Re: A89: Re: Re: Survey for the next version of PlusShell


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Re: A89: Re: Re: Survey for the next version of PlusShell




At 04:28 1998-11-19 -0500, you wrote:
>Let me revise that: there are actually three cases, the third being that
>_both_ coordinates are of negative values.  In some clipping routines, this
>must be treated as a unique case. 

Then the clipping routine was bad...

>(Really; before I implemented that case
>in the 89 clipping routine I wrote, it actually crashed the calc when you
>tried to move the sprite off both the top and the left edges of the screen
>simultaneously) This is very nice because on all other TI calcs there are
>eight cases you must implement! (or at least test)

No, only 4 cases. In ASCR (sprite clipping for the 86), it's only
four cases. For left & right, I create a mask. If x=-2, the
mask would be %00111111 (8 bit sprites on the 86), if x=MAX_X-3,
mask = %11111000. For top & bottom, just start on a different row,
and change number of rows to put.
 
//Jimmy Mårdell

E-mail: yarin@acc.umu.se
Homepage: http://www.acc.umu.se/~yarin/


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