Voronoi图广泛应用在几何学、地理学、晶体学、信息系统等学科之中。Voronoi图是由图中各个相邻点连线的中垂线组成的连续多边形组成。图中的各个点归属于该点最邻近的多边形，如下图所示：

Voronoi图相应的C语言实现代码如下：

#include

#include

#include

#define N_SITES 150

double site[N_SITES][2];

unsigned char rgb[N_SITES][3];

int size_x = 640, size_y = 480;

inline double sq2(double x, double y)//square function

{

return x * x + y * y;

}

#define for_k for (k = 0; k < N_SITES; k++)//define for_k

int nearest_site(double x, double y) //get the nearest site id

{

int k, ret = 0;

double d, dist = 0;

for_k {

d = sq2(x - site[k][0], y - site[k][1]);

if (!k || d < dist) { //get the nearest distance

dist = d, ret = k;

}

}

return ret;

}

/* see if a pixel is different from any neighboring ones */

int at_edge(int *color, int y, int x)

{

int i, j, c = color[y * size_x + x];

for (i = y - 1; i <= y + 1; i++) {

if (i < 0 || i >= size_y) continue;

for (j = x - 1; j <= x + 1; j++) {

if (j < 0 || j >= size_x) continue;

if (color[i * size_x + j] != c) return 1;

}

}

return 0;

}

#define AA_RES 4 /* average over 4x4 supersampling grid */

void aa_color(unsigned char *pix, int y, int x) //get color for pix(x, y)

{

int i, j, n;

double r = 0, g = 0, b = 0, xx, yy;

for (i = 0; i < AA_RES; i++) {

yy = y + 1. / AA_RES * i + .5;

for (j = 0; j < AA_RES; j++) {

xx = x + 1. / AA_RES * j + .5;

n = nearest_site(xx, yy);

r += rgb[n][0];

g += rgb[n][1];

b += rgb[n][2];

}

}

pix[0] = r / (AA_RES * AA_RES);

pix[1] = g / (AA_RES * AA_RES);

pix[2] = b / (AA_RES * AA_RES);

}

#define for_i for (i = 0; i < size_y; i++)

#define for_j for (j = 0; j < size_x; j++)

void gen_map()

{

int i, j, k;

int *nearest = malloc(sizeof(int) * size_y * size_x);

unsigned char *ptr, *buf, color;

ptr = buf = malloc(3 * size_x * size_y);

for_i for_j nearest[i * size_x + j] = nearest_site(j, i);

for_i for_j {

if (!at_edge(nearest, i, j))

memcpy(ptr, rgb[nearest[i * size_x + j]], 3);

else/* at edge, do anti-alias rastering */

aa_color(ptr, i, j);

ptr += 3;

}

/* draw sites */

for (k = 0; k < N_SITES; k++) {

color = (rgb[k][0]*.25 + rgb[k][1]*.6 + rgb[k][2]*.15 > 80) ? 0 : 255;

for (i = site[k][1] - 1; i <= site[k][1] + 1; i++) {

if (i < 0 || i >= size_y) continue;

for (j = site[k][0] - 1; j <= site[k][0] + 1; j++) {

if (j < 0 || j >= size_x) continue;

ptr = buf + 3 * (i * size_x + j);

ptr[0] = ptr[1] = ptr[2] = color;

}

}

}

printf("P6\n%d %d\n255\n", size_x, size_y);

fflush(stdout);

fwrite(buf, size_y * size_x * 3, 1, stdout);

}

#define frand(x) (rand() / (1. + RAND_MAX) * x)

int main()

{

int k;

for_k {

site[k][0] = frand(size_x);

site[k][1] = frand(size_y);

rgb [k][0] = frand(256);

rgb [k][1] = frand(256);

rgb [k][2] = frand(256);

}

gen_map();

return 0;

}