OpenEuphoria

Re: Gradient Background??

• Posted by Brian Broker <bkb at CNW.COM> Dec 10, 2000
• 565 views

On Sun, 10 Dec 2000 12:51:55 -0500, Brian wrote:

>I'm having a hard time creating a gradient background. I want it to fill in
>the background from black at top to a dark blue at the bottom. I keep
>getting a "Trying to redefine intY" error. Here's the code I'm using.
>
>procedure gradientbg()
>    atom intY
>    sequence gradcolor
>    for intY = 1 to 480 by 1
>    gradcolor = {0, 0, floor(intY / 480) * 255}
>    draw_line(gradcolor, {{1, intY},{640, intY}})
>    next
>    end for
>End Procedure
>
>Any ideas why this is happening?
>
>Draw line repeated 480 times seems a little inefficient. Any ideas on a
>better way of doing this?

I'm hoping that you are not actually running the above code.

  - As David mentioned, you don't need to declare loop variables
  - you don't need to specify "by 1" in your loop, that is the default
  - you are missing a "do" in your "for"
  - there is no "next" in Euphoria
  - in DOS, you have to work with the DOS palette to set your colors

Here is a working demo:
------------------------
include graphics.e
include get.e

-- set graphics mode (missing error message)
if graphics_mode( 257 ) then
  abort(1)
end if

procedure gradientbg()
  sequence gradcolor

  for i = 0 to 63 do
    -- use palette range 192 (black) to 255 (blue)
    gradcolor = palette( i+192, {0, 0, i} )
    for j = 1 to 8 do
      draw_line( i+192, {{0, i*8+j},{639, i*8+j}})
    end for
  end for
end procedure

gradientbg()
-- wait for user to end program, look at pretty gradient
if wait_key() then
  abort(0)
end if

-- restore graphics mode (missing error message)
if graphics_mode(-1) then
  abort(1)
end if

-- good luck,
--  Brian