# help drawing a polygon using drawPolygon

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## help drawing a polygon using drawPolygon

 Hello,I've been looking at the documentation for a while and I can't figure out what I'm doing wrong. There doesn't seem to be an example to help guide a beginner in this process and the terms aren't exactly clear.I'm trying to draw a triangle with the coordinates (-1, -2), (0, -2), and (1, -2). The documentation for drawPolygon suggests it can take a list of coordinates or some type of array, but I can't find any examples or explanations for how the data should be entered and nothing I've tried has worked.drawPolygon(COORD) - what does it mean to 'pack' coords into a single array? How does one accomplish this?drawPolygon(PX, PY) - how do you specify the coordinates in different arrays? I tried passing in [-1 -2], [0 2], [1 -2] as well as [-1; -2], [0; 2], [1; -2] to no avail.drawPolygon(POLYS) - I looked up cell arrays, but none of the notation I've tried has worked here.My goal is to draw a triangle at the given coordinates and then draw it again on the same plot using a different color after applying a linear transformation to rotate it. Any help or guidance anyone can offer would be greatly appreciated.Thanks,Tony _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave
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## Re: help drawing a polygon using drawPolygon

 On Tue, Feb 21, 2017 at 7:47 AM, Anthony Andriano <[hidden email]> wrote: > Hello, > > I've been looking at the documentation for a while and I can't figure out > what I'm doing wrong. There doesn't seem to be an example to help guide a > beginner in this process and the terms aren't exactly clear. > > I'm trying to draw a triangle with the coordinates (-1, -2), (0, -2), and > (1, -2). The documentation for drawPolygon suggests it can take a list of > coordinates or some type of array, but I can't find any examples or > explanations for how the data should be entered and nothing I've tried has > worked. > > drawPolygon(COORD) - what does it mean to 'pack' coords into a single array? > How does one accomplish this? > > drawPolygon(PX, PY) - how do you specify the coordinates in different > arrays? I tried passing in [-1 -2], [0 2], [1 -2] as well as [-1; -2], [0; > 2], [1; -2] to no avail. > > drawPolygon(POLYS) - I looked up cell arrays, but none of the notation I've > tried has worked here. > > My goal is to draw a triangle at the given coordinates and then draw it > again on the same plot using a different color after applying a linear > transformation to rotate it. Any help or guidance anyone can offer would be > greatly appreciated. > > Thanks, > Tony > > _______________________________________________ > Help-octave mailing list > [hidden email] > https://lists.gnu.org/mailman/listinfo/help-octave> Hi Anthony, I can't check right now, but my guess is, for the second way to call drawPolygon, PX stands for the x coordinates of your polygon, and PY stands for the y coordinates of the polygon, so, try something like: PX = [-1 0 1]; PY = [-2 2 -2]; drawPolygon(PX, PY); Hope this helps. James Sherman _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave
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## Re: help drawing a polygon using drawPolygon

 In reply to this post by Anthony Andriano On Tue, Feb 21, 2017 at 7:47 AM, Anthony Andriano <[hidden email]> wrote: > Hello, > > I've been looking at the documentation for a while and I can't figure out > what I'm doing wrong. There doesn't seem to be an example to help guide a > beginner in this process and the terms aren't exactly clear. It seems there could be some improvements to the documentation here to make things a bit more clear. It appears most of the description to help you answer those questions is hiding in the "See also: polygons2d" so >> help polygons2d or simply >> polygons2d will give you the help text describing a good part of the required usage info for polyline and polygon functions in this package. in short: (note your points are only a line, with all y = -2. I've change the 2nd point to [0,2] to make a triangle) COORD = [-1, -2; 0, 2; 1, -2]; drawPolygon(COORD); also: close all; PX = [-1 0 1]; PY = [-2 2 -2]; drawPolygon(PX,PY); gives me the points [1 -2], [2 2], and [3 -2].  not sure why. but making the PX and PY column vectors works: close all; PX = [-1 0 1]'; PY = [-2 2 -2]'; drawPolygon(PX,PY); For the last one, the polygons2d text indicates that multiple polygons can be included in a single COORD array using a [NaN, NaN] line as the separator, but the text for drawPolygon(POLYS) indicates that POLYS should be individual polygon coordinate sets in a cell array. Trying: COORD = [-1, -2; 0, 2; 1, -2; NaN, NaN; 5 0; 6 1; 7 0;]; drawPolygon(COORD); gives me two triangles as expected. close all; POLYS = {[-1, -2; 0, 2; 1, -2], [5, 0;6, 1;7, 0]}; drawPolygon(POLYS); Produces the same output. _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave
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## Re: help drawing a polygon using drawPolygon

 In reply to this post by Anthony Andriano On Tue, Feb 21, 2017 at 7:47 AM, Anthony Andriano wrote:Hello,I've been looking at the documentation for a while and I can't figure out what I'm doing wrong. There doesn't seem to be an example to help guide a beginner in this process and the terms aren't exactly clear.I'm trying to draw a triangle with the coordinates (-1, -2), (0, -2), and (1, -2). The documentation for drawPolygon suggests it can take a list of coordinates or some type of array, but I can't find any examples or explanations for how the data should be entered and nothing I've tried has worked.drawPolygon(COORD) - what does it mean to 'pack' coords into a single array? How does one accomplish this?drawPolygon(PX, PY) - how do you specify the coordinates in different arrays? I tried passing in [-1 -2], [0 2], [1 -2] as well as [-1; -2], [0; 2], [1; -2] to no avail.drawPolygon(POLYS) - I looked up cell arrays, but none of the notation I've tried has worked here.My goal is to draw a triangle at the given coordinates and then draw it again on the same plot using a different color after applying a linear transformation to rotate it. Any help or guidance anyone can offer would be greatly appreciated.Thanks,Tony _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave  a= [ 1 1 ; 2 3; 4 2]drawPolygon(a)px=[-1 2 6 -1]py=[-3 4 -1 -3]drawPolygon(px',py')-- DAS _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave
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## Re: help drawing a polygon using drawPolygon

 Thanks for the help everyone. I was close it seems, but I didn't understand the syntax of any of the options, so none of them worked quite right. Now everything looks perfect.On Tue, Feb 21, 2017 at 8:06 AM, Doug Stewart wrote:On Tue, Feb 21, 2017 at 7:47 AM, Anthony Andriano wrote:Hello,I've been looking at the documentation for a while and I can't figure out what I'm doing wrong. There doesn't seem to be an example to help guide a beginner in this process and the terms aren't exactly clear.I'm trying to draw a triangle with the coordinates (-1, -2), (0, -2), and (1, -2). The documentation for drawPolygon suggests it can take a list of coordinates or some type of array, but I can't find any examples or explanations for how the data should be entered and nothing I've tried has worked.drawPolygon(COORD) - what does it mean to 'pack' coords into a single array? How does one accomplish this?drawPolygon(PX, PY) - how do you specify the coordinates in different arrays? I tried passing in [-1 -2], [0 2], [1 -2] as well as [-1; -2], [0; 2], [1; -2] to no avail.drawPolygon(POLYS) - I looked up cell arrays, but none of the notation I've tried has worked here.My goal is to draw a triangle at the given coordinates and then draw it again on the same plot using a different color after applying a linear transformation to rotate it. Any help or guidance anyone can offer would be greatly appreciated.Thanks,Tony _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave  a= [ 1 1 ; 2 3; 4 2]drawPolygon(a)px=[-1 2 6 -1]py=[-3 4 -1 -3]drawPolygon(px',py')-- DAS _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave
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## Re: help drawing a polygon using drawPolygon

 In reply to this post by James Sherman fyi i uploaded a patch added some clarifying text on input format to the function documentation https://savannah.gnu.org/bugs/index.php?50370On Tue, Feb 21, 2017 at 9:34 AM, James Sherman Jr. <[hidden email]> wrote: > On Tue, Feb 21, 2017 at 7:47 AM, Anthony Andriano > <[hidden email]> wrote: >> Hello, >> >> I've been looking at the documentation for a while and I can't figure out >> what I'm doing wrong. There doesn't seem to be an example to help guide a >> beginner in this process and the terms aren't exactly clear. >> >> I'm trying to draw a triangle with the coordinates (-1, -2), (0, -2), and >> (1, -2). The documentation for drawPolygon suggests it can take a list of >> coordinates or some type of array, but I can't find any examples or >> explanations for how the data should be entered and nothing I've tried has >> worked. >> >> drawPolygon(COORD) - what does it mean to 'pack' coords into a single array? >> How does one accomplish this? >> >> drawPolygon(PX, PY) - how do you specify the coordinates in different >> arrays? I tried passing in [-1 -2], [0 2], [1 -2] as well as [-1; -2], [0; >> 2], [1; -2] to no avail. >> >> drawPolygon(POLYS) - I looked up cell arrays, but none of the notation I've >> tried has worked here. >> >> My goal is to draw a triangle at the given coordinates and then draw it >> again on the same plot using a different color after applying a linear >> transformation to rotate it. Any help or guidance anyone can offer would be >> greatly appreciated. >> >> Thanks, >> Tony >> >> _______________________________________________ >> Help-octave mailing list >> [hidden email] >> https://lists.gnu.org/mailman/listinfo/help-octave>> > > Hi Anthony, > > I can't check right now, but my guess is, for the second way to call > drawPolygon, PX stands for the x coordinates of your polygon, and PY > stands for the y coordinates of the polygon, so, try something like: > PX = [-1 0 1]; > PY = [-2 2 -2]; > drawPolygon(PX, PY); > > Hope this helps. > > James Sherman > > _______________________________________________ > Help-octave mailing list > [hidden email] > https://lists.gnu.org/mailman/listinfo/help-octave_______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave