[sdiy] Silly vector synth question

[Magnus Danielson]

On 06/02/11 16:55, Tom Wiltshire wrote:
>
> On 6 Feb 2011, at 14:32, Colin f wrote:
>
>>
>>> Nice.
>>> This is using the method Magnus suggested, isn't it?
>>
>> Possibly... I only just saw Magnus' post.
>> Here's the formula I used:
>> http://www.colinfraser.com/vector-pan-formula.gif
>> I filled in the purely linear values for x distance = 0 and y distance = 0
>> The formula shown for D4 can be auto-filled to the rest of the table.
>> Two divides and a subtract is probably easy enough to not bother with the
>> LUT.
>
> Here's the equations I used:
>
> // Do the A-C axis
> $osc_a = round((1-$py) * ((1-$px)*100));
> $osc_c = round($py * ($px*100));
>
> // Do the B-D axis
> $osc_b = round($py * ((1-$px)*100));
> $osc_d = round((1-$py) * ($px*100));

These are the type of equations you get from my formulations if you let
PAN(A,B,X)=A*(1-X)+B*X

However, I distinctly had the actual pan-function to be open since it 
may not be the best pan-function to use. But it's a start at least.

> $px and $py are the position of the joystick, from 0 to 1.
> Note that this puts the four oscillators in the corners, necessitating a 45 degree rotation of the joystick to give the 'diamond'. I think I finally understand why they did that!
>
> Well, it keeps you out of trouble on a Sunday afternoon.

I thought you got yourself into trouble... :)

Cheers,
Magnus