chaos_game_hexagon.c

// Pipe in random bytes, and it outputs alternting x and y ints of where to draw a low opacity point.
// Call from command line with an integer specifiying the output scale
#include "stdio.h"
#include <stdlib.h>
#include <stdint.h>

typedef struct {
    float x;
    float y;
} pair_t;

int frown(float x) {
    int x_int = (int) x;
    if (x - x_int >= 0.5)
        return x_int + 1;
    return x_int;
}

void draw(int x, int y) {
    fwrite((void*)&x, 1, sizeof(int), stdout);
    fwrite((void*)&y, 1, sizeof(int), stdout);
}

void drawf(float x, float y) {
    draw(frown(x), frown(y));
}

float better_random() {
    uint32_t x;
    fgets((void*) &x, sizeof(uint32_t), stdin);
    return ((float) x) / ((float) UINT32_MAX);
}

int randint(int max) {
    // If max is not a power of 2, this may not be uniform
    uint32_t x;
    fgets((void*) &x, sizeof(uint32_t), stdin);
    return (int) (x % max);
}

// This section makes the rules of the game
pair_t pent[5] = {{0.5, 0.0}, {0.9755282581475768, 0.3454915028125263}, 
                    {0.7938926261462367, 0.9045084971874737}, 
                    {0.2061073738537635, 0.9045084971874737}, 
                    {0.02447174185242318, 0.3454915028125264}};

pair_t hex[6] = {{0.5, 0.0},
                 {0.9330127018922193, 0.25},
                 {0.9330127018922194, 0.7499999999999999},
                 {0.5, 1.0},
                 {0.06698729810778076, 0.7500000000000002},
                 {0.0669872981077807, 0.24999999999999994}};

int number_corners = 6;
pair_t* corns = hex;

int random_corner(int corner) {
    int corner_add = randint(number_corners - 1);
    //if (corner_add == 2) corner_add = 2;
    return (corner + corner_add) % number_corners;
}

pair_t make_pair(float x, float y) {
    pair_t pair = {.x = x, .y = y};
    return pair;
}

pair_t corner_coords(int corner) {
    return corns[corner];
    //float corner_x = corner % 2;
    //float corner_y = corner / 2;
    //return (pair_t) {corner_x, corner_y};
    /*
    switch (corner) {
        case 0:
            return (pair_t) {0, 0.5};
        case 1:
            return (pair_t) {0.5, 0};
        case 2:
            return (pair_t) {1, 0.5};
    }
    return (pair_t) {0.5, 1};
    */
}

int main(int argc, char** argv) {
    if (argc != 2) {
        printf("Needs int argument for size in pixels");
    }
    int size = atoi(argv[1]);
    while (1) {
        float x = better_random();
        float y = better_random();
        int corner = randint(number_corners);
        for (int i = 0; i < 30; i++) {
            corner = random_corner(corner);

            pair_t corner_xy = corner_coords(corner);

            x += (corner_xy.x - x)/2;
            y += (corner_xy.y - y)/2;
            //draw(x * size, y * size);
        }
        draw(x * size, y * size);
    }
}