1 /*
2 * This program source code file is part of KiCad, a free EDA CAD application.
3 *
4 * Copyright (C) 2018 Jean-Pierre Charras, jp.charras at wanadoo.fr
5 * Copyright (C) 1992-2021 KiCad Developers, see AUTHORS.txt for contributors.
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 2
10 * of the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, you may find one here:
19 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
20 * or you may search the http://www.gnu.org website for the version 2 license,
21 * or you may write to the Free Software Foundation, Inc.,
22 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
23 */
24
25 /**
26 * @file geometry_utils.h
27 * @brief a few functions useful in geometry calculations.
28 */
29
30 #ifndef GEOMETRY_UTILS_H
31 #define GEOMETRY_UTILS_H
32
33 #include <math.h> // for copysign
34 #include <stdlib.h> // for abs
35
36 #include <math/vector2d.h>
37
38 class EDA_RECT;
39
40 /**
41 * When approximating an arc or circle, should the error be placed on the outside
42 * or inside of the curve? (Generally speaking filled shape errors go on the inside
43 * and knockout errors go on the outside. This preserves minimum clearances.)
44 */
45 enum ERROR_LOC { ERROR_OUTSIDE, ERROR_INSIDE };
46
47 /**
48 * @return the number of segments to approximate a arc by segments
49 * with a given max error (this number is >= 1)
50 * @param aRadius is the radius od the circle or arc
51 * @param aErrorMax is the max error
52 * This is the max distance between the middle of a segment and the circle.
53 * @param aArcAngleDegree is the arc angle in degrees
54 */
55 int GetArcToSegmentCount( int aRadius, int aErrorMax, double aArcAngleDegree );
56
57 /**
58 * @return the radius diffence of the circle defined by segments inside the circle
59 * and the radius of the circle tangent to the middle of segments (defined by
60 * segments outside this circle)
61 * @param aInnerCircleRadius is the radius of the circle tangent to the middle
62 * of segments
63 * @param aSegCount is the seg count to approximate the circle
64 */
65 int CircleToEndSegmentDeltaRadius( int aInnerCircleRadius, int aSegCount );
66
67 /**
68 * When creating polygons to create a clearance polygonal area, the polygon must
69 * be same or bigger than the original shape.
70 * Polygons are bigger if the original shape has arcs (round rectangles, ovals,
71 * circles...). However, when building the solder mask layer modifying the shapes
72 * when converting them to polygons is not acceptable (the modification can break
73 * calculations).
74 * So one can disable the shape expansion within a particular scope by allocating
75 * a DISABLE_ARC_CORRECTION.
76 */
77 class DISABLE_ARC_RADIUS_CORRECTION
78 {
79 public:
80 DISABLE_ARC_RADIUS_CORRECTION();
81 ~DISABLE_ARC_RADIUS_CORRECTION();
82 };
83
84 /**
85 * @return the radius correction to approximate a circle.
86 * @param aMaxError is the same error value used to calculate the number of segments.
87 *
88 * When creating a polygon from a circle, the polygon is inside the circle.
89 * Only corners are on the circle.
90 * This is incorrect when building clearance areas of circles, that need to build
91 * the equivalent polygon outside the circle.
92 */
93 int GetCircleToPolyCorrection( int aMaxError );
94
95 /**
96 * Snap a vector onto the nearest 0, 45 or 90 degree line.
97 *
98 * The magnitude of the vector is NOT kept, instead the coordinates are
99 * set equal (and/or opposite) or to zero as needed. The effect of this is
100 * that if the starting vector is on a square grid, the resulting snapped
101 * vector will still be on the same grid.
102
103 * @param a vector to be snapped
104 * @return the snapped vector
105 */
106 template<typename T>
107 VECTOR2<T> GetVectorSnapped45( const VECTOR2<T>& aVec, bool only45 = false )
108 {
109 auto newVec = aVec;
110 const VECTOR2<T> absVec { std::abs( aVec.x ), std::abs( aVec.y ) };
111
112 if ( !only45 && absVec.x > absVec.y * 2 )
113 {
114 // snap along x-axis
115 newVec.y = 0;
116 }
117 else if ( !only45 && absVec.y > absVec.x * 2 )
118 {
119 // snap onto y-axis
120 newVec.x = 0;
121 }
122 else if ( absVec.x > absVec.y )
123 {
124 // snap away from x-axis towards 45
125 newVec.y = std::copysign( aVec.x, aVec.y );
126 } else
127 {
128 // snap away from y-axis towards 45
129 newVec.x = std::copysign( aVec.y, aVec.x );
130 }
131
132 return newVec;
133 }
134
135
136 /**
137 * Test if any part of a line falls within the bounds of a rectangle.
138 *
139 * Please note that this is only accurate for lines that are one pixel wide.
140 *
141 * @param aClipBox - The rectangle to test.
142 * @param x1 - X coordinate of one end of a line.
143 * @param y1 - Y coordinate of one end of a line.
144 * @param x2 - X coordinate of the other end of a line.
145 * @param y2 - Y coordinate of the other end of a line.
146 *
147 * @return - False if any part of the line lies within the rectangle.
148 */
149 bool ClipLine( const EDA_RECT *aClipBox, int &x1, int &y1, int &x2, int &y2 );
150
151
152 /**
153 * Dashed and dotted line patterns.
154 */
155
dot_mark_len(double aLineWidth)156 constexpr double dot_mark_len( double aLineWidth )
157 {
158 return std::max( 1.0, aLineWidth );
159 }
160
dash_gap_len(double aLineWidth)161 constexpr double dash_gap_len( double aLineWidth )
162 {
163 return 3.0 * dot_mark_len( aLineWidth ) + ( 2.0 * aLineWidth );
164 }
165
dash_mark_len(double aLineWidth)166 constexpr double dash_mark_len( double aLineWidth )
167 {
168 return std::max( dash_gap_len( aLineWidth ), 5.0 * dot_mark_len( aLineWidth ) );
169 }
170
171 #endif // #ifndef GEOMETRY_UTILS_H
172
173