Re: A82: image size and location
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Re: A82: image size and location
ilya winham wrote:
> When you want to display a TitlePic most programmers usually do this:
>
> ld hl,title ; hl points to teh location to copy from
> ld de,$88B8 ; de points to GRAPH_MEM, to location to copy to
> ld bc,132 ;Copy 132 bytes
> ldir ; Do it
> ROM_CALL(DISP_GRPH) ; Copy GRAPH_MEM to the display controller
> #1 How do you know where it will be displayed?
The offset. If you want a pic to start 16 pixels into the first line,
load de with GRAPHMEM+2. If you want it to start halfway down the screen,
do GRAPH_MEM+(96[Width of the screen]*31[Halfway down])
> #2 How do you calculate the size in the ld bc,??? command?
The size of your picture. The example you showed is 25 bytes, I think
> #3 How can you make titlepics?
Draw the picture. IF you want a pixel on, do a 1. Of not, do a 0. Then,
convert to hex (For simplicity- in hex each byte is two characters.)
So, this is the picture
0000111111110000
0001111111111000
0011111111111100
0111111111111110
1111111111111111
%00001111 = $0F
%11110000 = $f8
PyramidPic:
.db $0F, $F0
.db $1F,$F8
.db $3F,$FC
.db $7F,$FE
.db $FF,$FF
Now, to display it in about the center of the screen,
ld hl,PyramidPic
ld de,GRAPG_MEM+((29*96)+45)
d bc,10
ldir ; Do it
ROM_CALL(DISP_GRPH) ; Copy GRAPH_MEM to the display controller
This ought to work fine
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