[Coco] DynoSprite Demo 1

[Richard Goedeken]

It's true that keeping a static area when using GIME scrolling presents a 
problem.  The Coco needs a "copper" like the Amiga has.  Treating the static 
area as a sprite gets too computationally expensive very quickly.  I have a 
6-digit counter object when can be used for a score, and it takes about 5ms to 
render and erase.  If someone wanted to use DynoSprite with a static screen 
area I would recommend using the same trick with the downsampled HSYNC IRQ 
that you are using for Popstar Pilot.  I think it would work fine even with 
vertical scrolling; I would just place the static bitmap area at some fixed 
location in the physical RAM memory space, and move the screen start address 
between this place and the sliding aperature for the scrolling background at 
the correct time in the IRQ handler.  It would cost the overhead of the 
hi-frequency IRQ at all times, instead of just when a sound is playing, but 
then you could plan for background music.

Richard

On 10/05/2013 05:50 PM, Nick Marentes wrote:
> One problem with using the hardware scrolling capabilities of the GIME is that
> EVERYTHING moves.
>
> You can't have a static spot on the screen for the display of score and other
> game info and you end up adding code to manage this with a redraw and undraw
> of these areas.
>
> That's why it was important for me to create a split screen system for my game
> but this only works for horizontal scrolling. As far as I know, vertical can't
> be split the same way.
>
> Nick
>
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