On Wed, 2008-05-21 at 09:06 +0100, Robert Fitzsimons wrote:
> The clearance polygon created around an angled square pad doesn't
> correctly follow the angle of pad, instead a non-angled round-corner
> rectangle is produced based on the extents of the square pad. The
> following patch will produce a suitably angled rounded-corner rectangle
> around the square pad.
>
> Robert
I remember debating this one before, it is intentional I think. The
clearance gap between the pad and the mask should be the same distance
all the way around.
I was unsure, but DJ convinced me.. this is right if the process
registration tolerance is just some normally distributed offset in both
the X and Y directions (independently).
I do agree that a square mask cutout would allow slightly more
registration error, e.g. maximum offset in X _and_ Y directions
simultaneously, for little loss otherwise.
Another consideration though, square mask cutouts are what other tools
seem to use. (This said, some use octagonal cutouts around round holes).
> Index: src/polygon.c
> ===================================================================
> RCS file: /cvsroot/pcb/pcb/src/polygon.c,v
> retrieving revision 1.59
> diff -u -r1.59 polygon.c
> --- src/polygon.c 2 Dec 2007 09:35:40 -0000 1.59
> +++ src/polygon.c 21 May 2008 07:43:17 -0000
> @@ -451,6 +451,77 @@
> return np;
> }
>
> +/* make a rounded-corner rectangle */
> +POLYAREA *
> +SquarePadPoly (PadType * pad)
> +{
> + PLINE *contour = NULL;
> + POLYAREA *np = NULL;
> + Vector v;
> + double d;
> + double tx, ty;
> + double cx, cy;
> + PadType _t=*pad,*t=&_t;
> + PadType _c=*pad,*c=&_c;
> + int halfthick = (pad->Thickness + 1) / 2;
> + int halfclear = (pad->Thickness + pad->Clearance + 1) / 2;
> +
> + d =
> + sqrt (SQUARE (pad->Point1.X - pad->Point2.X) +
> + SQUARE (pad->Point1.Y - pad->Point2.Y));
> + if (d != 0)
> + {
> + double a = halfthick / d;
> + tx = (t->Point1.Y - t->Point2.Y) * a;
> + ty = (t->Point2.X - t->Point1.X) * a;
> + a = halfclear / d;
> + cx = (c->Point1.Y - c->Point2.Y) * a;
> + cy = (c->Point2.X - c->Point1.X) * a;
> + }
> + else
> + {
> + tx = halfthick / 2;
> + ty = 0;
> + cx = halfclear / 2;
> + cy = 0;
> + }
> +
> + t->Point1.X -= ty;
> + t->Point1.Y += tx;
> + t->Point2.X += ty;
> + t->Point2.Y -= tx;
> + c->Point1.X -= cy;
> + c->Point1.Y += cx;
> + c->Point2.X += cy;
> + c->Point2.Y -= cx;
> +
> + v[0] = c->Point1.X - tx;
> + v[1] = c->Point1.Y - ty;
> + if ((contour = poly_NewContour (v)) == NULL)
> + return 0;
> + frac_circle (contour, (t->Point1.X - tx), (t->Point1.Y - ty), v, 4);
> +
> + v[0] = t->Point2.X - cx;
> + v[1] = t->Point2.Y - cy;
> + poly_InclVertex (contour->head.prev, poly_CreateNode (v));
> + frac_circle (contour, (t->Point2.X - tx), (t->Point2.Y - ty), v, 4);
> +
> + v[0] = c->Point2.X + tx;
> + v[1] = c->Point2.Y + ty;
> + poly_InclVertex (contour->head.prev, poly_CreateNode (v));
> + frac_circle (contour, (t->Point2.X + tx), (t->Point2.Y + ty), v, 4);
> +
> + v[0] = t->Point1.X + cx;
> + v[1] = t->Point1.Y + cy;
> + poly_InclVertex (contour->head.prev, poly_CreateNode (v));
> + frac_circle (contour, (t->Point1.X + tx), (t->Point1.Y + ty), v, 4);
> +
> + /* now we have the line contour */
> + if (!(np = ContourToPoly (contour)))
> + return NULL;
> + return np;
> +}
> +
> /* clear np1 from the polygon */
> static int
> Subtract (POLYAREA * np1, PolygonType * p, Boolean fnp)
> @@ -583,13 +654,8 @@
>
> if (TEST_FLAG (SQUAREFLAG, pad))
> {
> - BDimension t = pad->Thickness / 2;
> - LocationType x1, x2, y1, y2;
> - x1 = MIN (pad->Point1.X, pad->Point2.X) - t;
> - x2 = MAX (pad->Point1.X, pad->Point2.X) + t;
> - y1 = MIN (pad->Point1.Y, pad->Point2.Y) - t;
> - y2 = MAX (pad->Point1.Y, pad->Point2.Y) + t;
> - if (!(np = RoundRect (x1, x2, y1, y2, pad->Clearance / 2)))
> + if (!
> + (np = SquarePadPoly (pad)))
> return -1;
> }
> else
>
>
>
>
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--
Peter Clifton
Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA
Tel: +44 (0)7729 980173 - (No signal in the lab!)
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