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Gerber plot solder mask margin: use new algo from master branch to avoid 

merging pad shapes when the min width mask is not 0.

Keeping pad shapes clearly identified in Gerber files is mandatory,
so the initial algo that merged shapes in some cases was not good
from this point of view.
This commit is contained in:
jean-pierre charras 2020-06-21 20:47:58 +02:00
parent 26035d23fe
commit a0ce1491d9
1 changed files with 121 additions and 17 deletions
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138
pcbnew/plot_board_layers.cpp
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@ -8,7 +8,7 @@
/*
* This program source code file is part of KiCad, a free EDA CAD application.
*
* Copyright (C) 1992-2017 KiCad Developers, see AUTHORS.txt for contributors.
* Copyright (C) 1992-2020 KiCad Developers, see AUTHORS.txt for contributors.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
@ -370,7 +370,11 @@ void PlotStandardLayer( BOARD *aBoard, PLOTTER* aPlotter,
wxSize extraSize = margin * 2;
extraSize.x += width_adj;
extraSize.y += width_adj;
// Store these parameters that can be modified to plot inflated/deflated pads shape
wxSize deltaSize = pad->GetDelta(); // has meaning only for trapezoidal pads
PAD_SHAPE_T padShape = pad->GetShape();
double padCornerRadius = pad->GetRoundRectCornerRadius();
if( pad->GetShape() == PAD_SHAPE_TRAPEZOID )
{ // The easy way is to use BuildPadPolygon to calculate
@ -437,8 +441,16 @@ void PlotStandardLayer( BOARD *aBoard, PLOTTER* aPlotter,
itemplotter.PlotPad( pad, color, plotMode );
break;
case PAD_SHAPE_TRAPEZOID:
case PAD_SHAPE_RECT:
if( margin.x > 0 )
{
pad->SetShape( PAD_SHAPE_ROUNDRECT );
pad->SetSize( padPlotsSize );
pad->SetRoundRectCornerRadius( margin.x );
}
// Fall through
case PAD_SHAPE_TRAPEZOID:
case PAD_SHAPE_ROUNDRECT:
pad->SetSize( padPlotsSize );
itemplotter.PlotPad( pad, color, plotMode );
@ -471,8 +483,11 @@ void PlotStandardLayer( BOARD *aBoard, PLOTTER* aPlotter,
break;
}
// Restore the pad parameters modified by the plot code
pad->SetSize( tmppadsize ); // Restore the pad size
pad->SetDelta( deltaSize );
pad->SetShape( padShape );
pad->SetRoundRectCornerRadius( padCornerRadius );
}
aPlotter->EndBlock( NULL );
@ -763,12 +778,25 @@ void PlotLayerOutlines( BOARD* aBoard, PLOTTER* aPlotter,
* mask clearance only (because deflate sometimes creates shape artifacts)
* 5 - draw result as polygons
*
* TODO:
* make this calculation only for shapes with clearance near than (min width solder mask)
* (using DRC algo)
* plot all other shapes by flashing the basing shape
* (shapes will be better, and calculations faster)
* We have 2 algos:
* the initial algo, that create polygons for every shape, inflate and deflate polygons
* with Min Thickness/2, and merges the result.
* Drawback: pads attributes are lost (annoying in Gerber)
* the new algo:
* create initial polygons for every shape (pad or polygon),
* inflate and deflate polygons
* with Min Thickness/2, and merges the result (like initial algo)
* remove all initial polygons.
* The remaining polygons are areas with thickness < min thickness
* plot all initial shapes by flashing (or using regions) for pad and polygons
* (shapes will be better) and remaining polygons to
* remove areas with thickness < min thickness from final mask
*
* TODO: remove old code after more testing.
*/
#define NEW_ALGO 1
extern void KeepPolyInside( bool aInside );
void PlotSolderMaskLayer( BOARD *aBoard, PLOTTER* aPlotter,
LSET aLayerMask, const PCB_PLOT_PARAMS& aPlotOpt,
int aMinThickness )
@ -784,8 +812,12 @@ void PlotSolderMaskLayer( BOARD *aBoard, PLOTTER* aPlotter,
itemplotter.SetLayerSet( aLayerMask );
// Plot edge layer and graphic items.
// They do not have a solder Mask margin, because they graphic items
// They do not have a solder Mask margin, because they graphic items
// on this layer (like logos), not actually areas around pads.
// Normal mode to generate polygons from shapes with arcs, if any:
DisableArcRadiusCorrection( false );
itemplotter.PlotBoardGraphicItems();
for( MODULE* module = aBoard->m_Modules; module; module = module->Next() )
@ -817,8 +849,19 @@ void PlotSolderMaskLayer( BOARD *aBoard, PLOTTER* aPlotter,
// This extra margin is used to merge too close shapes
// (distance < aMinThickness), and will be removed when creating
// the actual shapes
SHAPE_POLY_SET areas; // Contains shapes to plot
SHAPE_POLY_SET initialPolys; // Contains exact shapes to plot
// Will contain shapes inflated by inflate value that will be merged and deflated by
// inflate value to build final polygons
// After calculations the remaining polygons are polygons to plot
SHAPE_POLY_SET areas;
// Will contain exact shapes of all items on solder mask
SHAPE_POLY_SET initialPolys;
#if NEW_ALGO
// Generate polygons with arcs inside the shape or exact shape
// to minimize shape changes created by arc to segment size correction.
DisableArcRadiusCorrection( true );
#endif
/* calculates the coeff to compensate radius reduction of holes clearance
* due to the segment approx ( 1 /cos( PI/circleToSegmentsCount )
@ -829,10 +872,10 @@ void PlotSolderMaskLayer( BOARD *aBoard, PLOTTER* aPlotter,
// Plot pads
for( MODULE* module = aBoard->m_Modules; module; module = module->Next() )
{
// add shapes with exact size
// add shapes with their exact mask layer size in initialPolys
module->TransformPadsShapesWithClearanceToPolygon( layer,
initialPolys, 0, circleToSegmentsCount, correction );
// add shapes inflated by aMinThickness/2
// add shapes inflated by aMinThickness/2 in areas
module->TransformPadsShapesWithClearanceToPolygon( layer,
areas, inflate, circleToSegmentsCount, correction );
}
@ -865,12 +908,12 @@ void PlotSolderMaskLayer( BOARD *aBoard, PLOTTER* aPlotter,
if( !( via_set & aLayerMask ).any() )
continue;
via->TransformShapeWithClearanceToPolygon( areas, via_margin,
circleToSegmentsCount,
correction );
// add shapes with their exact mask layer size in initialPolys
via->TransformShapeWithClearanceToPolygon( initialPolys, via_clearance,
circleToSegmentsCount,
correction );
circleToSegmentsCount, correction );
// add shapes inflated by aMinThickness/2 in areas
via->TransformShapeWithClearanceToPolygon( areas, via_margin,
circleToSegmentsCount, correction );
}
}
@ -888,12 +931,24 @@ void PlotSolderMaskLayer( BOARD *aBoard, PLOTTER* aPlotter,
if( zone->GetLayer() != layer )
continue;
// add shapes inflated by aMinThickness/2 in areas
zone->TransformOutlinesShapeWithClearanceToPolygon( areas,
inflate+zone_margin, false );
// add shapes with their exact mask layer size in initialPolys
zone->TransformOutlinesShapeWithClearanceToPolygon( initialPolys,
zone_margin, false );
}
// Merge all polygons: After deflating, not merged (not overlapping) polygons
// will have the initial shape (with perhaps small changes due to deflating transform)
areas.Simplify( SHAPE_POLY_SET::PM_STRICTLY_SIMPLE );
areas.Inflate( -inflate, circleToSegmentsCount );
// Restore normal option to build polygons from item shapes:
DisableArcRadiusCorrection( false );
#if !NEW_ALGO
// To avoid a lot of code, use a ZONE_CONTAINER
// to handle and plot polygons, because our polygons look exactly like
// filled areas in zones
@ -916,6 +971,55 @@ void PlotSolderMaskLayer( BOARD *aBoard, PLOTTER* aPlotter,
zone.SetFilledPolysList( areas );
itemplotter.PlotFilledAreas( &zone );
#else
// Remove initial shapes: each shape will be added later, as flashed item or region
// with a suitable attribute.
// Do not merge pads is mandatory in Gerber files: They must be indentified as pads
// we deflate areas in polygons, to avoid after subtracting initial shapes
// having small artifacts due to approximations during polygon transforms
areas.BooleanSubtract( initialPolys, SHAPE_POLY_SET::PM_STRICTLY_SIMPLE );
// Slightly inflate polygons to avoid any gap between them and other shapes,
// These gaps are created by arc to segments approximations
areas.Inflate( Millimeter2iu( 0.002 ),6 );
// Now, only polygons with a too small thickness are stored in areas.
areas.Fracture( SHAPE_POLY_SET::PM_STRICTLY_SIMPLE );
// Plot each initial shape (pads and polygons on mask layer), with suitable attributes:
PlotStandardLayer( aBoard, aPlotter, aLayerMask, aPlotOpt );
// Add shapes corresponding to areas having too small thickness.
std::vector<wxPoint> cornerList;
for( int ii = 0; ii < areas.OutlineCount(); ii++ )
{
cornerList.clear();
const SHAPE_LINE_CHAIN& path = areas.COutline( ii );
// polygon area in mm^2 :
double curr_area = path.Area() / ( IU_PER_MM * IU_PER_MM );
// Skip very small polygons: they are certainly artifacts created by
// arc approximations and polygon transforms
// (inflate/deflate transforms)
constexpr double poly_min_area_mm2 = 0.01; // 0.01 mm^2 gives a good filtering
if( curr_area < poly_min_area_mm2 )
continue;
for( int jj = 0; jj < path.PointCount(); jj++ )
cornerList.emplace_back( (wxPoint) path.CPoint( jj ) );
// Ensure the polygon is closed
if( cornerList[0] != cornerList[cornerList.size() - 1] )
cornerList.push_back( cornerList[0] );
aPlotter->PlotPoly( cornerList, FILLED_SHAPE );
}
#endif
}