Re: A86: Major Problem with FindPixel

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Re: A86: Major Problem with FindPixel


I see how it works,

B is loaded with the mask from FindPixel
A is loaded with the current mask from the video display

then you OR them.

So you could change the OR to XOR and get an XORing pixel routine?  cool :)

(If you haven't guessed, this is my very first attempt at writing a game
<grin>)

Is this the fastest way to plot a pixel?

At 06:01 PM 4/7/98 -0700, you wrote:
>
>yeah do this:
>
>ld d,1
>ld e,3
>call FindPixel
>ld (hl),a
>ld d,1
>ld e,4
>call FindPixel
>ld b,a
>ld a,(hl)
>or b
>ld (hl),a
>
>that will work.. FindPixel was NOT designed to do what you described.
It's not a 'major problem'  It was developed to ruturn hl with the base
memory and A as
>a mask showing where the 'true' posistion is..
>
>
>Ricci E. Adams wrote:
>
>> Has anybody notice while using FindPixel that if you put 2 pixels with the
>> same Y value next to each other the second one will erase the first one?  I
>> am using the following routine:
>>
>> ld d,(ter_y)
>> ld e,(ter_x)
>> call FindPixel
>> ld (hl),a
>>
>> This is probobly caused by the first pixel having an A value of %01000000
>> (or close to it) and the second having an A value of %00000100 (or close to
>> it).  The second A value completly erases the first pixel.  The solution
>> would be to have the FindPixel routine retern %01000100 instead of
>> %00000100 the second time.  Does anybody have a clue how to do this?
>>
>> I need this for the terrain routine for my game.  Right now, the calculator
>> choses +1, 0, or -1 and adds it to the current Y value, the X value is
>> continually increased cause random smooth terrain to form.  The problem is
>> whenever the calc choses 0, it erases all the neighboring pixels on the
>> same level due to the problem stated above.
>>
>>
>>
                                                               -Thanks
>>
                                                               Ricci Adams
>>

ricci@chipsnet.com
>
>
>
>--
>Trent Lillehaugen
>Computer Engineering Major
>California Polytechnic University, San Luis Obispo
><http://www.calpoly.edu/~tllilleh/a86/a86.html>
><mailto:tllilleh@polymail.calpoly.edu>
>
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