You can get a quick fix though (the code you should look at is in the 'DisableBlueScreen' function) :
sync on
sync rate 0
DisableBlueScreen()
` Create a test image
cls 0xffffff
get image 1,0,0,64,64
` Draw random lines on screen
cls
for i=0 to 999
ink rgb( rnd(256),rnd(256),rnd(256) ),0
line rnd(640),rnd(480),rnd(640),rnd(480)
next i
sprite 1,100,100,1
set sprite 1,1,0
do
sx=sprite x(1)
sy=sprite y(1)
if leftkey()=1 and sx>0 then dec sx,4
if rightkey()=1 and sx<(639-64) then inc sx,4
if upkey()=1 and sy>0 then dec sy,4
if downkey()=1 and sy<(479-64) then inc sy,4
sprite 1,sx,sy,sprite image(1)
sync
loop
function DisableBlueScreen()
get image 65535,0,0,1,1
sprite 655352,-200,-200,65535
set sprite 2,0,0
backdrop off
endfunction
But you will find that the above code runs terribly slow.
My advice is to ensure that backsave is switched off for all your sprites and to redraw the background yourself every frame. That's what this slightly modified code does :
sync on
sync rate 0
DisableBlueScreen()
` Create a test image
cls 0xffffff
get image 1,0,0,64,64
` Draw random lines on screen
cls
for i=0 to 999
ink rgb( rnd(256),rnd(256),rnd(256) ),0
line rnd(640),rnd(480),rnd(640),rnd(480)
next i
` Capture the backdrop without antialiasing
get image 2,0,0,640,480,1
sprite 1,100,100,1
do
paste image 2,0,0,0 : ` draw the backdrop without transparency
sx=sprite x(1)
sy=sprite y(1)
if leftkey()=1 and sx>0 then dec sx,4
if rightkey()=1 and sx<(639-64) then inc sx,4
if upkey()=1 and sy>0 then dec sy,4
if downkey()=1 and sy<(479-64) then inc sy,4
sprite 1,sx,sy,sprite image(1)
sync
loop
function DisableBlueScreen()
get image 65535,0,0,1,1
sprite 655352,-200,-200,65535
set sprite 2,0,1
backdrop off
endfunction
You'll probably note that I haven't switched off the backsave facility on sprite 1 - that's because there seems to be a 'feature' in DBPro that once you switch the first one off, all new sprites are created with the backsave facility off.
Also, I'm still switching the backdrop off, because otherwise the system would waste time clearing the screen to blue, just so that I can overwrite it all with my image - if you have a crap video card like mine (
) this saves quite a bit of time per frame.
