Editing c2d - FilterMeisterWiki

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= c2d =
== Syntax ==
:{{int c2d(int x, int y)}}
== Arguments ==
:'''x'''
::An integer pixel x-coordinate.
:'''y'''
::An integer pixel y-coordinate.
== Return ==
:An integer in the range -511 to 512.
== 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 origin [0,0], and 'm' is the 'magnitude' of the distance from the origin. The c2d() function returns the polar coordinate direction 'd' for the pixel at [x,y], relative to the top left corner of the image. A 'd' value of 0 represents the direction to the right along the x-axis (ie y=0); a value of 256 represents the direction downward along the y-axis (ie x=0); a value of 512 represents the direction to the left along the x-axis (where y=0); and a value of -256 represents the upward direction on the y-axis (where x=0). Naturally, intermediate values represent the intermediate angles. 
== Example ==
<code>
%ffp

ForEveryTile:
{

for (y=y_start; y<y_end; ++y)
{
	for (x=x_start; x<x_end; ++x)
	{
		for (z=0; z<Z; ++z)
		{
			pset(x, y, z, (256 * abs(c2d(x-X/2, y-Y/2)))/512);
		}
	}
}

return true;

</code>
== Also see ==
:((c2m)),((r2x)),((r2y))
== Comments ==
:Everyone can add his comments about his experiences with this function here. Tips for using it are welcome, too.

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