10 March 2019, 14:26 | #1 |
Lemon. / Core Design
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Displaying hardware sprites to the left of DDFSTART
Was there a method that allows this ? If there is, I forget what it was
Can anyone shed some light on this please |
10 March 2019, 14:36 | #2 |
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10 March 2019, 14:46 | #3 |
Lemon. / Core Design
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Ah cheers, that worked... write to BLP1DAT forces output of all other BPLxDAT too, so DIW can hide that
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10 March 2019, 14:57 | #4 |
WinUAE developer
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Note also possible side-effects:
I think ECS Denise ignores BPL1DAT write if it is done too early. OCS Denise allows it very early horizontally. (Or it was the opposite?) I am not sure if I tested this fully. Also because BPL1DAT write enables Denise bitplane shifters, it can add hidden BPLCON1 offset. Same side-effect as "unaligned" DDFSTRT does. |
10 March 2019, 15:00 | #5 | |
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Quote:
Well, you can use a sprite to cover also the glitch EDIT: Or set DDFSTOP one word more for zeroed contents (in fact it depends on whether you have scroll or other factors what is best to do) Last edited by ross; 10 March 2019 at 15:10. |
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10 March 2019, 15:18 | #6 | |
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Quote:
in any case the shift is also applied when loading the subsequent bitplane data through DMA. So only if you change BPLCON1 dynamically on the line I guess there can be undesidered effect, right? |
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10 March 2019, 15:24 | #7 |
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It is non-issue, I remembered wrong. Next DMA BPL1DAT will "reset" it.
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10 March 2019, 15:42 | #8 | |
Lemon. / Core Design
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Quote:
I have a 32 byte wide screen centralised, and needed to display 32 pixel wide sprites to the left and right of this (as a border). So I've changed DIWSTART to hide the bitplane showing from setting BPL1DAT, but not to hide the sprite |
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10 March 2019, 16:00 | #9 | ||
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Quote:
Have fun! |
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10 March 2019, 17:58 | #10 |
Lemon. / Core Design
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10 March 2019, 20:16 | #11 |
Code Kitten
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I never realized this was possible, neat trick and not too Copper-expensive apparently.
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10 March 2019, 20:24 | #12 |
WinUAE developer
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10 March 2019, 20:37 | #13 |
Lemon. / Core Design
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2x16 (OCS/ECS)
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