| From: | Curt Esser |
| Date: | 12 Aug 99 at 00:39:18 |
| Subject: | Re: 16Bit Chunky, well, any bit, really... |
Hi Ayar
On 11-Aug-99, Ayar Baboon wrote:
>
>> In chunky, each pixel is defined by one or more full
>> bytes - this limits the
>> display to multiples of 8 - 8bit, 16bit, 24bit, etc.
>
> Ah, okay. And those machine's gfx hardware would be designed to read
> and write whole bytes?
Yes, since PC's can't do planar graphics modes.
>
>> An 8bit chunky gives you the same 256 colours as an
>> 8 plane Planar display,
>> but as you can see, it is much easier to handle
>> since you don't need to go
>> searching for the bits in all the bitplanes...
>
> Rather than getting a byte value, in planar you have to get 8
> individual bits, and put them together? That what you mean?
Yes, on an 8bit (256 colour) screen. Or 7bits for a 128 colour screen, etc.
There are some advantages to planar graphics - one of which is that if you
use for example a 4bit screen (16 colours) the graphics will be handled
twice as fast.
Also, you can do tricks like dual-playfield, where 2 separate 4bit displays
can move independantly of each other, although both are displayed on the
same screen.
>
>>
>> Unfortunately, you can't display a chunky directly
>> on a standard
>> (non-GFX-card) Amiga, so you must convert it to a
>> planar bitmap first.
>
> Ah. XTreme racing kept wittering on about c2p routines...
> Must have been, they used chunky to rotate textures quickly, then the
> clever bit was quickly changing to planar...
> Nice!
Yes. This is the same sort of thing you can do with things like the Mildred
library, or Fred's NCS chunky commands. And at the same time, provide GFX
card compatability by simply sending the chunky direct to the GFX card
screen.
The only drawback is that the target system must have a fast enough
processor to keep up with the overhead of the c2p conversion (or a GFX
card)
In other words, forget about it if you want your program to work on an
unmodified 1200...
Later...
Yours electronically,
Curt Esser
camge@ix.netcom.com
http://members.xoom.com/Curt_Esser/
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