[racket] Doing collision detection in universe.ss

This sounds ideal.  I'll check it out.
On Nov 28, 2012 8:00 AM, "Matthew Flatt" <mflatt at cs.utah.edu> wrote:

> For what it's worth
>
>  https://github.com/mflatt/scratchy
>
> is an implementation of the Scratch sprite and evaluation model plus a
> textual language. It has all of the drawbacks of Scratch --- mutation,
> race conditions, and busy waiting --- without the nice graphical
> syntax! It has a collision detector that's much like John's, but I
> spent some time making it go faster. There's also a notion of "lands"
> within a program.
>
> I wrote Scratchy as an example of building languages in Racket for this
> year's RacketCon.[*] I dream about a phase 2 where I figure out how to
> change the evaluation model to something good and/or connect with
> `2htdp/universe', but I don't see that happening soon.
>
> [*] At the suggestion of my son. He's a Scratch fan, though he quickly
>     became frustrated by the lack of abstraction in Scratch, and I
>     don't know whether to be happy or sad that he's a 12-year-old who
>     understands the phrase "race condition". Scratchy has "lands" because
>     he wanted something like that for his game.
>
> At Wed, 28 Nov 2012 07:37:27 -0500, Yaron Minsky wrote:
> > To be clear, I'm firmly interested in tinkering, which is why I'm
> > using universe.ss and image.ss.
> >
> > I do think that a good design goal for Racket's kid-oriented libraries
> > would be to be feature compatible with Scratch.  It would be great if
> > there were good ways of doing everything that Scratch can do, from
> > playing sounds to detecting collisions, to (more aggressively) on-line
> > hosting of the final result.  I'd love it if Racket were strictly
> > better than Scratch for someone who really can figure out how to
> > program, but it's just not true now.
> >
> > y
> >
> > On Wed, Nov 28, 2012 at 7:11 AM, Hendrik Boom <hendrik at topoi.pooq.com>
> wrote:
> > > On Tue, Nov 27, 2012 at 08:56:13PM -0500, Yaron Minsky wrote:
> > >> I've been weaning my son off of Scratch in favor of Racket, and trying
> > >> to get him to write interactive games using universe.ss and image.ss.
> > >> I'm wondering if anyone has suggestions for how to do things like
> > >> collision detection.  image.ss has these nice first-class images, but
> > >> I don't see a good way of querying two images to see if they overlap.
> > >>
> > >> Has anyone else had luck in doing this?  universe has a nice
> > >> programming model, but I've found it challenging to find simple ways
> > >> of doing the kinds of things that Scratch makes easy.
> > >
> > > There are two arts to collision detection: figuring out whether two
> > > images collide (which gets trickier when they're in motion) and
> > > organising all your objects so you don't have to test very many
> > > combinations of them.
> > >
> > > Both of these can get quite complicated, and are susceptible to
> > > nontrivial, complicated, and often necessary efficiency improvements
> > > depending on special properties of the game.
> > >
> > > A one-size-fits-all solution may be good enough for tinkering with, but
> > > serious use may well need serious hacking.
> > >
> > > -- hendrik
> > > ____________________
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>
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