kicad-developers team mailing list archive

[Mário Luzeiro <mrluzeiro@xxxxx>]

>> - I have in mind to try to make it as fast / interactive as possible, so it will need some specific implementation.. some hacks .. that will target this specific propose.

> I understand. Speed is definitely an issue with big boards. But I am
> no export in ray tracing characteristics, but what is the scalability
> of your implementation in reagard to board complexity (lots of holes
> and lots of other objects) and seperately about the screensize?

Actually, as I experienced, the size of the boards will not make a big impact in the loading/rendering. From the 'size' it means 'how much items/objects it will load/render'.
( Btw, anyone have a real real big board project for kicad? something like the complexity of a PC motherboard? )

Regarding the scalability, raytracing algos are very good to handle scalability. The limit of objects, are the u32 size and your RAM.
I am using some 'state-of-art' algos for ray traversal  (frustum packets over a bounding volume hierarchy). (BVH is based on the PBRT 3 book [1], and traversal is based on [2])
I means that it can adapt very well to any number of objects or configurations without suffering much penalty.

Loading the board is also very fast, creating the BVH will take some 200ms on complex boards.
The thing that will take more time is still some tessellation need for the polygon filled planes, but I have in mind some optimizations.
It means at the moment that loading a board like 'video' (from kicad's demo boards) or 'hackRF' takes about 3 seconds + render.
I plan to try to cache somehow the tesselation, so this time can be much more reduced.

Resolution is at moment set to the windows size, but for export rendering to image file, we can add a dialog to choose different  resolutions.
Of-course, more resolution means it will be more slow.

At this moment on my machine, rendering for quality takes about 1..2.3seconds (depend of the view) with all eye-candy features set. If some of that features are not used (eg: post shaders effects, refractions or shadows), the render can take less than 1s

Cheers,
Mario


[1] https://github.com/mmp/pbrt-v3/

[2] Wald, S. Boulos, and P. Shirley. Ray Tracing Deformable Scenes using Dynamic Bounding Volume Hierarchies. ACM TOG , 26(1), 2007
http://www.cs.cmu.edu/afs/cs/academic/class/15869-f11/www/readings/wald07_packetbvh.pdf
implementation of the algo based in the description from:
https://cseweb.ucsd.edu/~ravir/whitted.pdf