23 June 2013, 03:54 | #21 | |
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I'm not just talking about animated movies, I'm thinking about pre-calculated things like lighting, physics and movement paths for objects in 3D scenes. Last edited by NovaCoder; 23 June 2013 at 05:25. |
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23 June 2013, 11:12 | #22 |
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And it still is far away from truth! First, not many demos use physics. And lighting is perfectly possible (and done) in realtime, same for movement paths, splines are used there and coding a fast spline routine isn't that hard. Precaclulated are most of the time sine tables (or other trig tables for that matter) but the "real" stuff is done in realtime.
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23 June 2013, 21:13 | #23 |
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Kovacm: You might want to talk to Leonard from Oxygene about his demos. He's still around. Look here: http://leonard.oxg.free.fr/
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23 June 2013, 22:30 | #24 | ||||
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"are best Amiga 1200 demos with most complex 3D scenes BUT for STOCK A1200 (14MHz - with FastRAM)." link Quote:
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so I do not understand why did you post bunch of pictures... ?!? |
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23 June 2013, 22:42 | #25 | |
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@Frog @UberFreak thanx both, I will check demos and nfo files and I will bring out my A1200 (I need to find FastRAM upgrade) to check all this demos on real hardware! |
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24 June 2013, 14:37 | #26 | ||||
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Not sure but can you provide similar topic on dedicated ST forum where some Amiga guy starting similar topic. We can only compare something that is comparable - ST and A500 can't be compared as they are not comparable. btw - once again - 3D even in software must be rendered at final buffer - this is my point with pictures - video buffers and video output capabilities are so different that it is really hard even to think about honest ST comparison with A500. For example i can set 640x400 on Amiga - i can even force this resolution to be less flicker (by shortening video frame on OCS or explicitly by reducing number of lines to be displayed on ECS) - or i can be nasty and use LCD as display thus no flicker at all, then i can draw 3D on such screen but still i can introduce color and this is out of ST capabilities - how we can compare this? Gain from memory organization on ST is mostly where chunky translation is used - then yes, ST will be slightly faster but do really that speed will translate to final effect? when you need push PSG vol register to emulate PCM channel for example? Let me show this in that way - nice example [ Show youtube player ] vs very good [ Show youtube player ] or [ Show youtube player ] i like those ST demos, no doubt but i think that difference (some imperfections on ST) are obvious - and how to compare various taste? pears to peaches... So sorry, no offense but we can't compare ST with A500 and we can't compare Falcon with A1200 - both comparisons will be simply unfair. |
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24 June 2013, 16:46 | #27 | ||
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There are some myth around Falcon's memory bus (and Amiga also).
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Regarding CPU, it has access to ST-RAM(chip-ram) every odd bus cycle. It means 4th CPU cycle access - 4Mhz. And It has Full Speed access to Fast-Ram. Quote:
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BusSpeedTest 0.19 (mlelstv) Buffer: 262144 Bytes, Alignment: 32768 ======================================================================== memtype addr op cycle calib bandwidth chip $000B0000 readw 1052.4 ns normal 1.9 * 10^6 byte/s chip $000B0000 readl 1051.8 ns normal 3.8 * 10^6 byte/s chip $000B0000 readm 1052.2 ns normal 3.8 * 10^6 byte/ And for Falcon: Code:
NemBench v2.1 - precision CPU/FPU profiler. Linear 32bit read (ST-Ram) -> 5.475 MByte/sec (~103%) Linear 32bit write (ST-Ram) -> 6.660 MByte/sec (~103%) Linear 32bit copy (ST-Ram) -> 3.336 MByte/sec (~103%) |
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24 June 2013, 21:01 | #28 |
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24 June 2013, 22:54 | #29 |
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25 June 2013, 20:39 | #30 |
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@pandy71
offtopic - I am curious: how these images are reproduced on Amiga? My first guess is "Spectrum 512" in hi-res (palette changing trick)? right? |
25 June 2013, 21:26 | #31 | |
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Was there a hires version of Spectrum 512? I would have thought that the limit of changing one of four colors per run of 20 pixels would have made the technique almost useless. |
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25 June 2013, 22:18 | #32 | |
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^ you can see how it will look like here http://pouet.net/prod.php?which=12237
"Each picture has a resolution of 640x400 and can contain up to 14.000 colors out of a palette from 29.791 colors." Quote:
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25 June 2013, 22:18 | #33 | |
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Sometimes better effects can be achieved with hybrid solution: http://www.ximagic.com/q_index.html with HAMLAB (Ximagic Quantizer preproces image to reduced amount of colours, then HAMLAB trying to fit this in PCHG limitations - dithereing/noise shaping is extremally important and HAMLAB have some limitations also seems that is not very stable in terms of quality) - however using smart (psycho-visually tuned - shape recognition? - neural networks?) or at least decent modern (http://members.ozemail.com.au/~dekker/NEUQUANT.HTML , http://moonflare.com/code/scolorq/) color reduction algorithm horizontally oriented (to fit optimally in Copper limitations) with some direct hardware access (PCHG is a bit limited to made standard OS friendly - interlace offer less color changes on screen), probably those results can be much better, perhaps near perfect-optimal. As there is no PCHG compatible viewer for PC (i don't know such viewer) , those pictures are changed from PCHG IFF to 24 bit png by HAMLAB - this can be seen as loss free conversion thus WYSIWYG. http://ulozto.net/xFt2Afu2/pchg-7z some examples in PCHG IFF (thus Amiga or WinUAE required with at least freeware Mostra) |
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25 June 2013, 22:36 | #34 | |
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one color change per 8 hires pixels - PCHG limit color changes to H Blank time thus no more than 7 - 9 per scanline and only for frame not field - OS friendly - manually Copper can do more (but not more than 50 few changes per scanline). |
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25 June 2013, 23:58 | #35 |
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^^
can I make one observation? on ST, coders need, as you said "to emulate" (I would prefer phrase "to find way") to achieve Amiga capabilities. One of need was to display more than 16 colors onscreen so Atari coders find a way in 1987.: Spectrum 512 (http://www.asterius.com/atari/spectrum.html) It is nice to see that Amiga coders adopt this idea. as I said before: I want to see how far coders manage to push limits of hardware boundaries btw "manually Copper can do more (but not more than 50 few changes per scanline)" - copper will do this with 0% CPU time, and some bus time, right? and one more thing: how much bus time will consume hires with 4 bitplanes on OCS/ECS? Last edited by kovacm; 26 June 2013 at 00:05. |
26 June 2013, 07:31 | #36 | ||
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Raster interrupts are OK - its nice that Atari ST coders adapted idea from Atari 400/800 and Commodore 64 - this provide impressive result considering Jack Tramiel cost reduction concept and limited amount of time to design ST. Amiga is slightly different (more comparable to Atari 400/800 but there is no ANTIC and there are some fundamental differences how video data are processed) and most of this type operations is performed by Copper (with all pros and cons). Raster interrupts can be used on Amiga without problems (necessary HW exist ad trig particular behavior on CPU side) but in multitasking environment it is better to use dedicated HW that provide HW synchronization with time critical event (as nature of the multitasking systems is purely asynchronous). Anyway Raster interrupt is CPU (especially modern one) not friendly and simply this is dirty (8 bit time) hack. Quote:
To conclude - you may assume that Lores 4 bitplanes/Hires 2 bitplanes are without speed limitation on CPU side (unless Copper/Blitter heavily used) - this is similar to ST. Also quite important difference is that Copper/CPU can manually feed BPLxDAT registers thus with lower number active bitplanes higher number color registers can be used (at least at some special cases and under some limitations) - this is not frequently used feature - in theory with clever pattern and temporal dither perhaps this can be used as substitute for tricky video mode - as HAM doesn't work in Hires (OCS/ECS) then we can't use HAM to improve this kind of functionality with software driven BPLxDAT (but we can in Lores) - not sure but as a technical concept probably you can do video fully pure software pumped (by CPU or Copper) just placing video data directly in BPLxDAT... |
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26 June 2013, 10:28 | #37 | |
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nice. did not know that it use only 2 bitplanes. we should made one nice site about all this stuff!...
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btw this is offtopic but: what about PCHG animation/video? is anybody done this on Amiga? on Atari STe, Mr. Petari made 50fps video playback from CF Card connected to ROM port. Video is up to 416x228px, 48 colors per scanline, 50fps for flickering and additional perceptual colors (30000). Speed of CF card ROM port adapter is more than 3.5MB/s(!) but for video and sound 2.4MB/sec is enough. [ Show youtube player ] [ Show youtube player ] btw2 do you have some reference that palette changing trick for displaying images are made on XL or C64 prior 1987.? |
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26 June 2013, 10:46 | #38 | ||||
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[ Show youtube player ] But as there is no good conversion software then HAM is far from perfect. On AGA all efforts was made to make real time transcoding ie not preconverted but convert on the fly (with decoding) video from different formats (such as MPEG and similar). Quote:
Same rule as previously and obviously when you use temporal dithering there is no 50fps also cinema source (film) is 24 fps - no reason to push over this especially that Amiga can change vertical frequency easily and create 24/48 fps modes to render such video without time jitter. In case of Amiga - CHIP BUS seem to be limit - absolute maximum is hires 4 bpl, AGA is much better on this. Not sure - probably on those time people was focused on different aspects, later temporal dithering and similar tricks was introduced - i think break trough was related to widely variable high quality pictures (scans) mostly as GIF and JPG. Last edited by pandy71; 26 June 2013 at 10:56. |
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26 June 2013, 11:13 | #39 | |
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on Atari demand for more colors on screen was because of 3D software, CAD 3D, to be able to show results as good as possible. (follow the link that I left few post above for more info) Last edited by prowler; 27 June 2013 at 01:03. Reason: Fixed quote. |
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26 June 2013, 11:43 | #40 | |
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http://eab.abime.net/226098-post7.html http://ada.untergrund.net/forum/inde...um=4&topic=442 As i said previously - some of HW functionality already available in Amiga make Amiga developers more "lazy" |
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