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18:20:39
scymtym
jackdaniel: the "patterns and designs" demo says if the y axis is flipped, DRAW-PATTERN* should draw the pattern within the flipped region (but without flipping the pattern itself, of course). do you know where the requirement to adjust the pattern position comes from?
20:41:15
jackdaniel
scymtym: my understanding of the spec is that draw-pattern* draws the pattern as a rectilinear rectangle filled with the pattern. since pattern is not a subject of the transformation, then it should always start at the top-left corner
20:46:26
scymtym
that would have to be based on the bounding box of the pattern since the shape of the pattern itself doesn't have to be an axis-aligned rectangle, right?
20:50:06
jackdaniel
afair if you do not call explicitly transform-region the pattern, then it always is axis-aligned rectangle; if you call transform-region, then hmm, I would need to think
21:13:37
jackdaniel
OK, so as I understand it, transform-region on the pattern transforms it (say, into a square rotated by pi/4)
21:15:07
jackdaniel
the medium transformation affects only the position of the transformed pattern (as in - we take into account only the translation)
21:16:22
jackdaniel
and to do that, we indeed take the bounding rectangle of the transformed rectangle (looking at the code)
1:25:23
scymtym_
jackdaniel: i was probably too tired to explain the problem but i tried anyway: https://techfak.de/~jmoringe/draw-pattern-1.ogv