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.
Замечание:
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!