[PD] GEM Shear / angle relationship

[cyrille henry]

Le 01/09/2010 10:37, Ed Kelly a écrit :
> Thanks for unlocking my broken trig head.
>
> This should really be in the documentation. The angle is in radians. Patch
> enclosed...
no, the angle is not in radian.
in fact, shear is a non rotational space distortion, there is no angle...

shear distord 1 direction in relation to the coordinate on a 2nd direction.
As Claude explain, you can calculate an angle from this distortion, based on 2 dimension. The tan object is in radian. that's the only thing in radian.

Cyrille



>
> Best,
> Ed
>
>   Metastudio 3 for Pure Data - Free download at:
> http://sharktracks.co.uk/puredata
>
>
>
> ----- Original Message ----
> From: Claude Heiland-Allen<claudiusmaximus at goto10.org>
> To: Ed Kelly<morph_2016 at yahoo.co.uk>
> Cc: PD List<pd-list at iem.at>
> Sent: Wed, 1 September, 2010 1:09:43
> Subject: Re: [PD] GEM Shear / angle relationship
>
> Hi Ed,
>
> On 31/08/10 15:31, Ed Kelly wrote:
>> Can anyone tell me how to calculate the 'shear' value (when using [shearYX] in
>> Gem) from an angle (degrees or radians, I don't mind)?
>
> This is just a guess, for one direction of shear in 2D space:
>
> shear = tan(angle)  (the angle marked ** in the ascii diagram below)
>
> |   __________
> |**/         /
> | /         /
> |/_________/
>
>
> (because tan(0) = 0, tan(45deg) = 1, tan(90deg) = inf)
>
> Otherwise try drawing triangles and doing some trigonometry
> (in a right-angle triangle:
> sin=opposite/diagonal
> cos=adjacent/diagonal
> tan=opposite/adjacent
> )
>
>
> Claude
> -- http://claudiusmaximus.goto10.org
>
>
>
>
>
>
>
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