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From: Francois M. <ma...@lp...> - 2015-04-07 13:13:42
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Dear Gnuploters, I use the splot command with some data file for 3D rendering with "wire" mode (no surfaces, facets ad the like). My datafiles provides collections of vertexes (polylines) representing the edges of 3D solid shapes managed by some external library. This is particularly useful to check/visualize if some virtual geometry setup is correct, helping to detect solid overlap... Unfortunately, the splot driver regularly and automatically switches to 'grid data' mode, adding annoying segments to connect some vertexes where I do not want to use this "isolines" features. Reading the doc explains why it works lie, this: <cite from="Gnuplot documentation"> If all datablocks contain the same number of points, gnuplot will draw cross-isolines between datablocks, connecting corresponding points. </cite> Example: here I want to draw 2 parallel vertical segments AB and CD: <pre> gnuplot> splot '-' with line 0 0 0 # vertex A 0 0 1 # vertex B 1 0 0 # vertex C 1 0 1 # vertex D e </pre> As both datablocks have 2 lines, the 'grid data' is activated and it plots a vertical square ABDC in place of my only 2 segments! For now I was not able to find a way (through a special option or command) that would inhibit this feature and I am forced to add arbitrary vertexes to break the 'grid data' feature: <pre> gnuplot> splot '-' with line 0 0 0 # vertex A 0 0 0.5 # trick: vertex 0.5*(A+B) is an additional mid-point for the first segment 0 0 1 # vertex B 1 0 0 # vertex C 1 0 1 # vertex D e </pre> this restores my "2 segments" plot because datablocks don't have the same number of vertexes. I'd like to know if there is some kind of "unset grid data" command or "splot 'a.data' index 0 nogriddata with lines" option ti inhibit this feature. If not it would be very useful to have it in gnuplot. I just want to plot a collection of simple polylines with arbitrary number of vertexes, no emulated grid-ed surfaces. Many thanks for any help or hint. fm -- François Mauger |