Fill a float distance array with the values 0 and INFINITY and then call:
df(squared_distances, nx, ny, closest_points);#define DF_IMPLEMENTATION
#include "df.h"
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <math.h>
int main(){
int i;
int nx = 1920;
int ny = 1080;
FILE *fp;
/* Pixels for image of distance field. */
uint8_t *pixels = (uint8_t*)calloc(nx*ny, 3);
/* Colors for voronoi diagram. */
uint8_t *colors = (uint8_t*)calloc(nx*ny, 3);
float *squared_distances = (float*)malloc(nx*ny*sizeof(*squared_distances));
df_point *closest_points = (df_point*)calloc(nx*ny, sizeof(*closest_points));
/* Initialize distances to infinity. */
for (i = 0; i < nx*ny; i++){
squared_distances[i] = DF_INFINITY;
}
/* Except some random points. */
for (i = 0; i < 100; i++){
int x = rand() % nx;
int y = rand() % ny;
int j = x + y*nx;
/* Other distance values than 0 and INFINITY work, too! */
squared_distances[j] = 0.0f;
colors[j*3 + 0] = rand();
colors[j*3 + 1] = rand();
colors[j*3 + 2] = rand();
}
/* Calculate squared distance field. */
/* Last parameter may be NULL if not needed. */
df(squared_distances, nx, ny, closest_points);
/* Draw voronoi diagram. */
for (i = 0; i < nx*ny; i++){
df_point p = closest_points[i];
int j = p.x + p.y*nx;
pixels[i*3 + 0] = colors[j*3 + 0];
pixels[i*3 + 1] = colors[j*3 + 1];
pixels[i*3 + 2] = colors[j*3 + 2];
}
/* Write ppm image file of voronoi diagram. */
fp = fopen("voronoi.ppm", "wb");
fprintf(fp, "P6\n%d %d\n255\n", nx, ny);
fwrite(pixels, 1, 3*nx*ny, fp);
fclose(fp);
/* Draw distance field. */
for (i = 0; i < nx*ny; i++){
float d = sqrt(squared_distances[i]);
pixels[i] = d > 255 ? 255 : d;
}
/* Write pgm image file of distance field. */
fp = fopen("df.pgm", "wb");
fprintf(fp, "P5\n%d %d\n255\n", nx, ny);
fwrite(pixels, 1, nx*ny, fp);
fclose(fp);
/* Cleanup. */
free(pixels);
free(squared_distances);
free(closest_points);
free(colors);
return 0;
}
