math.atan2(y,x)
local angle = radian*180/math.pi
if angle < 0 then angle = 360 + angle end
return angle
end
```

Excuse me, my word is bad. I have rename angle by corner.

I have a array of points that describes contours of a polygon, and I try to find corner in this array.

Simple example:

```
XXXXXXXXXXX
X X
X X
XXXXXXXXXXX
I want found O :
OXXXXXXXXXO
X X
X X
OXXXXXXXXXO
```

For the moment, I have not found a algorithm to resolve my problem.

So, I use algorithm of Radius Simplify to reduce number of points in my array, but it’s not enough.

I have try algorithm of DouglasPeucker (for the same goal) but my version doesn’t work.

— Comment deleted

@HyroVitalyProtago Have you looked at the code by @Ignatz to generate a physics body from a sprite image? http://twolivesleft.com/Codea/Talk/discussion/2297/utility%3A-create-a-physics-object-that-follows-the-exact-outline-of-your-image

Thanks a lot @Simeon.

Hmmh, Algorithm of @Ignatz is interesting but not enough for me…

My algorithm is slower than his, but my solution is more efficient and that could be better if I find how found corner in array of points.

```
Exemples :
His solution for "Tyrian Remastered:Blimp Boss" : 57 points
My solution : 33 points
Future solution not interesting for this case.
His solution for "Space Art:Asteroid Large" : 62 points
My solution : 39 points
My "future" solution : ~8 points
```

@Simeon, @Ignatz, if you have any idea

With DouglasPeucker :

```
"Tyrian Remastered:Blimp Boss" : 28 (~31 (if you want more precision) )
"Space Art:Asteroid Large" : 14
My "future" solution : ~8 points
```

Combinaison of RadiusSimplify & DouglasPeucker =>The Best Solution !!!

```
"Tyrian Remastered:Blimp Boss" : 20
"Space Art:Asteroid Large" : 9
```