Plot file (HPGL PLT file) conversion to image

[cassaniti]

Yes I got that! I understood that everything that comes after SP are plot coordinates and in my case i have five SP matches so I am creating a parser for the strings between SP. Once again, my issue is how to convert from plot position to "pixels" for my image.. I am using the parser here as inspiration, but once i have the array with the plot positions i don't know what to do.... thanks again for your help!

[GerdW]

Hi cassaniti,

read your own Wikipedia link and the descriptions of those HPGL commands.

One command of interest could be "SC" - it's one of the first commands in your PLT file…

The other interesting command is "IP"…

[cassaniti]

Thanks, i got that.. as i wrote i parsed 5 strings separated by SP where i have the points where plotter is supposed to draw. For example

SP2;;PU;PA0,0;PA244 ,136 ;PD;PA244 ,136 ;PA244 ,136 ;PA260 ,136 ;PA276 ,136 ;PA292 ,206 ;PA308 ,264 ;PA324 ,318 ;PA340 ,242 ;PA356 ,136 ;PA372 ,254

PA(Plot Absolute)
 Pen is moved to position of absolute coordinate (x, y).
   PA x,y(,x,y...);

what i don't get is how to convert those "coordinates" to pixels....

[GerdW]

what i don't get is how to convert those "coordinates" to pixels....

That's why you need commands IP and SC.

With those commands you can scale to any sheet of paper you like to!

It's similar to PDF format: you scale to an arbitrary position. This position is then converted to real pixels depending on your desired output format. (A greater sheet of paper might use more pixels than a smaller sheet!)

[cassaniti]

now I'm starting to feel ignorant or stupid 😄

IP250,279,10250,7479;

SC0 ,4388 ,0 ,4212

that's what I parsed.. then I have the array of coordinates.. which VI should I use to convert this to pixels? do you know something that i can use as an example to do this?!

[GerdW]

Hi cassaniti,

you make your own "sheet of paper" using your own coordinates.

For this you scale the coordinates of your HPGL file to your pixel coordinations.

When you define your image as 1000×1000 pixels you need to scale the range [250, 279, 10250, 7479] (given by IP command) to your pixels [0, 0, 999, 999]…

[cassaniti]

should i use this function http://zone.ni.com/reference/en-XX/help/371361H-01/lvpict/draw_point/ in a shift register with my x-y scaled coordinates? Or is it a stupid idea?!

[GerdW]

Hi cassaniti,

this is one of the picture drawing function which I suggested to use…

You can draw single points, you can draw lines, arcs, rectangles - just like HPGL commands…

[cassaniti]

interesting i'm starting to understand 😉 i will post my results (and hopefully a VI that the other people can eventually "recycle" )

[cassaniti]

as you can see from the attached screenshot, i've made some steps forward, but i'm having a weird issue: the origin of the labview image is on the top-left, while the coordinates i get are originated on the bottom left.. is there a way to change the origin of the image coordinates on labview? thanks