Water Effect (C64)

On the Commodore 64 one could manipulate a VIC register for horizontal scrolling up to one character position. This becomes more interesting when it is turned into a background interrupt that is timed to raster lines to break up the vertical field.

Category:

Science & Technology

Tags:

• C64
• interrupt
• programming
• assembly
• 6510
• ML

[Kaonashi5]

This is over 20 years old. The only thing new is the video capture.

Bear in mind that that is a live cursor at the end. You could be working on other stuff while this is running in the background, though I imagine it could make you sick.

[jeffthecoder]

@Kaonashi5 u cant fool me, tho, i wrote a similar interrupt routine to make the border fade different shades of colors (well, sort of) while you were free in "ready mode"..as soon as you type "list" and the screen starts scrolling it gets crazy slow..

[Kaonashi5]

@jeffthecoder Sure it would get slow. This is the BASIC interpreter doing the text scrolling which should be relatively expensive in CPU cycles. I forget whether this water effect sets the next interrupt to start in 8 raster lines (8 vertical pixels) -- for 24 or more interrupts per screen refresh -- or if it just timed over the visible field. The former would be more efficient, but for cleaner screen effects you have to have absolute control of what's happening around the raster line.

[lukeskywalker7878]

I typed all of that but it says:

?out of data error in 20

in line 20 i put:

20 READ D:POKE I,D

whats the problem?

[Kaonashi5]

@lukeskywalker7878

Out of data means just that. It ran out of numbers. One of the lines of data is missing or incorrect. You'll have to proofread what you entered. There are 124 numbers, no less.

[cobrachoppergirl]

Lol, I remember doing tins like this, by shifting the screen one bit left or right.

[AMYuntold]

@jeffthecoder Another World is a Mega Drive classic for me... :-)

[jeffthecoder]

@AMYuntold id say no, they have c-64 indie game comps all the time..reverse engineer the c-64 game "prince of persia" and remake the snes classic "another world", ya?

[chrisheilmann]

@Okarter yes it was

[chrisheilmann]

D016 pushing. Ahh... long time ago

[Okarter]

Wasn't that called a tech-tech back in the day?

[sapiigor]

MAN i remember doing this shit back in 80's - 90's couldnt dream that my phone gunna have 1 000 000x faster processor or more memmory...

[adisharr]

@KillinDaWelfareMCs If you need an explanation then you should move on.