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/*
* This file is part of gerbolyze, a vector image preprocessing toolchain
* Copyright (C) 2021 Jan Sebastian Götte <gerbolyze@jaseg.de>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "poisson_disk_sampling.h"
#include "vec_grid.h"
using namespace std;
using namespace gerbolyze;
sampling_fun gerbolyze::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> *gerbolyze::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/2.5, top_left, bottom_right));
}
vector<d2p> *gerbolyze::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> *gerbolyze::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;
}
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