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Old Yesterday, 14:28   #81
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Originally Posted by Steril707 View Post
@DamienD: I think this kind of discussion is rather beneficial, and even if personally I will stay with the way the game looks, this exchange of ideas might be interesting for other people who want to code something..

So, everything's fine...

Plus, I'd rather have some discussion in this thread than none...
OK, lets back to business = talking what can be done on Amiga with this type of games

Is my guess correct that you use 4 sprites for first wave of enemies and another 4 for the second?

You multiple them vertically but not horizontally??

I have now an idea how to multiply 4 HW sprites in single line.
4HW sprite makes single 32px wide 15colour object which we want to mirror lets say 128px to the right.

We would have such copper code:

Set sprite 0 position to X
Set sprite 1 position to X
Set sprite 2 position to X+16
Set sprite 3 position to X+16
Set sprite 4 position to X+128
Set sprite 5 position to X+128
Set sprite 6 position to X+128+16
Set sprite 7 position to X+128+16
Wait till next line position X (plus minus 16px space)

Every vertical blank you would change this X position in order to move the sprites to the left.

It is really important to understand that in 6 bitplanes we can point to execution copper command every 8pixels. The copper in order to position the sprites accordingly would have to change execution point following the sprite moving to the left.

Lets say we have as in your case four 32px height objects. That would mean we would have to update 4x32x9=1152 Words in copper list every Vblank.
Another disadvantage is that using the code above you can move the sprite every two pixels. If you want to move it every single pixel you would have to add another 8 copper instructions which would cause another burden on DMA.

hmm, I would not be sure would we be able with such dma burden to keep 50Hz. There is also another idea which comes to mind.

We can create enemies as 5 colour objects as well using Attach bit trick, but you would have to use the same 5 colours for All of them. hmm, i guess it would be better to use different 3 colours samples which can look more colourful and with some skilled graphician they can still look good.
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Old Yesterday, 15:38   #82
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@Trachu: Yeah, you guessed right with the Sprite allocation.

From having a look on it, I guess what you describe is possible, but rather complicated and kind of unflexible.

I am not really in need of more Objects, though, since in addition to the Sprites I still have my merry old BOBs flying around, which only have the problem of being a bit less colourful than the Sprites.

Building such a powerful sprite multiplexer would be an interesting exercise, though...
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