Drawing playfields from data statements

[iesposta]

Man this replay editor is giving problems...

 

I was trying to add:

^{Also, to draw another playfield, it won't clear what already has been drawn (in DPC+) so I have to add "pfpixel current_col print_row off" before the "... print_row on"}

[bogax]

The code is a big counter.

It counts by bits, bytes and data statements

It maintains a counter in parallel that counts

by columns and rows. The columns advance for every bit

and the rows for every fourth byte.

The bytes go 0,1,2,3...

Three is the fourth byte so the code masks the lower

two bits (ands byte_ptr with a mask that happens to equal

three, ie byte_ptr & 3) and increments the row if they equal

three.

 

To do 28 bits the easiest would be to check the column

and if it's 27 reset it to 0, increment the row and skip

the rest of this byte and go to the next byte.

 

 dim print_row = a
 dim current_col = b
 dim current_bit = c
 dim current_byte = d
 dim ds_index = e
 dim byte_ptr = f

WritePFChunk

 print_row = 0
 current_col = 0
 for ds_index = 0 to 3

 for byte_ptr = 0 to 175
 current_bit = $80
 on ds_index goto DCASE0 DCASE1 DCASE2 DCASE3

NEXT_BYTE
 next
 next
 return

DCASE0 current_byte = L4_0[byte_ptr] : goto BIT_LOOP
DCASE1 current_byte = L4_1[byte_ptr] : goto BIT_LOOP
DCASE2 current_byte = L4_2[byte_ptr] : goto BIT_LOOP
DCASE3 current_byte = L4_3[byte_ptr]

BIT_LOOP
 if current_byte & current_bit then pfpixel current_col print_row on else pfpixel current_col print_row off 
 if current_col = 27 then current_col = 0 : print_row = print_row + 1 : goto NEXT_BYTE
 current_col = current_col + 1
 current_bit = current_bit / 2
 if current_bit then goto BIT_LOOP
 goto NEXT_BYTE

Edited November 20, 2012 by bogax

[+Random Terrain]

Don't know if it will help DPC+ users, but this should help everybody else:

 

http://www.atariage.com/forums/blog/302/entry-9759-small-update-for-visualbb/

 

Visual batari Basic now has the ability to convert normal playfield data to data that looks like this:

 

   data _Maze_01
   $7F,$FF,$FF,$7F,$60,$06,$60,$60,$66,$66,$66,$66,$60,$00,$00,$66,
   $67,$67,$7E,$66,$60,$60,$00,$60,$66,$66,$66,$7E,$60,$06,$06,$60,
   $66,$66,$66,$66,$60,$60,$00,$60,$7F,$FF,$FF,$7F
end

 

It displays just as fast as this would:

 

     playfield:
     XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
     X........X............X........X
     X........X............X........X
     X..XXXX..X..XXXXXXXX..X..XXXX..X
     X..............................X
     X..............................X
     X..XXXX..XXX..X..X..XXX..XXXX..X
     X.....X.......X..X.......X.....X
     X.....X.......X..X.......X.....X
     X..X..X..XXXXXX..XXXXXX..X..X..X
     X..X........................X..X
     X..X........................X..X
     X..XXXX..XXXXXX..XXXXXX..XXXX..X
     X..............................X
     X..............................X
     XXXX..X..XXXXXXXXXXXXXX..X..XXXX
     X.....X..................X.....X
     X.....X..................X.....X
     X..XXXXXXX..XXXXXXXX..XXXXXXX..X
     X..............................X
     X..............................X
     XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
     ................................
end

 

And don't worry, VbB automatically reverses the appropriate numbers so they can be used directly with playfield variables.

 

Check out my reply in jwierer's blog for more information.

 

 

 

Update:

 

I found out from RevEng that this will definitely NOT work for DPC+ users. But it will help regular kernel bB users who want to instantly change parts of the screen.