Squeak-dev August 2000

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130 participants
418 discussions

Re: Learning B3D (newbie)
by Jesse Welton 02 Aug '00

02 Aug '00

I also had a couple of questions about the B3D engine. In my experimenting, I've been putting a B3DSceneObject with a B3DSimpleMesh into a B3DSceneMorph. I eventually figured out how to use the texCoords to texturize the model, and color the whole thing with a B3DMaterial with an appropriate emission color. What's stumping me, though, is how B3D works with translucency. I'd really like to be able to use translucent 3D objects, and B3DMaterial and B3DMaterialColor support some kind of alpha channel, but it doesn't do anything for my models. So, two questions: Can I do what I want? (And even if I can't) Where should I look to start understanding translucency and lighting? -Jesse

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Learning B3D (newbie)
by aldel＠alum.mit.edu 02 Aug '00

02 Aug '00

I've been trying to figure out how to do 3D rendering (and simultaneously learning Smalltalk and Squeak, but I'm doing OK with those). The examples in the Balloon3D-Demo Morphs category make some sense, but when I try to do my own rendering, I get nothing. In particular, the following code typed in a workspace just makes a black square (from the clearViewport message): rend _ B3DRenderEngine defaultForPlatformOn: Display. rend viewport: (Rectangle origin: 10@10 extent: 200@200). rend clearViewport: Color black. cam _ B3DCamera new. cam initialize. cam position: 0@0@2. rend clearDepthBuffer. rend loadIdentity. cam renderOn: rend. "tex _ Form fromUser. rend texture: tex." "rend trackEmissionColor: true." rend normal: 0@0@1. rend color: Color white. rend drawPolygonAfter: [ rend "texCoords: -1@-1;" vertex: -1@-1@0; "texCoords:1@-1;" vertex: 1@-1@0; "texCoords: 1@1;" vertex: 1@1@0; "texCoords: -1@1;" vertex: -1@1@0. ]. The lines that are commented out are things that I tried but didn't help. Can anyone explain what I need to to differently? Once I've got that figured out, obviously I'll be wanting to do more. Is there any documentation outside of the code? Barring that, an example that's more interesting than an unshaded rotating cube but less complicated than Alice would be useful. A couple specific questions: Is there an easy way to make it render wireframes? (Something like OpenGL's glPolygonMode(GL_FRONT,GL_LINE)) A way to cull back-facing polygons? (Like glCullFace(GL_BACK)) What's the status of the hardware rendering plugin? Will code I write now have to be changed to take advantage of it? Alan deLespinasse

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unsubscribe
by john.g.gardner＠ca.pwcglobal.com 02 Aug '00

02 Aug '00

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Polymorphism and language
by Adam Bridge 02 Aug '00

02 Aug '00

I wonder if we're not asking the wrong question here. Language, it seems to me, is for expression. If we design a language (as opposed to allowing it to evolve) then we should have a goal for that language. What's the goal here? Although polymorphism is certainly an interesting capability shouldn't we be looking at the kinds of tasks we wish to perform? Would we demand an artist work in tempra when water color is what expresses the mood best? Personally I like the idea of small languages that do some things very very well. They are easy to learn because their concepts are clear. If languages can agree on ways to intermingle so I can write my image manipulation in one language and my text in another and my GUI in yet another -- and have them work together intimately and EASILY -- then I think we have a software system which is about expression first and language second. I'd love to easily, trivially, combine Smalltalk, Perl, Fortran, Obj-C and be able to easily explore other languages in this same context: it becomes easy to grow. Adam Bridge

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Re: [Q] Does anyone have a radix searchtrieSmalltalkimplementation?
by Roel Wuyts 02 Aug '00

02 Aug '00

Unification is a two-way, generalized form of pattern matching between two terms. If you have two terms (say A and B), and an environemt E, then unifying A and B means comparing A and B (filling in the results in the environment) in such a way that, after unification, substituting what was found in A and B shoud give an equal term. I think it originated in logic programming, so I'll give some examples to clarify this explanation (I use Smalltalk comments, and variables are denoted with question marks): 1. A = ?var "a variable", B = john "a constant" E = [] "an empty environment" unifying A and B will give an environment E = [?var -> john], where ?var is bound to john. substituting the environment E in A yields: john. substituting the environment E in B also yiels: john. 2. A = foo(bar, fi(john)) B = foo(?one, fi(?two)) E = [] will yield E = [?one -> bar,?two->john] 3. A = foo(?one, fi(john)) B = foo(bar, fo(?two)) will yield the same as above. Note however that the pattern matching happens in two ways: bindings for variables are found in such a way as to making the terms equal after substitution, regardless where they occur. More information about unification (including algorythms) can be found in most Logic Programming or Prolog books. Since I implemented a logic programming languages, we implemented some of these (which is simple to do). >>Thanks, Mark. I'll dig into it. Perhaps there will be something about >>unification. I've never heard of that term before. > > I'll attempt a definition: Unification is the process of mapping two > forms (e.g., equations) onto one another such that variables (in the > form) are set to appropriate values and constraints are maintained. > The process may involve backtracking, and can also end in failure (if > no match is possible). > > I did some web-hunting and this page seems like a reasonable intro to > unification: > > http://www.ccs.neu.edu/home/arthur/unif.html > > I first learned about it reading Patrick Winston's first book on Lisp > -- I remember typing in the code and poking at it forever trying to > figure out how it was working. I think that the best description of > the algorithm, though, is in Brian Harvey's "Computer Science Logo > Style" series (Volume 3, I think). (In general, next to "Structure > and Interpretation of Computer Programs," Harvey's books are my > favorite CS texts.) > > Mark > > -------------------------- > Mark Guzdial : Georgia Tech : College of Computing : Atlanta, GA 30332-0280 > Associate Professor - Learning Sciences & Technologies. > Collaborative Software Lab - http://coweb.cc.gatech.edu/csl/ > (404) 894-5618 : Fax (404) 894-0673 : guzdial(a)cc.gatech.edu > http://www.cc.gatech.edu/gvu/people/Faculty/Mark.Guzdial.html > -- Roel Wuyts Programming Technology Lab rwuyts(a)vub.ac.be Vrije Universiteit Brussel http://prog.vub.ac.be/~rwuyts Webmaster of European Smalltalk User Group: www.esug.org

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Re: slimming the image
by Roel Wuyts 02 Aug '00

02 Aug '00

>> A counter-example is Emacs. Emacs has *tons* of code available for it, >> and yet it all tends to work nicely together with any subset of the >> modules loaded. And Emacs doesn't even have namespaces! It's all done >> by hand. >> >> I don't know why it works out, but it certainly does, somehow or another. >> It's at least *possible*. > > The reason why Emacs handles the complexity (module > dependency) better might be partly because the presense of > "built-in" mechanism, such as require/featurep/autoload: the > submodules declare which module depends on which with those > mechanism. > > It would be nice if the user can declare the module > dependency in class definition or in class-category, and > those declarations are included fileouts. > > However, Emacs also suffers from the same problem, IMO. > For example, the independent minor-modes tend to conflict in > keymaps and something like that. > > -- Yoshiki (at Pacific Time) > I strongly believe that some form of modules/typing/aspects/... is closely related to the issue of slimming the image (and being able to do so in a repeatable, (semi-) automatic way). One way to start this could therefore simply be to define some 'core' pieces of code, and start documenting these. Since several people started doing this (but, I guess stopped, since this is hard work to do by yourself), it should be possible to make a Swiki-site where we can start drawing boundaries. The next step would be to document these classes, for example simply by putting in the class comment the name of their module first, and then the rest of the module. This is just a ferst step, and perfectly doable in a current system. Once it is done, a simple enumerator could already fetch all the classes in the modules (because we categorized them by hand). The next step would be something to make this better structured, extensible and processable. Maybe some stuff is already out there. Or maybe Mat's rework of the parsetree and the compiler will help. We could, for example, add comment in a specific format that could be retrieved as module descrition, and simply enumerate this. This would also allow the finer grained categorization (e.g. also methods, instance variables, in the limit individual statements!), since this is just a node in the parsetree. At the ends of these steps, you would have some system that, once it is tagged manually, can be used to support slimming the image. Then comes the more fancy stuff that interests me (and some of my colleagues in the lab) a lot: helping with the categorization. For example, when the complete Collection hierarchy, except some classes, should be in a module, it would be nice to just say so in a tool, that would do the appropriate stuff (adding comments, updating parsetrees, ...). Or typing the instance variables to help finding relations between classes (I use a lightweight typing scheme to support this in my logic language, and it gives remarkable results). Or... or ... or ... And of course there are intersection with this and the actual storing of source code too. But I guess some people know much more of this then I do... -- Roel Wuyts Programming Technology Lab rwuyts(a)vub.ac.be Vrije Universiteit Brussel http://prog.vub.ac.be/~rwuyts Webmaster of European Smalltalk User Group: www.esug.org

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Mouse enter/leave "bug"
by Gargus, Joshua -ND 02 Aug '00

02 Aug '00

Hi Morphic hackers, Currently, a morph (aMorph) has no way of being notified when a the cursor leaves one of its submorphs but stays within aMorph. There have been several instances when I've wished that a #mouseEnter event was generated and sent to aMorph, and I am unable to think of a situation where the current behavior would be preferred. I traced the problem to two methods in HandMorph, #handleDragOver: and #handleMouseOver:. I've attached a changeset that attempts to fix the problem, but fails miserably. One reason is that sometimes the cursor has moved onto another submorph of aMorph, and the event that I cause to be generated to aMorph trounces the one sent to the submorph. I can imagine going through the #mouseEnter list to get rid of morphs whose submorphs also appear in the list, but: 1. I don't know if this would solve the problem 2. That seems like an excessively expensive bit of code to put into the event loop Does anyone else have any insights? Thanks, <<MouseLeaveAndEnterFixes.2.cs.gz>> Joshua

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Re: modelling program comments
by Les Tyrrell 01 Aug '00

01 Aug '00

I like Lex's suggestion, but would reccomend that it be constructed along lines where at some future date one could attach arbitrary "metadata" ( objects ) to some reasonable set of program structures, not only within the methods but at higher levels as well. Basically, I am asking only that you don't build into such code the notion that we are only dealing with text- let it be something a bit more abstract, so that we are not limited in the future to strictly textual commentary. - les

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Re: 4th Estate server (roarr.com) - gone
by Paul McDonough 01 Aug '00

01 Aug '00

Thanks! I'll get in touch offline. It will be about a week, at least, until we can get the code sorted out and reorganized for posting. Cheers, Paul --- Roel Wuyts <rwuyts(a)vub.ac.be> wrote: > Do you need a server to put them on ? Since we are > already serving Smalltalk > User Group related sites, we could take one more :) > > > Fellow Squeakers: > > > > As a few of you have noted offline, the 4th Estate > ftp > > server where we stored our Squeak contributions > for > > download is no longer there. That is because, > quite > > literally, it is no longer there, and we don't > > expect it to come back. > > > > The projects will be reappearing shortly, although > > exactly when/where is still unclear. Please feel > free > > to contact me offline and I will be happy to > discuss > > the status of each. All of them require some > clean-up > > before any but the most cussed and determined > > Squeakers will want to try to install them (see > > previous discussions on this list). That clean-up > is > > in progress. > > > > The projects are: > > > > - port of T-Gen to Squeak > > - a project related to platform events (as yet > > nameless) > > - a versioning doo-dah, which you may have heard > > referred to as > > "Roarr" > > - a platform level messaging channel (nameless? - > I > > forget) > > > > I will post updates as these projects become > available > > for download. Please note that while the code is > open > > source under the Squeak license, the name "Roarr" > is a > > trademark of 4th Estate, and that project when it > > reappears will be known as "Tefkar". Well, why > not > > "Tefkar"? > > > > On behalf of the ex-4th Estate Squeakers, > > Paul > > > > wnchips(a)home.com > > > > __________________________________________________ > > Do You Yahoo!? > > Kick off your party with Yahoo! Invites. > > http://invites.yahoo.com/ > > > > > -- > Roel Wuyts Programming Technology > Lab > rwuyts(a)vub.ac.be Vrije Universiteit > Brussel > http://prog.vub.ac.be/~rwuyts > Webmaster of European Smalltalk User Group: > www.esug.org > __________________________________________________ Do You Yahoo!? Kick off your party with Yahoo! Invites. http://invites.yahoo.com/

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status of WinCE port of 2.8/2.9?
by Ned Konz 01 Aug '00

01 Aug '00

The most recent WinCE work I've seen is the 2.7build8 stuff. Has anyone touched it since then? Andreas? I was going to have a go at it to try to improve the speed, but don't want to duplicate anyone's work. -- Ned Konz currently: Stanwood, WA email: ned(a)bike-nomad.com homepage: http://bike-nomad.com

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