The non-zero width edges might be creating even larger problems. If we have a round edge and we generate 32 segments for it, and those segments are non-zero width, then don’t we generate another 32 lines at the end of each segment to make it round? Or do we use some kind of shader there?
> On 10 May 2019, at 18:30, Mário Luzeiro <[email protected]> wrote: > > Hi Tomasz, > > This is an interesting challenge! > > Did you consider other approaches apart from the ones you listed? > > I have no full knowledge how GAL is rendering so maybe some of my suggestions > may not make sense. > > I believe GAL is already doing some cache of the layers using textures. > It may not be possible to get a full buffer resolution of the board ( eg > memory limitation? ) > but could be possible to implement some kind of techniques used on game > engines? > For instance: trying to render just the visible part of the board ( culling ) > or on the case on render the full board, implement some kind of "level of > detail" to render a less accurate version ? ( eg as you pointed the vias > could be a special case and simplified while on distance ) > > Out of curiosity, is 3D viewer able to render that board? :P > Would be possible to share that Victor-s project or where we can get it? > > Regards, > Mario Luzeiro > > ________________________________________ > From: Kicad-developers > <[email protected]> on behalf of > Tomasz Wlostowski <[email protected]> > Sent: 10 May 2019 17:33 > To: Kicad Developers > Subject: [Kicad-developers] Kicad's way of drawing filled zones > > Hi, > > I've been recently playing with Victor's huge 32-layer PCB design and > trying to improve the performance of pcbnew for larger designs. This > board causes even pretty decent PCs to crash/render glitches due to > pcbnew's enormous VBO (Vertex Buffer) memory consumption. > > It turns out it's caused by the way KiCad renders filled zones: > - the inside of a zone is drawn/plotted as a filled polygon with 0-width > boundary. This one not a problem - we already triangulate the polygons > and I recently developed a patch for the OpenGL GAL that allows reusing > vertices of triangulated polys in the VBO/Index buffer to further reduce > memory footprint. > - the thick outline is drawn with rounded segments with the width = > minimum width of the polygon. Since we don't have arcs in polygons, each > of round features (e.g. vias) surrounded by a zone gets a ton of tiny > segments in the polygon outline. Each rounded segment in OpenGL is > composed of 2 triangles, hence 6 vertices (that can't be reused...). For > Victor's board it means 1 GB (sic!) of the VBO goes for outlines of the > polygons alone. Disabling the outline drawing makes the renderer work > smooth again. > > I've been experimenting with some ways to fix this: > - generating the thick outline strokes using a Geometry Shader (which > means bumping up GL 3.0+), which means farewell to many Linux/older > integrated Graphics users. > - caching a triangulated polygon which is a boolean sum of the filled > inside and the thick stroked outline. This takes a lot of time (~2 > minutes for Victor's design) to load and still takes quite a bit of VBO > memory. Another downside is that the polygons are not fully WYSIWYG > (outline segments have true rounded corners, while the corners of the > displayed shape would be approximated with line segments). > - change the way KiCad handles filled zones to calculate the (stroke + > inside) boolean sum during zone filling process. It means changes to the > plotting/GAL/3D code, but no changes to the file format. We'll also be > forced to inform the users that they have to refill the zones if they > read a file generated by an older KiCad version. > > > Which solution would you prefer? > Cheers, > Tom > > _______________________________________________ > Mailing list: https://launchpad.net/~kicad-developers > Post to : [email protected] > Unsubscribe : https://launchpad.net/~kicad-developers > More help : https://help.launchpad.net/ListHelp > > _______________________________________________ > Mailing list: https://launchpad.net/~kicad-developers > Post to : [email protected] > Unsubscribe : https://launchpad.net/~kicad-developers > More help : https://help.launchpad.net/ListHelp _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
