Animate bug. Zero crossing.

[ewgeniktomsk]

We are trying to move the text vertically. From y=10 to y=-10. When passing through 0 text appears in the center of the screen.

BlankClip(length=50, width=72, height=40)
	Animate(0,50,"Subtitle", \
	"Text1\nText2",36,10,0,50,"Arial",24,$FFFF00,0,5,0,-1, \
	"Text1\nText2",36,-10,0,50,"Arial",24,$FFFF00,0,5,0,-1)

Tested on AviSynth 2.60, AviSynth+ 3.7.2

[pinterf]

Thanks for the report, in rest of July I'm on PC-less holiday, I can check the issue later.

[qyot27]

Quasi-related, is that on Linux that example script will cause a segfault because a font that's not available is specified. Changing it to the internal Terminus font* resolves it.

*which, obviously, is the only one available on *nix, because we don't use fontconfig or Core Text for looking up fonts. It would probably also segfault on Windows in builds where GDI is turned off.

Unfortunately, I'm not seeing this bug happen on Ubuntu, even once I massaged it enough to actually see the Text1 line by adjusting the start position to 25 (which is pretty close to the gif provided by OP), and then even more dramatically to 50 (with Text1 almost at the bottom of the frame, so you can see both it and Text2 scroll past the 0 line). In both cases, it scrolled past 0 and didn't flash back to Text1 again.

[ewgeniktomsk]

I will not be too lazy to install Ubuntu and check. I'll let you know the result.
By the way, the problem appears only at a slow text speed. Apparently, at high speed, the text simply skips the fatal mark. So in order to get a bug, the start and end positions should be closer to 0.

[pinterf]

Reproduced. Subtitle - when y=-1 is passed (which is reached at frame 28 during Animate 10->-10 interpolation) - has a special internal meaning, which prevents using this exact y coordinate. Fix is in progress.

[pinterf]

Quasi-related, is that on Linux that example script will cause a segfault because a font that's not available is specified. Changing it to the internal Terminus font* resolves it.

This bug is found as well.