Re: A89: Re: Making a faster map routine(round #2)


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Re: A89: Re: Making a faster map routine(round #2)




I have tried doing this and am getting nowhere.  Could
somebody make a small example that shows how to do
this with one plane and one sprite repeated over the
screen?  Thanks


> Well, say you have 16x16-pixel sized sprites and
> want to plot them on the entire
> LCD (i.e. no status bar)...
> 
> FIrst, create a buffer that's 32 bytes by 144 rows
> big.
> 
> Now say you have an (x,y) that's your upper left
> corner of the map part you want
> to plot, in the form of (16*x0 + x1, 16*y0 + y1),
> where (x0,y0) are the "tile"
> coordinates and (x1,y1) are the "in-a-tile"
> coordinates for sub-tile accuracy :)
> 
> Using (x0,y0) to determine the tile that will be
> (partly) in the upper left
> corner of the LCD, plot the desired part of the map
> into the buffer (putting a
> 16x16 sprite on a word-aligned place in that buffer
> is easy, so I won't go into
> that here). You will plot one tile row too much on
> the right and bottom edge of
> the buffer.
> 
> Now, using (x1,y1), you copy the buffer onto the
> LCD, starting at row y1 in the
> buffer and shifting everything x1 steps to the left
> as you go. This part is
> basically how a sprite plotter works, but if you
> want speed you should write a
> routine that's specialized for this task.
> 
> 
>  / Niklas Brunlid
> Check out Prosit for the TI-89 / TI-92+ at
> http://prosit.ticalc.org
> Random PQF Quote follows:
> 
> When the least they could do to you was everything,
> then the most
> they could do to you suddenly held no terror.
>         -- (Terry Pratchett, Small Gods)
> 
> 
> 
> 


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