A86: Re: Re: Re: ASM Clear-Up
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A86: Re: Re: Re: ASM Clear-Up
>
>Thanks for the help and again, I'm sorry about the HTML messages. Why not?
>
HTML just annoys some people because their mailer doesn't support it (I hate
it because I have to add the '>' things by hand). Don't worry about. But
going for everyone, make sure you set the default outgoing messages to TEXT
not HTML, please.
>When you use this routine you can change the value that is loaded into the
>bc register right? But if you do it will screw up the clipping and masking
>though. Thanks for the help again. I'm starting to understand a whole lot
>more things tonight.
Change the value? Of course! That's the point, FindPixel finds the address
of the pixel location (b, c) as if they were (x, y) coordinates (0..127,
0..63). I don't understand what you mean by "screw up the clipping and
masking". This is a FindPixel routine, all it does is return the address in
HL and the mask in A. If you pass it bogus coordinates, then you will get a
bogus address.
Clipping and masking are features that a sprite routine would have. A
findpixel routine is sometimes used by sprite routines, but when I wrote
mine I used a FindAddress routine that return the offset (offset of the byte
in a buffer, not $fc00) and the offset of the byte in C (how many times
you'd have to shift the bytes).
Btw, if anyone has any clipped-masked sprite routines that render the sprite
using bytes and not bits (meaning it doesn't loop for each pixel), I'd love
to see them!
--
David Phillips <david@acz.org>
http://www.acz.org/