kicad-developers team mailing list archive

[jp charras <jp.charras@xxxxxxxxxx>]

Le 02/09/2018 à 12:39, Martin Laabs a écrit :
> Hi Jeff,
> 
> On 01.09.2018 12:40, Jeff Young wrote:
> 
>> What’s still missing is the Connection Algorithm (because they’re arcs
>> and not tracks).  That also means the DRC clearance calculations are
>> one-sided as they only take into account the clearance of the colliding
>> track or the zone (as the arcs are assumed to have a 0 clearance).
> 
> Is there is a document describing the DRC/Connectivity approach from
> KiCAD? I know at least one Layout-Tool which has a full connectivity
> check for any shape - independent from the actual shape.
> This is very cool since it handles even connections made by arbitrary
> imported shapes or connections made through pads touching each other.
> 
> With such an algorithm you don't have to care about the type or shape of
> an object which is great in terms of future-proofnes.


Hi Martin,

Have you more info about "DRC check for any shape independent from the
actual shape"

For the DRC tests with pads, Pcbnew uses 2 algorithms:
If the pad shape is a basic shape (circle, rect, oval) or can be reduced
to a few basic shapes (round rect pads) a fast test is made, with the
exact shape (with only rounding approximations in trigonometric
calculations)

When a pad has a complex shape (trapezoid, custom and future chamfered
pads) a polygonal shape is used.
Using a polygonal shape works for any shape, but has 2 issues:
- the shape is an approximation for every arc.
- I am guessing the calculation time is larger than for a basic shape
(especially if the polygon has a lot of vertices).

> 
> Best regards,
>  Martin

-- 
Jean-Pierre CHARRAS