Hi again,
I'm writing a small package that builds on graphtool, but not on its graphics capabilities (also because I have to represent other things rather than the graph itself). Still I could use some of the functions "under the hood" for my purposes. I have a question about gt.draw.get_hierarchy_control_points(): the function returns the Bézier spline control points for edges in a given graph, but I'm having difficulties in understanding how this information is encoded. For a single edge in graph, I have dozens of values as control points (half dozens + 2), hence I suspect all splines going from node A to the root of a hierarchy and back to node B are encoded there, and control points should be taken 6 by 6 (3x2 by 3x2 coordinates?). How (x,y) for control points are encoded then: (x, x, x, y, y, y) or (x, y, x, y, x, y)? What are the 2 additiona values I have for each vector? Also, are values absolute or relative to one node in particular (A, B or root...)? Thanks d _______________________________________________ graphtool mailing list [hidden email] https://lists.skewed.de/mailman/listinfo/graphtool 
Hi,
I have the same question, except that in my case I do not have always the same number of points.... Did you find any information on that? A.  Sent from: https://nabble.skewed.de/ _______________________________________________ graphtool mailing list [hidden email] https://lists.skewed.de/mailman/listinfo/graphtool 
Administrator

In reply to this post by dawe
Am 25.11.20 um 18:38 schrieb AntoineR:
> Hi, > I would like to know also how the info are formatted... In my case the > length of the property is not the same across the edges... The documentation of graph_draw() for "edge_control_points" says: Control points of a Bézier spline used to draw the edge. Each spline segment requires 6 values corresponding to the (x,y) coordinates of the two intermediary control points and the final point. Bézier splines are defined as such: https://en.wikipedia.org/wiki/B%C3%A9zier_curve Best, Tiago  Tiago de Paula Peixoto <[hidden email]> _______________________________________________ graphtool mailing list [hidden email] https://lists.skewed.de/mailman/listinfo/graphtool OpenPGP_0x612DEFB798507F25.asc (40K) Download Attachment OpenPGP_signature (849 bytes) Download Attachment

Tiago de Paula Peixoto <tiago@skewed.de> 
Hi Tiago,
Sure the documentation states that there should be 6 points, but in my case the length of the map is variable, so I think that either the documentation is outdated, or the format of the map is not correct. Sometimes I have a length of 40 for the vector, sometimes 50 or so. Thanks, A.  Sent from: https://nabble.skewed.de/ _______________________________________________ graphtool mailing list [hidden email] https://lists.skewed.de/mailman/listinfo/graphtool 
Administrator

Am 30.11.20 um 18:38 schrieb AntoineR:
> Hi Tiago, > Sure the documentation states that there should be 6 points, but in my case > the length of the map is variable, so I think that either the documentation > is outdated, or the format of the map is not correct. Sometimes I have a > length of 40 for the vector, sometimes 50 or so. The documentation clearly states that it's 6 values *per spline segment*, of which there can be an arbitrary amount.  Tiago de Paula Peixoto <[hidden email]> _______________________________________________ graphtool mailing list [hidden email] https://lists.skewed.de/mailman/listinfo/graphtool OpenPGP_0x612DEFB798507F25.asc (40K) Download Attachment OpenPGP_signature (849 bytes) Download Attachment

Tiago de Paula Peixoto <tiago@skewed.de> 
Ok, that seems right, but still, there is something that I do not understand.
I followed the piece of code of the documentation of graph_tool.draw.get_hierarchy_control_points <https://graphtool.skewed.de/static/doc/draw.html?highlight=get_hierarchy_control_points#graph_tool.draw.get_hierarchy_control_points> , and when I print the length of the map /cts/ I get value that are not divisible by 6 (86,50,38,62...), so there is one more point coming out of the function /get_hierarchy_control_points/ and used in /graph_draw/. But thanks for the clarification of the several spline segments. I didn't get that. A  Sent from: https://nabble.skewed.de/ _______________________________________________ graphtool mailing list [hidden email] https://lists.skewed.de/mailman/listinfo/graphtool 
Administrator

Am 30.11.20 um 19:08 schrieb AntoineR:
> Ok, that seems right, but still, there is something that I do not understand. > I followed the piece of code of the documentation of > graph_tool.draw.get_hierarchy_control_points > <https://graphtool.skewed.de/static/doc/draw.html?highlight=get_hierarchy_control_points#graph_tool.draw.get_hierarchy_control_points> > , and when I print the length of the map /cts/ I get value that are not > divisible by 6 (86,50,38,62...), so there is one more point coming out of > the function /get_hierarchy_control_points/ and used in /graph_draw/. Yes, this is because of a boundary condition: The last point does not need to be specified, just as the first one. If it's given, it's ignored. The function get_hierarchy_control_points generates the final point because it's slightly easier in the code.  Tiago de Paula Peixoto <[hidden email]> _______________________________________________ graphtool mailing list [hidden email] https://lists.skewed.de/mailman/listinfo/graphtool OpenPGP_0x612DEFB798507F25.asc (40K) Download Attachment OpenPGP_signature (849 bytes) Download Attachment

Tiago de Paula Peixoto <tiago@skewed.de> 
Ok, but then I should be able to find the edge's target position in the
points generated by the the function get_hierarchy_control_points right? If it is not the last two components of the vector (boundary condition?) it should at the position [4:3]? If I understand correctly what you said, from the function get_hierarchy_control_points I should get n*(6 components) I got n*(6 components)+2. The last two are not used because there are boundary conditions (I do not get this but I need to read the paper you are citing, and I cannot access it right now because I cannot reach sci hub...). The 6 components are from the 3 points, 2 intermediates, 1 finale. The finale is the target right? So for get_hierarchy_control_points each [6n+4:6n+5] coordinates are coordinates of a target in the hierarchical graph. But the very last coordinates is the edge's target, isn't it?  Sent from: https://nabble.skewed.de/ _______________________________________________ graphtool mailing list [hidden email] https://lists.skewed.de/mailman/listinfo/graphtool 
Free forum by Nabble  Edit this page 