Ambisonic trajectory or expr problem
Hello,
I really cannot figure out how can I move a point along a circle
trajectory, in ambisonic context.
I don't want to use ambisonic rotate mode feature as it has limited
controls.
So i am trying to use expr object.
Let's forget about z coordinates by now,
and say I want to move point A(x,y) knowing just its x coordinate,
the radium (1) and the center point Origin(0,0) of the circumference
I want to move the point along.
I have been using this 2 formulas, but none of them works for
negative values.

Have someone already did that, or know how to deal with negative
values and circumference formulas on a cartesian plane?
really really thanx in advance
im stuck
tom
Hello again,
this is an update of the problem, to show that the formula works
if I use it for calculating the radium:
thanks
please let me know if you can
tom
patch with point loaded on startup
So, what formulae are you using?
hi tom,
what you really need is to convert your position information into
polar (or spherical) coordinates:
you already went part of the way, you're missing how to get the angle
from x and y
in the attached patch i show the full roundtrip of conversion from
cartesian to polar coordinates:
also have a look at http://mathworld.wolfram.com/PolarCoordinates.html
the icst ambisonic tools mainly work in sperical coordinates, since
this is the native format of the ambisonic domain.
for this reason the ambimonitor can handle both types and
transparently converts between the two.
hth
/*j
thank you jasch
very very much.
Now, all the explanation looks great and clear.
I'm studying it now and try to understand if I can do what I want
into polar coordinates.
Il let you know. By now really really thanx
Martin hi,
the formula I was using is this
x2 + y2 - r2 = 0
where x2/y2/r2 mean at the power of 2 (sorry if I dont talk
mathematically correct)
Well the fact is this:
I wanted to be able to just give values of x from -1 to 1 and obtain
the corresponding values for y along a circle trajectory,
using that formula.
By the way jasch teaches me that I cannot do it unless in polar
coordinates, as with cartesian I get stuck with square roots of
negative values,
so that i can draw on ambimonitor only a half-circle trajectory.
Thank you guys, I let you know if I go through it,
but now it's all more clear.
Regards
tom
On 17 Apr 2008, at 17:59, jasch wrote:
> hi tom,
>
> what you really need is to convert your position information into
> polar (or spherical) coordinates:
> you already went part of the way, you're missing how to get the
> angle from x and y
>
> in the attached patch i show the full roundtrip of conversion from
> cartesian to polar coordinates:
> also have a look at http://mathworld.wolfram.com/PolarCoordinates.html
>
> the icst ambisonic tools mainly work in sperical coordinates, since
> this is the native format of the ambisonic domain.
>
> for this reason the ambimonitor can handle both types and
> transparently converts between the two.
>
> hth
>
> /*j
>
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well, no words to thanks.
tom
On 17 Apr 2008, at 17:59, jasch wrote:
> hi tom,
>
> what you really need is to convert your position information into
> polar (or spherical) coordinates:
> you already went part of the way, you're missing how to get the
> angle from x and y
>
> in the attached patch i show the full roundtrip of conversion from
> cartesian to polar coordinates:
> also have a look at http://mathworld.wolfram.com/PolarCoordinates.html
>
> the icst ambisonic tools mainly work in sperical coordinates, since
> this is the native format of the ambisonic domain.
>
> for this reason the ambimonitor can handle both types and
> transparently converts between the two.
>
> hth
>
> /*j
>
> #P window setfont "Sans Serif" 9.;
> #P window linecount 1;
> #P comment 551 718 14 196617 y;
> #P comment 514 718 14 196617 x;
> #P comment 713 651 112 196617 eq. 2 on the same page;
> #P comment 713 633 112 196617 eq. 1 on the same page;
> #P comment 636 491 147 196617 eq. 4 on the same page:;
> #P flonum 595 510 35 9 0 0 0 3 0 0 0 221 221 221 222 222 222 0 0 0;
> #P newex 595 489 35 196617 atan2;
> #P window linecount 4;
> #P message 679 412 145 196617 ; max launchbrowser http://
> mathworld.wolfram.com/PolarCoordinates.html;
> #P window linecount 1;
> #P comment 678 395 147 196617 eq. 3 on the following page:;
> #P comment 577 602 80 196617 angle in radian;
> #P comment 616 651 84 196617 y = r*cos(theta);
> #P comment 616 635 84 196617 x = r*sin(theta);
> #P comment 520 617 38 196617 radius;
> #P flonum 550 700 35 9 0 0 0 3 0 0 0 221 221 221 222 222 222 0 0 0;
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> #P newex 345 447 143 196617 expr $f1 * (180./3.141593);
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