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AG_BLENDFN(3)	       FreeBSD Library Functions Manual		 AG_BLENDFN(3)

NAME
     AG_BlendFn	-- agar	pixel blending function

SYNOPSIS
     #include <agar/core.h>
     #include <agar/gui.h>

DESCRIPTION
     The AG_BlendFn type specifies an arithmetic operation to use when blend-
     ing two pixels. The incoming pixel	is referred to as the "source" pixel.
     The target	pixel already in the frame buffer is referred to as the	"des-
     tination" pixel.  AG_BlendFn is defined as:

     typedef enum ag_blend_func	{
	     AG_ALPHA_OVERLAY,		     /*	sA+dA */
	     AG_ALPHA_SRC,		     /*	sA */
	     AG_ALPHA_DST,		     /*	dA */
	     AG_ALPHA_ONE_MINUS_DST,	     /*	1-dA */
	     AG_ALPHA_ONE_MINUS_SRC	     /*	1-sA */
     } AG_BlendFn;

     The blending functions differ in how the weight of	the destination	pixel
     (versus the weight	of the source pixel) is	selected.

     AG_PIXEL_SRC uses the alpha component of the source pixel (sA).  This
     function is what one would	normally use to	implement transparency.

     AG_PIXEL_DST uses the alpha component of the destination pixel (dA),

     AG_PIXEL_OVERLAY uses the sum of the source and alpha components, clamped
     to	255.  Note that	this function may be slower than the others depending
     on	the graphics driver in use.

     AG_PIXEL_ONE_MINUS_SRC and	AG_PIXEL_ONE_MINUS_DST use the value 1 minus
     the source	and destination	alpha component.

SEE ALSO
     AG_Intro(3), AG_Widget(3),	AG_Window(3), glBlendFunc(3)

HISTORY
     The AG_BlendFn type first appeared	in Agar	1.3.

FreeBSD	13.0		      September	27, 2009		  FreeBSD 13.0

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | HISTORY

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