You're right about the timing. I'm fairly new to Smalltalk and had already hooked in a DLL for other things, so found it much easier to work matrix math in C :)
On Mon, Sep 22, 2008 at 7:58 PM, Matthias Berth < [EMAIL PROTECTED]> wrote: > Hi Iulian, > > I'm glad to hear that it worked for you. I wonder why you implemented > it in a C DLL... As far as I can see, the manipulations with the > parameters would be done only once for every quad you want to > transform. The computation time for that should be negligible compared > to the time it takes to actually transform all the pixels in the quad > / rectangle. At least that's what I was thinking, maybe i am wrong? > > Cheers > > Matthias > > On Tue, Sep 23, 2008 at 1:08 AM, Iulian Wande Radu > <[EMAIL PROTECTED]> wrote: > > Thank you for the guidelines for skewing forms. > > > > I've followed Matthias' instructions (and the associated math doc) and > > skewing works well this way through WarpBlt. (The code linked by Yoshiki > was > > too slow and didn't work fully). > > > > I wrote the math conversions in a C DLL, and it would probably be useful > for > > people. Is there any place where I could put the code so the community > can > > use it ? > > > > Cheers, > > Iulian > > > > ---------- Forwarded message ---------- > > From: Matthias Berth <[EMAIL PROTECTED]> > > Date: Tue, Jul 22, 2008 at 7:10 PM > > Subject: Re: [Newbies] Skewing Forms in Squeak V2 > > To: "A friendly place to get answers to even the most basic questions > about > > Squeak." <beginners@lists.squeakfoundation.org> > > > > > > So it comes down to this: > > > > given a projective transformation T from a rectangle (your form) to a > > quad Q (what you want to draw on screen), how can you express the same > > transformation in terms of mapping a quad to a rectangle (what WarpBlt > > needs)? > > > > One possible plan is: > > > > 1) determine the transformation's parameters > > > > 2) take the bounding box of Q (a rectangle R) and transform it by the > > inverse of T, giving you a quad Q' > > > > 3) use WarpBlt to transform pixels in Q' (should be a superset of your > > form) to R > > > > 4) mask the result with your original quad Q, using pixel-by-pixel > > operations on Forms > > > > I think all you need in terms of mathematics for this is in > > http://www.cs.cmu.edu/~ph/869/www/notes/proj/proj.pdf > > > > Hope this helps, feel free to ask about the details, > > > > Matthias > > > > > > > > > > On Thu, Jul 24, 2008 at 1:39 AM, Yoshiki Ohshima <[EMAIL PROTECTED]> > wrote: > >> > >> At Tue, 22 Jul 2008 13:53:21 -0400, > >> Iulian Wande Radu wrote: > >> > > >> > Hi, I'd like to skew the graphics of a Form, is there an easy way to > do > >> > this in v2 ? > >> > > >> > What I want is to take the rectangle from a normal form, transform it > >> > into an arbitrarily-defined quadrilateral, and > >> > then paint on the screen. I saw that WarpBlt does something like > this.. > >> > but it maps a quadrilateral section of a form > >> > onto a rectangle. > >> > >> There was similar a discussion on this a while ago: > >> > >> > >> > http://lists.squeakfoundation.org/pipermail/squeak-dev/2001-February/013402.html > >> > >> -- Yoshiki > >> _______________________________________________ > >> Beginners mailing list > >> Beginners@lists.squeakfoundation.org > >> http://lists.squeakfoundation.org/mailman/listinfo/beginners > > > > > > _______________________________________________ > > Beginners mailing list > > Beginners@lists.squeakfoundation.org > > http://lists.squeakfoundation.org/mailman/listinfo/beginners > > > > > _______________________________________________ > Beginners mailing list > Beginners@lists.squeakfoundation.org > http://lists.squeakfoundation.org/mailman/listinfo/beginners >
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