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Changes between Initial Version and Version 1 of Ticket #2649, comment 3

initial	v1
1		Consider the result of r.drain, which is an already-thinned line of pixel centres, obviously in "runs" of x,y moving +/- 1 in x and/or y. We'd like for the runs be "collapsed" into only the corners where the direction changes. Further, we'd like that running the stream on another grid respect that we also need the corners where the color or value on the resulting line changes. The segments will be given the color of the pixel under the second of every pair.
	1	Consider the result of r.drain, which is an already-thinned line of pixel centers, obviously in "runs" of x,y moving +/- 1 in x and/or y. We'd like for the runs be "collapsed" into only the corners where the direction changes. Further, we'd like that running the stream on another grid respect that we also need the corners where the color or value on the resulting line changes. The segments will be given the color of the pixel under the second of every pair.
2	2	r.to.vect already handles these runs when they are straight in the x or y, but not in diagonals where both x and y change.
3	3	The attached before/after screen shots show where this has become a visible defect.