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| AG_BLENDFN(3) | FreeBSD Library Functions Manual | AG_BLENDFN(3) |
NAME
AG_BlendFn —
SYNOPSIS
#include <agar/core.h> #include <agar/gui.h>
DESCRIPTION
TheAG_BlendFn type specifies an arithmetic operation to
use when blending 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 "destination" 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
TheAG_BlendFn type first appeared in Agar 1.3.
| September 27, 2009 | FreeBSD 13.1-RELEASE |
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