Editing r2y - FilterMeisterWiki

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 _   __ _______ ZZ    ZZ   ______   ____  
| | / /(  ____ \ ZZZ ZZZ  |  ____| | __ ) 
| |/ / | (    \/ Z ZZ ZZ  | |__    |  _ \ 
|    \ | |       Z ZZ ZZ  |  __|   | |_) |
| |\  \| |       Z ZZ ZZ  | |____  |____/ 
\_| \_/| |       Z  Z ZZ  |______|        
       | (____/\ZZZ   ZZ                  
       (_______/

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= r2y =
== Syntax ==
:{{int r2y(int d, int m)}}
== Arguments ==
:'''d'''
::An integer value for the 'direction' of a pixel.
:'''m'''
::An integer value for the 'magnitude' of a pixel.
== Return ==
:An integer giving the cartesian y coordinate for the pixel whose polar coordinates are [d,m].
== Description ==
:Pixels are usually addressed by their cartesian coordinates [x,y], but FilterMeister also allows the use of polar coordinates, and provides a set of functions for conversion between the two systems. Polar coordinates are expressed as [d,m], where 'd' represents the 'direction' to the pixel from the image's center point, and 'm' is the 'magnitude' of the distance from the center. The r2y() function takes a pair of polar coordinates as arguments, and returns the cartesian y coordinate of the corresponding pixel.
== Example ==
<code>
%ffp

ForEveryTile:
{

int centerX = 100; // distances from the top left corner of the image
int centerY = 100;

int radius = 50;

int angle = 360;

int thd; // angle in degrees
int thk; // angle from -511 to 512

for (thk=0; thk<=angle; thk++) {

thd = (-thk * 1024)/360;
  if (thd < -511)
    thd += 1024;

for (z=0; z<Z; z++)
    pset(r2x(thd, radius) + centerX, r2y(thd, radius) + centerY, z, 0);
}

return true;

}
</code>
== Also see ==
:((c2d)),((c2m)),((r2x))
== Comments ==
:Everyone can add his comments about his experiences with this function here. Tips for using it are welcome, too.

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