20 November 2017, 16:49 | #21 | |
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20 November 2017, 17:20 | #22 |
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Of course, 16 colour (4 bitplane) hires laced (640x512) is precisely double the requirements of a 320x256 8bpp screen - so the requirements there would be the same. However, I'll pass that back to you and ask how quickly we could shift that amount of data around? Are the hires laced screens particularly fast? And then there's the memory requirements for day to day usage - don't forget that the Amiga was initially released with just 256Kb of RAM - a 640x512x16 screen would mean that space would be very tight - it would take up more than half available RAM. You'd need an upgraded Amiga to do that. Hell, even with the A500 512Kb, you can't have very many hires screens open at once unless you drop to 4 colours or less. Miggy4Eva: Hell, if we're shooting for things the Amiga never had (which is a pointless exercise) then how about a 1-pixel resolution copper? Might as well if we're using things that never were in order to prove some sort of superiority contest The initial post (and thus the point of this thread was to ask what advantages planar modes had over chunky. The reduction in graphics memory needed was basically the entire reason for planar - and lest we forget, using chunky graphics modes for 3D games was so far in the future at the Amiga's release date that it didn't figure in their design. |
20 November 2017, 17:22 | #23 | |
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The difference is in throwing the 2d graphics and sprites around, masking sprites over others etc. There are easier ways to perform those operations on planar-formatted graphical data, which uses both less CPU / coprocessor resources, and less RAM. |
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20 November 2017, 17:24 | #24 | |
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To say "Oh I wish the Amiga had a Chunky mode, it would have helped with 3d" is crime of the century and derailing the thread, huh? |
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20 November 2017, 17:30 | #25 | |
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And a massively higher price tag, but don't let that get in the way of your Amiga-master-race fantasies.
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20 November 2017, 21:15 | #26 |
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To be fair, there was the MSX2 from 1985 which had an 8-bit (256 color) chunky mode at a lower price tag. I guess the main problem in terms of hardware complexity would have been the number of color registers - 256 12-bit Registers need already ~20k transistors, quite a lot at that time. The MSX2 for that reason used direct 8-bit-RGB (3 red bits, 3 green, 2 blue) without a palette. Interesting if they could have used something like 3-bit EHB in the Amiga (5 bit palette, 3 bit intensity).
In principle, one could also use chunky modes with less than 8 bit (although only powers of two a re practical), a 4 bit nibble chunky mode would have been certainly better suited for single pixel operations. But as most CPUs do not have efficient special instructions to handle nibbles, it would have meant lots of masking + shifting, making it slower than a byte chunky mode for a lot of things. Probably that's why it wasn't considered. What would have been comparatively easy to implement in the Amiga: a 16-bit, 4096 chunky mode in halve the x-resolution. Bit of a waste of memory, but C64 lowres mode on steroids! |
20 November 2017, 21:45 | #27 |
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Do we have threads about Chunky/Planar every 4 months? Does someone keep a calendar for them?
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20 November 2017, 21:57 | #28 |
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The same 256-colour bitmap image is, certainly. A 32-colour image in chunky format, though, would either wastefully allocate 1 byte for each 5-bit pixel, thus increasing the required storage space by more than 50%, or pack the bits densely, 8 pixels to 5 bytes - thus throwing away the speed advantage of chunky, since it would be more even more painful to handle with the CPU than planar data.
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20 November 2017, 22:10 | #29 | |
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20 November 2017, 23:10 | #30 |
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Hi guys thanks for the replies. Like I said in the first post by the time they got to 256 colours, they might of realised that perhaps the Chunky mode might be best and they could of thrown one in the mix, using 1 word for each pixel. I don't know how much work that would of had to have been to the chipset. I know that the origional Amigas didn't come with much memory 256kb was not much but that would of been enough for slide shows, like they did with the HAM mode
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21 November 2017, 00:35 | #31 | ||
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Last edited by Dunny; 21 November 2017 at 00:41. |
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21 November 2017, 16:49 | #32 | ||
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320x256 with 4 bpl would provide enough bandwidth for 160x256 in 8 bit chunky. 640x256 with 4 bpl -> 320x256 8 bit chunky. Of course 4 bit chunky in 160x256 resolution would still be usable. One problem with 8 bit chunky would be the color management. Amiga used 32 palette entries even for the 64 color mode to save gates, going up to 256 palette entries would be expensive. Quote:
Doing it in a hack-style manner would still be better for some rendering techniques even if chunky pixels would be interleaved in some manner. Still couldn't be as crappy as the [IBM][PC] VGA Mode-X where pixels are chunky distributed over 4 planes and the processor having direct access to one plane at a time. But we liked it! |
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21 November 2017, 18:42 | #33 |
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21 November 2017, 19:38 | #34 | |||
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22 November 2017, 12:32 | #35 |
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08 December 2017, 07:57 | #36 | ||
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I remember very clearly at the time (thanks to hours trying to get my school computers to run it) that if you had a 486SX (i.e. no FPU) and bog-standard VGA, you'd have to reduce the size of the play viewport to get it to run at a decent clip. Getting it to run remotely smoothly in full-screen mode usually meant a VESA-compatible graphics card was necessary on anything less than a 486DX2. The concept of first-person games built around a raycasting engine was an outgrowth of people like John Carmack, Doug Church, Michael Abrash et al. discovering something to which the mid-evolution PC architecture turned out to be well-suited (though it required DOS extenders and the like to make it work). It simply wasn't remotely feasible during the period in which the Amiga was designed (limited transistor counts and a worldwide RAM shortage being limiting factors). I think it's also worth bearing in mind that even if you had a 486DX2 with a VESA card in about 1994, the architecture was singularly bad at reproducing the kind of "2D" games which were the norm until the early-mid '90s. I vividly remember playing Project X on a friend's PC with that exact spec and almost getting a headache from how jerky the horizontal scrolling was. I'd always thought it was every 4px on OCS/ECS and every 2px on AGA (hence the original AB3D and Gloom, which took advantage of that). Please correct me if I've been labouring under a misapprehension! |
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08 December 2017, 08:37 | #37 |
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Chunky modes were possible on Amiga with the custom chips, but they were very low-res (lower than 8 bit computers).
Ambermoon used hybrid chunky mode for the floor/ceilings. There is also a chunky screen mode with using the copper: http://aminet.net/package/dev/misc/chopper Some demo scene productions used these hybrid modes, but they were not very practical for gaming, especially on the Amiga were everyone was used to pixel graphics. |
08 December 2017, 10:24 | #38 | |
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The argument about using a faster copper to create e.g. 1px copper chunky is bullshit, because even if it was possible to fit in-between all the other dma cycles, it would eat so much bandwidth that the rest of the system would not be able to do anything.. |
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08 December 2017, 23:50 | #39 |
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Thanks @hooverphonique - that's really useful info!
(Also, you're named after a really cool band... ) |
11 December 2017, 13:24 | #40 |
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