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.TH "ALLEGRO_SHADER_TYPE" "3alleg5" "" "Allegro reference manual" ""
.hy
.SH NAME
.PP
ALLEGRO_SHADER_TYPE - Allegro 5 API
.SH SYNOPSIS
.IP
.nf
\f[C]
#include <allegro5/allegro.h>

typedef enum ALLEGRO_SHADER_TYPE ALLEGRO_SHADER_TYPE;
\f[R]
.fi
.SH DESCRIPTION
.PP
Used with al_attach_shader_source(3alleg5) and
al_attach_shader_source_file(3alleg5) to specify how to interpret the
attached source.
.TP
ALLEGRO_VERTEX_SHADER
A vertex shader is executed for each vertex it is used with.
The program will output exactly one vertex at a time.
.RS
.PP
When Allegro\[cq]s graphics are being used then in addition to all
vertices of primitives from the primitives addon, each drawn bitmap also
consists of four vertices.
.RE
.TP
ALLEGRO_PIXEL_SHADER
A pixel shader is executed for each pixel it is used with.
The program will output exactly one pixel at a time - either in the
backbuffer or in the current target bitmap.
.RS
.PP
With Allegro\[cq]s builtin graphics this means the shader is for example
called for each destination pixel of the output of an
al_draw_bitmap(3alleg5) call.
.PP
A more accurate term for pixel shader would be fragment shader since one
final pixel in the target bitmap is not necessarily composed of only a
single output but of multiple fragments (for example when multi-sampling
is being used).
.RE
.SH SINCE
.PP
5.1.0