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Old 13 October 2019, 22:38   #5
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geldo79's Avatar
Join Date: Oct 2019
Location: Eydelstedt / Germany
Age: 40
Posts: 32
Originally Posted by dodke View Post
1. Is the bob static? Try moving the bob on the screen and you should see what the issue is. The bob is not static. I can move it over the background screen pixel by pixel. It looks good. I use

move.w #40-4,$60(a5) ; BLTCMOD
move.w #-2,$62(a5) ; BLTBMOD
move.w #-2,$64(a5) ; BLTAMOD
move.w #40-4,$66(a5) ; BLTDMOD

move.w #(16*64)+2,$58(a5) ; BLTSIZE

When I chose the 16x32 bob (with empty area on the right), I have to use a 16x32 mask (thus, also contains the empty area on the right side), and set

move.w #0,$62(a5) ; BLTBMOD
move.w #0,$64(a5) ; BLTAMOD

to get the same result. The only issue I see, is when the bob leaves the screen on the left/right/top/bottom of the screen (I want to let the bob come into the opposite side if it leaves the screen boundries). But that problem I have with both configurations.

Originally Posted by dodke View Post
2. You don't need it for bobs. But for example if you are drawing a rectangle of any size you'd probably want to use these registers. The blitter will only copy words / 16 pixels but you can set these registers to fine tune the left (first word of a line) and right (last) edges of the rectangle to be at any pixel position.
Ok. Sounds plausible.
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