[racket] Doing collision detection in universe.ss

Right --- you don't want `#lang scratchy'. The `scratchy/runtime'
library might be useful.

At Wed, 28 Nov 2012 21:01:32 -0500, Yaron Minsky wrote:
> Ah, looking at scratchy more closely, I now think I understand it.
> It's neat, but it's not quite what I'm looking for.  In particular, I
> was looking for a set of libraries that made the kinds of things one
> can do in scratch easy to do.  But scratchy is its own little
> language, and doesn't give you access to lambda abstractions or other
> tools of the trade of Racket.
> 
> That said, the functionality is all there, so maybe I can bend it to
> my will somehow...
> 
> y
> 
> On Wed, Nov 28, 2012 at 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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