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 Tue, Jul 22, 2008 at 9:31 PM, Iulian Wande Radu infinite.flow@gmail.com wrote:
Back to the question... Yes WarpBlt is available in v2, but I can't seem to be able to use it for this purpose, because it maps a quad to a rectangle (not a rectangle to a quad). There must be a way to do this...
On Tue, Jul 22, 2008 at 3:27 PM, Brad Fuller bradallenfuller@gmail.com wrote:
what is Squeak V2?
On Tue, Jul 22, 2008 at 12:02 PM, Matthias Berth matthias.berth@googlemail.com wrote:
Hi,
is WarpBlt available in Squeak V2?
On Tue, Jul 22, 2008 at 7:53 PM, Iulian Wande Radu infinite.flow@gmail.com 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.
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