Interlace modes, V/H scrolling, Sonic 2 multiplayer queries
Posted: Mon Jul 11, 2016 9:16 am
Hi!
I'm trying to determine how Sonic 2's multiplayer allows for the top half of the screen to vertically scroll independently from the lower half.
In my game I'd like a portion of plane B to remain static whilst the rest scrolls. In my head this could be achieved by setting the scroll size 64 cells high and only utilising the upper 32 for the usual scrolling background, then dropping the V scroll for the static section down to the lower 32. In practice this doesn't work because the H scrolling affects the source line and not the currently rastered line.
But, Sonic 2 looks like it's achieving this. Is this a bonus of interlace mode?
Cheers
I'm trying to determine how Sonic 2's multiplayer allows for the top half of the screen to vertically scroll independently from the lower half.
In my game I'd like a portion of plane B to remain static whilst the rest scrolls. In my head this could be achieved by setting the scroll size 64 cells high and only utilising the upper 32 for the usual scrolling background, then dropping the V scroll for the static section down to the lower 32. In practice this doesn't work because the H scrolling affects the source line and not the currently rastered line.
But, Sonic 2 looks like it's achieving this. Is this a bonus of interlace mode?
Cheers