[Squeakland] Pen Trails and Sensors

[Ned Konz]

On Friday 04 July 2003 10:56 am, Ned Konz wrote:
> On Friday 04 July 2003 11:15 am, Alan Kay wrote:
> > >Some context for the rest of the list: unless the Squeakland
> > > image has a fix that isn't in the Squeak 3.5 image, the turtle
> > > trails aren't visible in the color:sees: test.
> >
> > That's odd and interesting -- they used to be, and should be --
> > for just some of the reasons that Jeff needed them. There are
> > many wonderful things that can be done if the color sensing can
> > see the turtle trails. Any idea of how this got lost? Can Scott
> > Wallace easily put this back in?

It didn't really get lost. It just didn't work in the World (it did if 
you had an embedded playfield; perhaps that's what everyone does?).

> But there's two unresolved questions:
>
> 1. The turtle trails form is 8 bits. This means that the
> colorUnder: test may not work right when you're using a deeper
> Display depth. One possibility here (that will waste some memory)
> would be to make the turtle trails form as deep as the display.
> What should we do? Perhaps the deeper form should only be used when
> the preference is set?

My latest version only sets the turtle trails form to the display 
depth when you have the preference set to true. It's true by default, 
for backwards compatibility.

> 2. Should turtle trails also be visible to the #colorUnder test?

I posted another version that limits its scrutiny to the Morph's own 
pasteUpMorph/playfield (which would be the World, of course, if you 
aren't using an embedded playfield). This should speed up these tests 
as well.

-- 
Ned Konz
http://bike-nomad.com
GPG key ID: BEEA7EFE