> I'm trying to compile your examples, but it seems perhaps you forget to include a file
Sorry, you can find pixel_formats.h in the examples directory. I have a mirror of agg here: https://github.com/pelson/antigrain/tree/master/agg-2.4/examples My compile steps are: export AGG_DIR=<path to antigrain checkout> g++ -c -O3 -I${AGG_DIR}/include -I${AGG_DIR}/examples -L${AGG_DIR}/src basic_path.cpp -o basic_path.o g++ -O3 -I${AGG_DIR}/include -L${AGG_DIR}/src basic_path.o -o basic_path -lagg > I had played with the "compound renderer" example in Agg some years ago, but couldn't really understand how it worked Agreed. It took the best part of a day to figure out how to do it, given no prior knowledge of Agg. I intend to submit a couple of simpler (GUI-less) examples to be included with the agg repo - and perhaps even write some documentation for this stuff! > Does it work with alpha < 1? Yes. I've attached the two images (converted from ppm to png using gimp + default settings) so that you can see the results. Each shape has an alpha value of 200. [image: Inline images 1][image: Inline images 2] HTH On 6 March 2013 20:27, Michael Droettboom <md...@stsci.edu> wrote: > I'm trying to compile your examples, but it seems perhaps you forget to > include a file -- pixel_formats.hpp? It's not in the agg24 source tree. > > Mike > > > On 03/06/2013 12:06 PM, Phil Elson wrote: > > Smart rendering of adjacent, anti-aliased patches is a question which > has come up a couple of times in various guises in the past. > It is my understanding that the lack of this functionality led us to > disable anti-aliasing for contouring and is the reason the following image > has a white stripe around the circle where there should be just a nice > blend of the two colors: > > > import matplotlib.pyplot as plt > import numpy as np > import matplotlib.patches as mpatches > import matplotlib.path as mpath > import matplotlib.collections as mcol > > > # create two paths. One a circle, the other > # a square with the same circle cut out. > x = np.linspace(0, np.pi * 2, 1000) > > circle_coords = np.array(zip(*[np.sin(x) * 0.8, np.cos(x) * 0.8])) > pth_circle = mpath.Path(circle_coords) > > sqr_codes = np.repeat(mpath.Path.MOVETO, len(circle_coords) + 5) > sqr_codes[1:5] = mpath.Path.LINETO > sqr_codes[6:] = mpath.Path.LINETO > sqr_coords = np.concatenate([[[-1, -1], [-1, 1], [1, 1], [1, -1], [-1, > -1]], > circle_coords[::-1]], axis=0) > sqr_path = mpath.Path(sqr_coords, sqr_codes) > > > ax = plt.axes() > patches = [mpatches.PathPatch(pth_circle), mpatches.PathPatch(sqr_path)] > col = mcol.PatchCollection(patches, > antialiaseds=True, > edgecolors='none', > facecolors=[(0, 0.0, 0.0, 0.9), (0.1, 0.1, > 0.02, 0.9)]) > ax.add_collection(col) > ax.set_xlim([-1, 1]) > ax.set_ylim([-1, 1]) > plt.show() > > > > I know of lots of the workarounds for this (turn off AA, turn on lines, > extend the path slightly, set a dark background color) all of which have > down-sides, so I'm keen to find a final solution to the problem. > > When the two patches marry up perfectly with full anti-aliasing, the > antigrain (AGG) community call this "flash" or compound rendering, and this > capability was added to Agg 2.4 (which we already ship with mpl). > > In order to make full use of the compound rendering technique I believe > the drawing pipeline in "_backend_agg.cpp" would need to change, which > could be problematic. A less wide-impacting alternative would be to draw > all "patches" of a single Collection in the same rasterization step (i.e. > just change _draw_path_collection_generic), though this does mean that, as > it stands, the result of plt.contourf would not be able to make use of this > new functionality - a MEP which changes the return type of plt.contourf to > a single Collection might be able to fix that. > > I've put together a simple example similar to this in C++ using agg (no > mpl changes yet), showing the differences in the code needed between the > old technique vs the "new" compound renderer (attached). > > > Ok, so the question to those that have knowledge of the _backend_agg.cpp > code (Mike, Eric, JJ + others?): > > > - Have you already looked at doing this and determined that this is a > non-starter? > - Do you support adding the ability for the agg backend to draw > compound artists (i.e. Collections) in this way rather than treating them > as individual primitives in the canvas? > - Since many of the other backends can't do flash rendering, would we > even want to make this change? > - SVG in Firefox 10.0.2 has the same problem, it is discussed > slightly more in > http://www.svgopen.org/2002/papers/sorotokin__svg_secrets/ > - Acroread has the same problem with PDFs, only to a much lesser > extent than in the PNG attached > > > Thoughts? > > > > > > > > > > > > > ------------------------------------------------------------------------------ > Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester > Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the > endpoint security space. For insight on selecting the right partner to > tackle endpoint security challenges, access the full report. > http://p.sf.net/sfu/symantec-dev2dev > > > > _______________________________________________ > Matplotlib-devel mailing > listMatplotlib-devel@lists.sourceforge.nethttps://lists.sourceforge.net/lists/listinfo/matplotlib-devel > > > > > ------------------------------------------------------------------------------ > Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester > Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the > endpoint security space. For insight on selecting the right partner to > tackle endpoint security challenges, access the full report. > http://p.sf.net/sfu/symantec-dev2dev > _______________________________________________ > Matplotlib-devel mailing list > Matplotlib-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-devel > >
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------------------------------------------------------------------------------ Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the endpoint security space. For insight on selecting the right partner to tackle endpoint security challenges, access the full report. http://p.sf.net/sfu/symantec-dev2dev
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