Crude Chaos Game For Rick

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <cairo/cairo.h>


#define PI 3.141592653589793
#define PI2 (PI * 2.0)
#define BASE_POINTS 3
#define SCALE 0.5
#define IMAX 100000
#define RAND_MOD(mp_mod) (rand() % (mp_mod))
#define RAND_FLOAT() (rand() / (RAND_MAX - 0.0))


struct point2d
{
    double x;
    double y;
};

struct color
{
    double r;
    double b;
    double g;
    double a;
};


void
render_circle(
    cairo_t* const cr,
struct point2d cp,
    double r,
struct color c
    ) {
    cairo_new_path(cr);
    cairo_arc(cr, cp.x, cp.y, r, 0, PI2);
    cairo_set_source_rgba(cr, c.r, c.g, c.b, c.a);
    cairo_set_line_width(cr, 1.0);
    cairo_stroke(cr);
}


struct point2d
    get_scaled_point(
struct point2d p0,
struct point2d p1,
    double scale
    ) {
    struct point2d spt = {
        p0.x + (p1.x - p0.x) * scale,
        p0.y + (p1.y - p0.y) * scale
    };

    return spt;
}


void
chaos_game_init(
struct point2d* result,
    size_t depth
    ) {
    double astep = PI2 / depth;

    for (size_t i = 0; i < depth; ++i)
    {
        double angle = astep * i;

        result[i].x = cos(angle);
        result[i].y = sin(angle);
    }
}


void
chaos_game_plot(
    cairo_t* const cr,
struct point2d origin,
    double radius,
struct point2d* points,
    size_t depth,
    size_t imax,
    double scale
    ) {
    struct point2d z = {
        -1.0 + RAND_FLOAT(),
        -1.0 + RAND_FLOAT()
    };

    for (size_t i = 0; i < imax + 100; ++i)
    {
        struct point2d* rpt = &points[RAND_MOD(depth)];
        struct point2d npt = get_scaled_point(*rpt, z, scale);

        struct point2d ppt = {
            npt.x * radius + origin.x,
            npt.y * radius + origin.y
        };

        if (i >= 100)
        {
            render_circle(cr, ppt, 1.0, (struct color) { 1.0, 1.0, 1.0, 1.0 });
        }

        printf("computing iteration: %lu of %lu\r", (unsigned long)i, (unsigned long)(imax + 100));

        z = npt;
    }

    puts("\nComplete!");
}




#define OUTPUT "C:\\Users\\Chris\\Desktop\\ct_crude_chaos_game_p0.png"

int main(void)
{
    srand(12345678);

    {
        unsigned int width = 640;
        unsigned int height = 640;

        cairo_surface_t *surface = NULL;
        cairo_t *cr = NULL;

        surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
        cr = cairo_create(surface);

        cairo_rectangle(cr, 0.0, 0.0, width, height);
        cairo_set_source_rgba(cr, 0.0, 0.0, 0.0, 1.0);
        cairo_fill(cr);

        {
            struct point2d points[BASE_POINTS] = { { 0.0 } };
            struct point2d origin = { width / 2.0, height / 2.0 };
            double radius = (height / 2.0) - 2.0;

            render_circle(
                cr,
                origin,
                radius,
                (struct color) {
                1.0, 0.0, 0.0, 1.0
            }
            );

            chaos_game_init(points, BASE_POINTS);
            chaos_game_plot(cr, origin, radius, points, BASE_POINTS, IMAX, SCALE);
        }

        cairo_surface_write_to_png(surface, OUTPUT);
        cairo_destroy(cr);
        cairo_surface_destroy(surface);

        //system("mspaint " OUTPUT);
    }

    //puts("\nProgram Complete!");
    //getchar();

    return 0;
}