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+---- Thread: scroll.bas (/showthread.php?tid=415)
scroll.bas - britlion - 2011-12-07
Was thinking of doing some scroll routines. I see there are some useful ones in scroll.bas in the library.
However, there appears to be a left, right and another left in there - no up and down!
sub fastcall ScrollRight
sub fastcall ScrollLeft
sub fastcall ScrollLeft
two also begin a bit strangely - loading the byte at (screenaddress) twice?
Re: scroll.bas - britlion - 2012-08-04
*bump*
Are these okay? Do we need replacements?
Re: scroll.bas - slenkar - 2012-08-04
I have never used scroll, so dunno how they act under gaming conditions
Re: scroll.bas - boriel - 2012-08-05
Not sure how you got them. They should not be bundled with the compiler.
I stop programming them, to address more important issues.
Horizontal scroll is pixel by pixel.
I can finish scroll (and roll) in the 4 directions (Up, Down, Left, Right). But pixel by pixel scroll is slow.
A better routine would be:
- Scroll within a given window (e.g. x, y, height, width)
- Scroll the given amount of pixels. This is more interesting, but I guess it's much harder when done horizontally.
- Scroll colors (attributes)
Re: scroll.bas - britlion - 2012-08-05
Window scroll up is already in wiki library. Scroll down would be a trivial alteration from that.
Left and right is a matter of using 9 bit rotates to carry to next byte - for a single pixel. More than one pixel is a bit tougher to do.
Re: scroll.bas - boriel - 2012-08-05
I recall there's already a SC/ROLL (Roll means exiting pixels reenter the opposite side) in a MicroHobby machine listing.
I think I could rip them from there.
Re: scroll.bas - slenkar - 2016-04-25
what do the four numbers represent?
Cant figure it out!!
Whenever I make changes to the numbers the results make no sense
If I change the first 2 numbers to zero the same scroll happens at 40,40
then other numbers when increased make the window smaller!
Re: scroll.bas - britlion - 2016-05-03
You mean <!-- m --><a class="postlink" href="http://www.boriel.com/wiki/en/index.php/ZX_BASIC:WindowScrollUp">http://www.boriel.com/wiki/en/index.php ... owScrollUp</a><!-- m --> ?
Unless it broke somewhere, and I remember correctly (it's been years); X and Y should be the top left corner, and the other two numbers are the width and height of the window.
Re: scroll.bas - slenkar - 2016-05-30
It's in the demo folder of the latest release
The demo prints a bunch of letters to the screen, then they are scrolled in all directions
Re: scroll.bas - slenkar - 2017-01-01
The numbers dont seem to behave as I would expect, can someone take a look?