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free-style "usesrcdim" mode on a matrix , sort of reversed cornerpin

Feb 20 2014 | 3:26 am

hi everybody ,
i thought i could get it ,but still can’t find a way…

i would like to resize an image in a matrix ,
as if i was using "srcdimstart" and "srcdimend" ,
but ,

the difference is that i would like not to be constrained by 90 degrees angles , at all .

i would like to be able to point any location in the matrix , and link it to one of the corners of my new matrix (which will be a rectangle , but with extrapolated pixels from the 4 corners –> the new """"texture coordinates"""")
and do the same for the 3 other points (as if i was using a sort of reversed cornerpin ) .

i’m not sure i’m clear , …
i want my matrix to keep the same dimensions ,
but its pixels to be extrapolated from new coordinates ,
inside this same matrix .

that will add duplicate pixels in the matrix , and that’ s what i’m looking for .

mxform2d and jit.repos seem to be , maybe , the good boxes ,
but i would like a click and drag-style method .

i have put a to point on a gl context ,
(i get the coordinates with "getstate") and a videoplane which exactly fits the window’s borders ,
the normalized coordinates of the cornerpin’s corners is then scaled to the window’s resolution , giving me the x and y coordinates in the image .

so that i should get the exactly same image , inside the , and on the videoplane ,
wherever i would move the corners ,
IIIIIIFFFFFF , i had the answer to my question ,
which is not the case .

here is a patch

-- Pasted Max Patch, click to expand. --


am i clear enough ?
still not sure …


Feb 20 2014 | 8:55 am

mmm , i wasn’ t very clear , i think .

i also think one possibility is jit.repos .
i would have to send its first inlet the "full" matrix ,
and the right inlet a matrix with 2 planes .

#first plane
-first row would go from top_left cornerpin x scaled value to top_right cornerpin x scaled value .
-last row would go from lower_left cornerpin x scaled value to lower_right x scaled value .
all the rows between , would have to interpolate between these two rows ,

#second plane
exactly the same , replacing "x" with "y" , and "vertically" with "horizontally"

if , by any chance , i’ m saying something that can work ,
would anybody lead me to the right jit.expr formula to achieve this ?
the one that will , with 4 pairs of coordinates , create the magic matrix !

here is another patch ,
nearly the same as the previous one ,
but this one goes far beyond the end of my jit.expr universe .

anyway , have fun

-- Pasted Max Patch, click to expand. --



Feb 20 2014 | 9:07 am

mmm ,
maybe i should better directly use the normalized coordinates , without scaling ,
and work with float32 matrix ,and then convert to char matrix just before jit.repos …

-- Pasted Max Patch, click to expand. --


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Forums > MaxMSP