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src/vec_grid.cpp

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+/*
+ * This program source code file is part of KICAD, a free EDA CAD application.
+ *
+ * Copyright (C) 2021 Jan Sebastian Götte <kicad@jaseg.de>
+ * Copyright (C) 2021 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
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+#include "poisson_disk_sampling.h"
+
+#include "vec_grid.h"
+
+using namespace std;
+using namespace vectorizer;
+
+sampling_fun vectorizer::get_sampler(enum grid_type type) {
+    switch(type) {
+        case POISSON_DISC:
+            return sample_poisson_disc;
+        case HEXGRID:
+            return sample_hexgrid;
+        case SQUAREGRID:
+            return sample_squaregrid;
+        default:
+            return sample_poisson_disc;
+    }
+}
+
+vector<d2p> *vectorizer::sample_poisson_disc(double w, double h, double center_distance) {
+    d2p top_left {0, 0};
+    d2p bottom_right {w, h};
+    return new auto(thinks::PoissonDiskSampling(center_distance, top_left, bottom_right));
+}
+
+vector<d2p> *vectorizer::sample_hexgrid(double w, double h, double center_distance) {
+    double radius = center_distance / 2.0 / (sqrt(3) / 2.0); /* radius of hexagon */
+    double pitch_v = 1.5 * radius;
+    double pitch_h = center_distance;
+
+    /* offset of first hexagon to make sure the entire area is covered. We use slightly larger values here to avoid
+     * corner cases during clipping in the voronoi map generator.  The inaccuracies this causes at the edges are
+     * negligible. */
+    double off_x = 0.5001 * center_distance;
+    double off_y = 0.5001 * radius;
+
+    /* NOTE: The voronoi generator is not quite stable when points lie outside the bounds. Thus, floor(). */
+    long long int points_x = floor(w / pitch_h);
+    long long int points_y = floor(h / pitch_v);
+
+    vector<d2p> *out = new vector<d2p>();
+    out->reserve((points_x+1) * points_y);
+
+    /* This may generate up to one extra row of points. We don't care since these points will simply be clipped during
+     * voronoi map generation. */
+    for (long long int y_i=0; y_i<points_y; y_i+=2) {
+        for (long long int x_i=0; x_i<points_x; x_i++) { /* allow one extra point to compensate for row shift */
+            out->push_back(d2p{off_x + x_i * pitch_h, off_y + y_i * pitch_v});
+        }
+
+        for (long long int x_i=0; x_i<points_x+1; x_i++) { /* allow one extra point to compensate for row shift */
+            out->push_back(d2p{off_x + (x_i - 0.5) * pitch_h, off_y + (y_i + 1) * pitch_v});
+        }
+    }
+
+    return out;
+}
+
+vector<d2p> *vectorizer::sample_squaregrid(double w, double h, double center_distance) {
+    /* offset of first square to make sure the entire area is covered. We use slightly larger values here to avoid
+     * corner cases during clipping in the voronoi map generator.  The inaccuracies this causes at the edges are
+     * negligible. */
+    double off_x = 0.5 * center_distance;
+    double off_y = 0.5 * center_distance;
+
+    long long int points_x = ceil(w / center_distance);
+    long long int points_y = ceil(h / center_distance);
+
+    vector<d2p> *out = new vector<d2p>();
+    out->reserve(points_x * points_y);
+
+    for (long long int y_i=0; y_i<points_y; y_i++) {
+        for (long long int x_i=0; x_i<points_x; x_i++) {
+            out->push_back({off_x + x_i*center_distance, off_y + y_i*center_distance});
+        }
+    }
+
+    return out;
+}
+