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Copper Tricks, and Featspage  1 2 
Erik Bauer
Italy

Posts 303
05 Feb 2012 09:14


Team Chaos Leader wrote:

I use the copper to make the entire screen wave around every time the player drinks a shot of vodka.
 
 

Reminds me "Legends of Valour"

Rf Tx
Finland

Posts 15
05 Feb 2012 14:48


Erik Bauer wrote:

 
Thierry Atheist wrote:

    Hmmmm, what game really took advantage of a Copper list, then?
   

   
    Watermirror effects in games like "The killing game show" or "Desposable Hero" come to mind. Plus all the shaded sky background you can see in most of Amiga platformers, or the tricky color effects used in a Graphic Adventure whose name I totally forgot, but the programmers stated it had 256 colours on screen on an ECS Amiga.
 

 
  EXTERNAL LINK 
  Some suggested that Universe used "secret" Amiga gfx mode called HAM5 (5 bitplanes, 8 base colors or 16 base colors & only blue color value could be modified). Probably it switches 32 color palette by using the copper.
 

Erik Bauer
Italy

Posts 303
05 Feb 2012 16:30


RF TX wrote:

Erik Bauer wrote:

 
Thierry Atheist wrote:

    Hmmmm, what game really took advantage of a Copper list, then?
   

   
    Watermirror effects in games like "The killing game show" or "Desposable Hero" come to mind. Plus all the shaded sky background you can see in most of Amiga platformers, or the tricky color effects used in a Graphic Adventure whose name I totally forgot, but the programmers stated it had 256 colours on screen on an ECS Amiga.
 

 
  EXTERNAL LINK   
  Some suggested that Universe used "secret" Amiga gfx mode called HAM5 (5 bitplanes, 8 base colors or 16 base colors & only blue color value could be modified). Probably it switches 32 color palette by using the copper.
 

Yeah, the latter was exactly my tought.

BÝrge NÝst
Norway

Posts 58
05 Feb 2012 19:59


Thierry Atheist wrote:

Hmmmm, what game really took advantage of a Copper list, then?

Oh, and if we can deviate from games then NewTek had a hires 16c mode that switched colours every line. I think. Pretty sure some gfx package supported that mode.

Offtopic: And since we mentioned HAM I always thought pinball games like Pinball Fantasies would be well suited to use HAM - you have very few moving parts and you only need a 3 pixels wide sprite on the left and right edges of the objects to hide the transitions needed to get back to the original pixel colour in the background.
This is where the copper comes in handy to change X position dynamically, and even to re-use sprites if you need more than 8.

Rf Tx
Finland

Posts 15
05 Feb 2012 20:31


Erik Bauer wrote:

RF TX wrote:

 
Erik Bauer wrote:

   
Thierry Atheist wrote:

      Hmmmm, what game really took advantage of a Copper list, then?
     

     
      Watermirror effects in games like "The killing game show" or "Desposable Hero" come to mind. Plus all the shaded sky background you can see in most of Amiga platformers, or the tricky color effects used in a Graphic Adventure whose name I totally forgot, but the programmers stated it had 256 colours on screen on an ECS Amiga.
   

   
    EXTERNAL LINK   
    Some suggested that Universe used "secret" Amiga gfx mode called HAM5 (5 bitplanes, 8 base colors or 16 base colors & only blue color value could be modified). Probably it switches 32 color palette by using the copper.
   
 

 
  Yeah, the latter was exactly my tought.

Wikipedia mentions HAM5
http://en.wikipedia.org/wiki/Hold-And-Modify#Original_Chip_Set_HAM_mode_.28HAM6.29

"A similar mode, HAM5 is also available but not as flexible nor widely used."
???


Jakob Eriksson
Sweden
(Moderator)
Posts 1097
05 Feb 2012 21:32


Something like that is mentioned here:
 
  EXTERNAL LINK 
  whatever is described there works only on Amiga upgraded to ECS Agnus, but with 512k slow mem + 512k chip mem. weird...

And Piru says HAM5 is just HAM6 but not using the 6th bitplane:
EXTERNAL LINK

Nixus Minimax
Germany

Posts 312
06 Feb 2012 09:48


Børge Nøst wrote:
Offtopic: And since we mentioned HAM I always thought pinball games like Pinball Fantasies would be well suited to use HAM - you have very few moving parts and you only need a 3 pixels wide sprite on the left and right edges of the objects to hide the transitions needed to get back to the original pixel colour in the background.

You don't need a sprite nor anything else. HAM6 has four modes for each pixel: modify B, modify R, modify G, palette. So if the border pixels of each object is chosen from the 16-colour palette, you won't get any unexpected transitions. AFAIR the sprites can also select any colour from the 16-colour palette but if placed randomly will also produce a colour trail in the HAM background.

With the HAM mode you can do some funny tricks. E.g. you can shift three consecutive frames by one pixel each so that in the three frames the R, G and B components overlay at a single place of the screen yielding an almost true-colour screen.

BÝrge NÝst
Norway

Posts 58
07 Feb 2012 06:03


Nixus Minimax wrote:
So if the border pixels of each object is chosen from the 16-colour palette, you won't get any unexpected transitions.

Yes, but that limits your colours for the picture/background in the first place. And the right side of the object will have upto 3 pixels in the wrong colours before you get to the original colour.
Use a 3 pixels wide sprite on the left side and you can mask the initial change to match your HAM bob, and 3 on the right side to hide the transition back to the original background. With that you can move a HAM bob over any HAM picture and see no artifacts. Might take some cpu time or memory to process it though.


Rune Stensland
Norway
(MX-Board Owner)
Posts 876
07 Feb 2012 13:44


The year is 1990
The demo is Copper master by angels:

EXTERNAL LINK 
EXTERNAL LINK 

Matt Hey
USA

Posts 783
07 Feb 2012 13:50


Børge Nøst wrote:

  Oh, and if we can deviate from games then NewTek had a hires 16c mode that switched colours every line. I think. Pretty sure some gfx package supported that mode.
 

 
  You mean Sliced HAM mode (SHAM)?
 
  "Sliced HAM mode, also known as dynamic HAM mode uses the Amiga's standard HAM6 color mode, 6-bitplanes (4 bitplanes for the base colour palette of 16 colors and 2 bitplanes for modifying the base colors). It requires the use of the 'copper' coprocessor to increase the number of colors available on screen to the full 4096 palette by reprogramming the color registers every scanline. Slicing was common when using copper graphics in demos, image manipulation, and certain games. It is also possible to reprogram color registers at arbitrary points along individual scanlines, meaning that individual scanlines can be sliced in the same way."
 
  Quote from EXTERNAL LINK 

  Here is the only SHAM paint program...
 
  EXTERNAL LINK 
 
  It might be useful for testing SAGA as the screen size and individual pixel colors can be changed. It still works on AmigaOS 3.9 with my 68060 so seams to be pretty well written even if rather basic as a paint program goes.
 

Marcel Verdaasdonk
Netherlands

Posts 4045
08 Feb 2012 22:49


Demo's would be a bad example since they generally used smaller resolutions to work around bandwidth restrictions.

Programs how ever do not have that luxury, I wonder where it would have it's flaws.

SHAM is a good example of how a Copper was abused. ;)

BÝrge NÝst
Norway

Posts 58
09 Feb 2012 01:35


Matt Hey wrote:
  You mean Sliced HAM mode (SHAM)?

That wasn't what I was thinking about, but it works too. Same thing.

I think perhaps the NewTek demoreel had a pciture in 640x400 with this sliced 4bpp mode. A rather famous picture of beach pebbles and rocks IIRC.


Matt Hey
USA

Posts 783
09 Feb 2012 08:14


Børge Nøst wrote:

Matt Hey wrote:
  You mean Sliced HAM mode (SHAM)?

  That wasn't what I was thinking about, but it works too. Same thing.
 
  I think perhaps the NewTek demoreel had a picture in 640x400 with this sliced 4bpp mode. A rather famous picture of beach pebbles and rocks IIRC.

I believe NewTek called it Dynamic HiRes and it's listed under SHAM (variation?) in the Wiki link I posted...

"Dynamic HiRes uses a similar palette changing technique. Where SHAM is limited to low resolution HAM modes, Dynamic HiRes uses the 4bitplane (16 colour) high resolution modes. Each scan line can have a unique 16 colour palette. Unlike the low resolution HAM6 modes, the hires screen modes of the original chipset have no ability to modify the base colors to get more than 16 colors per scan line."

MacroPaint (linked above) requires hires and works with or without interlace (i.e. 640x400) as well as reducing the limitations on colors using the copper. I would guess that it uses a 4 bit depth in hires interlaced but it doesn't multitask so I can't use Scout to verify.


Marcel Verdaasdonk
Netherlands

Posts 4045
19 Feb 2012 09:17


Matt do you have a good idea how this could be expanded on in the Natami?

Matt Hey
USA

Posts 783
19 Feb 2012 13:58


Marcel Verdaasdonk wrote:

  Matt do you have a good idea how this could be expanded on in the Natami?
 

 
  Dynamic HiRes addressed a limitation of the hardware that the Natami doesn't have. We will have high depth chunky that can produce higher resolutions and more colors, is easier to use and is easier for the OS to support. MacroPaint is a relic on the Natami but should be useful for testing and debugging the copper as the copper list should be dynamically changed (for testing) as pixels on the screen are altered. The Natami should support Dynamic HiRes as well as other programs that play with the copper in an AmigaOS friendly way.
 

Marcel Verdaasdonk
Netherlands

Posts 4045
19 Feb 2012 20:26


I meant as in theoretic maximum, This would be a eye opener.

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