imagesetbrush() sets the brush image to be used by all line drawing functions (such as imageline() and imagepolygon()) when drawing with the special colors IMG_COLOR_BRUSHED or IMG_COLOR_STYLEDBRUSHED.
Note: You need not take special action when you are finished with a brush, but if you destroy the brush image, you must not use the IMG_COLOR_BRUSHED or IMG_COLOR_STYLEDBRUSHED colors until you have set a new brush image!
Note: This function was added in PHP 4.0.6