Event horizon

event_horizon.c

#include <stdio.h>
#include <math.h>

#define WIDTH 30
#define HEIGHT 30

int main() {
    float w = WIDTH;
    float h = HEIGHT;

    for (int col = 0; col < HEIGHT; ++col) {
        for (int row = 0; row < WIDTH; ++row) {
            float x = col;
            float y = row;
            float cx = (2 * x - w) / h;
            float cy = (2 * y - h) / h;
            float d = sqrtf(cx * cx + cy * cy);
            d -= 0.5;
            d += 0.01 * h / (2 * (x - y) + h - w);
            d = fabsf(d);
            d = 0.1 / d;
            char c = " -+=<@#"[(int)floorf(d / (1 + d) * 7)];
            printf("%c%c", c, c);
        }
        printf("\n");
    }

    return 0;
}