Designing Games with Game Maker - YoYo Games

ection,showback,showborder) With this function you can draw a
healthbar (or any other bar that indicates some value, like e.g. the damage).
The arguments x1, y1, x2 and y2 indicate the total area for the bar. amount
indicates the percentage of the bar that must be filled (must lie between 0 and
100). backcol is the color of the background for the bar. mincol and maxcol
indicate the color when the amount is 0 and 100 respectively. For an amount
in between the color is interpolated. So you can easily make a bar that goes
e.g. from green to red. The direction is the direction in which the bar is drawn.
0 indicates that the bar is anchored at the left, 1 at the right, 2 at the top and
3 at the bottom. Finally showback indicates whether a background box must
be shown and showborder indicated whether the box and bar should have a
black border line.
Most of the above functions use the color and alpha setting that can be changed with following
functions.
draw_set_color(col) Sets the drawing color to be used from now on for
drawing primitives.
draw_set_alpha(alpha) Sets the alpha transparency value to be used from
now on for drawing primitives. Should lie in the range 0-1. 0 is fully
transparent, 1 is fully opaque.
draw_get_color() Returns the drawing color used for drawing primitives.
draw_get_alpha() Returns the alpha value used for drawing primitives.
A whole range of predefined colors is available:
c_aqua
c_black
c_blue
c_dkgray
c_fuchsia
c_gray
c_green
c_lime
c_ltgray
c_maroon