---
name: "set_write_alpha_blender"
section: "3alleg4"
platform: "linux"
package: "allegro4-doc"
version: "2:4.4.3.1-5"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/set_write_alpha_blender/3alleg4"
---

# set\_write\_alpha\_blender(3alleg4)

Enables the special alpha-channel editing mode. Allegro game programming library.

## NAME

set\_write\_alpha\_blender - Enables the special alpha-channel editing mode. Allegro game programming library.

## SYNOPSIS

**#include \<allegro.h\>**

**void set\_write\_alpha\_blender();**

## DESCRIPTION

Enables the special alpha-channel editing mode, which is used for drawing  alpha channels over the top of an existing 32-bit RGB sprite, to turn it  into an RGBA format image. After calling this function, you can set the  drawing mode to DRAW\_MODE\_TRANS and then write draw color values (0-255)  onto a 32-bit image. This will leave the color values unchanged, but  alter the alpha to whatever values you are writing. After enabling this  mode you can also use draw\_trans\_sprite() to superimpose an 8-bit alpha  mask over the top of an existing 32-bit sprite.

## SEE ALSO

**set\_alpha\_blender**(3alleg4), **draw\_trans\_sprite**(3alleg4), **drawing\_mode**(3alleg4), **exalpha**(3alleg4), **extrans**(3alleg4)