Re: Apple II graphics

[CUTjefbla@bconnex.net (Jeff Blakeney)]

On 16 Jul 1998 04:55:55 GMT, supertimer@aol.com (Supertimer) wrote:

>Gabriel Morales <Togega@concentric.net> wrote:
>
>>Now I ask:
>>
>>Now, could I subsequently call up these graphics in BASIC in order to produce
>>simple animation, or is there a better way of doing this?
>
>Yes; the easiest way is to load up hires screens from the slot 3 RAM
>disk.  Assuming your program is in slot 6, drive 1 and your graphics
>are labeled gpx1 through gpx7, you can use the following program...
>
>10 let a=0
>20 let a=a+1
>30 ? chr$(4);"bload gpx";a;",s6,d1"
>40 ? chr$(4);"bsave gpx";a;",a$2000,l$4000,s3,d2"
>50 if a=7 then goto 70
>60 goto 20
>70 hgr
>80 let b=0
>90 let b=b+1
>100 ? chr$(4);"bload gpx";b;",s3,d2"
>110 if b=7 then goto 80
>120 goto 90
>130 end
>
>The reason you want to load from s3,d2 is because of the speed
>of the RAM disk.  If you have a larger RAM disk, you can add more
>frames.
>
>My Applesoft BASIC is VERY rusty, so someone please check my
>program...I am especially not sure about a$2000,l$4000...

That should be A$2000,L$1FF8 for a single hires image in hires page 1.
For hi-res page 2 you would use A$4000,L$1FF8.  You can use L$2000 if
you want but it will use an extra block on the disk that doesn't
contain any image data.

The above program (lines 80-130 are all that would be needed) could
also be used from a hard drive but the frame rate wouldn't be as good.

However, I believe there was a suggestion to use Double Hi-Res
graphics which makes things a little more difficult because DHR
graphics use twice as much drive space.  This means it will take twice
as long to load the image from disk and it will also take longer to
display because you need to load one hi-res page, move it into Aux
memory then load the second hi-res page and display the DHR screen.
Also, there is no page 2 for DHR graphics so you can't load the second
image into page two, display it, then load the next image into page 1,
display and so on.

There are a lot of things to consider when doing any sort of animation
on an Apple II so if Gabriel Morales (any relation to Tony Morales?)
could be more specific about what they are trying to do, we should be
able to help more.

=== I've had enough SPAM.  Cut the obvious from my address to email me. ===
         Jeff Blakeney - Dean of the Apple II University on Delphi