#include <stdio.h>
#include <gd.h>
#include <math.h>
void draw_star(gdImagePtr img, int x, int y, int size, int color, int rotation);
void draw_proc_flag(gdImagePtr img);
int main() {
int width = 1200;
int height = (int)(width * 2.0 / 3.0);
gdImagePtr img = gdImageCreateTrueColor(width, height);
gdImageAlphaBlending(img, 0);
draw_proc_flag(img);
FILE *outputFile = fopen("Y:/tmp/c_ex/proc01.png", "wb");
if (outputFile == NULL) {
fprintf(stderr, "Error opening the output file.\n");
return 1;
}
gdImagePngEx(img, outputFile, 9);
fclose(outputFile);
gdImageDestroy(img);
return 0;
}
void draw_star(gdImagePtr img, int x, int y, int size, int color, int rotation) {
double deg = M_PI / 180.0;
gdPoint points[10];
int num_points = 10;
for (int i = 0; i < num_points; i++) {
double angle = M_PI / 2 + i * 2 * M_PI / 10 + rotation * deg;
int radius = (i % 2 == 0) ? size : size * sin(18 * deg) / cos(36 * deg);
points[i].x = x + radius * cos(angle);
points[i].y = y - radius * sin(angle);
}
gdImageFilledPolygon(img, points, num_points, color);
}
void draw_proc_flag(gdImagePtr img) {
double deg = M_PI / 180.0;
int width = gdImageSX(img);
int height = gdImageSY(img);
int red, yellow;
double angle;
int center_x = (int)(width / 6);
int center_y = (int)(height / 4);
int big_star_radius = (int)(width / 10);
int small_star_radius = (int)(width / 30);
red = gdImageColorAllocate(img, 238, 28, 37);
yellow = gdImageColorAllocate(img, 255, 255, 0);
gdImageFilledRectangle(img, 0, 0, width, height, red);
draw_star(img, center_x, center_y, big_star_radius, yellow, 0);
center_x = (int) width/3;
center_y = (int) width/15;
angle = 180 - atan(5/3)/deg;
draw_star(img, center_x, center_y, small_star_radius, yellow, angle);
center_x = (int) 2*width/5;
center_y = (int) 2*width/15;
angle = 180 - atan(7/1)/deg;
draw_star(img, center_x, center_y, small_star_radius, yellow, angle);
center_x = (int) 2*width/5;
center_y = (int) 7*width/30;
angle = atan(7/2)/deg;
draw_star(img, center_x, center_y, small_star_radius, yellow, angle);
center_x = (int) width/3;
center_y = (int) 3*width/10;
angle = atan(5/4)/deg;
draw_star(img, center_x, center_y, small_star_radius, yellow, angle);
}