Dual playfield OCS technical explanation/help please

[Digiman]

Anyone care to explain how bobs and sprite color palettes relate to definition of the two separately defined 16 colour palette of each playfield? Still any of the 32 colours can be used or just either one pair of each 16 colour palette per playfield?

A good web link for these kind of questions welcome too.

[Zac67]

AFAIR OCS dual playfield is 6 bit deep, so it's 8 + 7 colors.

[james666]

Anyone care to explain how bobs and sprite color palettes relate to definition of the two separately defined 16 colour palette of each playfield? Still any of the 32 colours can be used or just either one pair of each 16 colour palette per playfield?

A good web link for these kind of questions welcome too.

OCS displays can have up to 6 bitplanes.  In dual playfield mode you can have up to 3 planes for each playfield, which gives up to 2^3 =8 colours per playfield, one of which is used as a transparent colour in the topmost playfield.  Your dual playfield display then uses up the first 2*8 = 16 colour registers in total.  A bob would have to use of the 8 colours on its own playfield.  The sprites always use the second 16 colour registers regardless of the display type.  I would Google for a scan of the "Amiga Hardware Reference Manual" or "Mapping the Amiga" if you're interested in this stuff.

[Digiman]

OCS displays can have up to 6 bitplanes.  In dual playfield mode you can have up to 3 planes for each playfield, which gives up to 2^3 =8 colours per playfield, one of which is used as a transparent colour in the topmost playfield.  Your dual playfield display then uses up the first 2*8 = 16 colour registers in total.  A bob would have to use of the 8 colours on its own playfield.  The sprites always use the second 16 colour registers regardless of the display type.  I would Google for a scan of the "Amiga Hardware Reference Manual" or "Mapping the Amiga" if you're interested in this stuff.

OOOPS 2x8 colours yes. AGA is 2x16 colours.

Thanks people. So I can use sprites with 16 independent colours? OK I think it will work fine.

For those wondering why? I want to write a simple little game to get back into coding. So then look at the stage from 2:00 to 3:20 in this video

http://www.youtube.com/watch?v=S9P3Lq8g7ck

I'm going to code that up as a 100% accurate conversion.

[Mrs Beanbag]

also bear in mind that when you start the display data fetch 16 pixels early in order to allow fine sideways scrolling, you lose the last hardware sprite, because the sprite data is fetched during this horizontal blanking period.  Some games avoid this by having a slightly narrower playing screen.