Getting a flicker when I use Screen data

[Brian's Man Cave]

Hey,

 

I am using the tecnique from the game Monkey Moon in the Programming for Intellivision book. I set up my const variables and write them to the screen using data to make my playfield.

 

problem is that when I add anything using the Backtab command or Print command, it shows up flickering.

 

Is there somthing I am missing?

 

 

const oo = 0
const gb = $0804 + 1 * 8 'green bush
const rb = $0802 + 1 * 8 'red bush
const ex = $0803 + 3 * 8 'exit room

 

screen room_1

print at 0 color 2, <>lives

 

room_1:
data oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo
data oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo
data oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo
data oo,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,oo
data oo,gb,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,ex,oo
data oo,gb,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,ex,oo
data oo,gb,oo,rb,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,ex,oo
data oo,gb,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,gb,oo
data oo,gb,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,gb,oo
data oo,gb,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,gb,oo
data oo,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,oo
data oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo

[+DZ-Jay]

Could you show your full code?  If printing on the screen causes flicker, I wonder if by chance you are inadvertently printing and erasing the same thing repeatedly.

 

    -dZ.

[carlsson]

Not sure I can replicate. I tried this code that in theory should illustrate your problem:

const oo = 0
const gb = $0804 + 1 * 8 'green bush
const rb = $0802 + 1 * 8 'red bush
const ex = $0803 + 3 * 8 'exit room

lives = 3

DEFINE 0,4,gfx:WAIT

screen room_1

i = 20
#ch = $0810

loop:
print at 0 color 2, <>lives

#BACKTAB(i) = #ch + 7 : WAIT
i=i+1:IF i>39 THEN #ch = #ch XOR $800 : i=20

goto loop

room_1:
data oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo
data oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo
data oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo
data oo,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,oo
data oo,gb,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,ex,oo
data oo,gb,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,ex,oo
data oo,gb,oo,rb,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,ex,oo
data oo,gb,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,gb,oo
data oo,gb,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,gb,oo
data oo,gb,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,gb,oo
data oo,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,gb,oo
data oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo,oo

gfx:
    BITMAP "..o..o.."
    BITMAP ".oooooo."
    BITMAP "oo....oo"
    BITMAP ".o....o."
    BITMAP ".o....o."
    BITMAP "oo....oo"
    BITMAP ".oooooo."
    BITMAP "..o..o.."

    BITMAP "........"
    BITMAP "....oo.."
    BITMAP ".o.oo..."
    BITMAP "..ooo.o."
    BITMAP "..ooooo."
    BITMAP ".oooooo."
    BITMAP "..oooo.."
    BITMAP "........"

    BITMAP "........"
    BITMAP ".o.oo.o."
    BITMAP "...oo..."
    BITMAP ".oooooo."
    BITMAP ".oooooo."
    BITMAP "...oo..."
    BITMAP ".o.oo.o."
    BITMAP "........"

    BITMAP "oooooooo"
    BITMAP "o...o..o"
    BITMAP "o...oo.o"
    BITMAP "oooooooo"
    BITMAP "o...oo.o"
    BITMAP "o...o..o"
    BITMAP "oooooooo"
    BITMAP "........"

 

Perhaps there is important information left out that I missed when trying to recreate it.

Edited June 24, 2021 by carlsson

[Brian's Man Cave]

dZ....Yes you were right.. I was redrawing the screen in the game loop. I changed it to only draw the screen once and that fixed it!

Thanks

[+DZ-Jay]

10 hours ago, Brian's Man Cave said:

dZ....Yes you were right.. I was redrawing the screen in the game loop. I changed it to only draw the screen once and that fixed it!

Thanks

That'll do it!  We've all been there.  It's those pesky subtle bugs that hurt the most. :)

 

     -dZ.

[+cmadruga]

It is really inspiring to see Brian's interest and grit.

I can't wait to play his future games.

Keep the questions coming, dude.

Edited June 26, 2021 by cmadruga