functioning

1 files changed, 316 insertions, 0 deletions

diff --git a/mandelbrot_set.c b/mandelbrot_set.c
new file mode 100644
index 0000000..4420372
--- /dev/null
+++ b/mandelbrot_set.c
@@ -0,0 +1,316 @@
+#include <complex.h>
+#include <math.h>
+#include <ncurses.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#define INITIAL_WIDTH 3.2L
+#define INITIAL_ITERATIONS 100
+#define MAX_ITERATIONS 100000
+#define FRAME_DELAY 30000 // in microseconds
+#define ZOOM_RATE 0.965L
+
+static const char gradient[] = " .,:;irsXA253hMHGS#9B&@";
+
+struct viewer {
+	long double center_x;
+	long double center_y;
+	long double width;
+	long double target_x;
+	long double target_y;
+	long double zoom_rate;
+	size_t max_iterations;
+	bool paused;
+	bool show_status;
+};
+
+static int mandelbrot(long double cr, long double ci, size_t max_iterations);
+
+static char iteration_character(size_t iteration, size_t max_iterations);
+
+static void reset_viewer(struct viewer *viewer);
+
+static void initialize_viewer(struct viewer *viewer);
+
+static void update_zoom(struct viewer *viewer);
+
+static void draw_status(const struct viewer *viewer, int rows, int columns);
+
+static void draw_mandelbrot(const struct viewer *viewer);
+
+static void move_view(struct viewer *viewer, long double dx, long double dy);
+
+static bool handle_input(struct viewer *viewer);
+
+int main(void)
+{
+	struct viewer viewer;
+	bool running = true;
+
+	initialize_viewer(&viewer);
+
+	if (initscr() == NULL) {
+		fprintf(stderr, "Failed to init ncurses");
+		return -1;
+	}
+
+	cbreak();
+	noecho();
+	keypad(stdscr, true);
+	nodelay(stdscr, true);
+	curs_set(0);
+
+	while (running) {
+		draw_mandelbrot(&viewer);
+		running = handle_input(&viewer);
+		update_zoom(&viewer);
+		usleep(FRAME_DELAY);
+	}
+
+	endwin();
+	return 0;
+}
+
+static int mandelbrot(long double cr, long double ci, size_t max_iterations)
+{
+	long double zr = 0.0L;
+	long double zi = 0.0L;
+	size_t iteration;
+
+	for (iteration = 0; iteration < max_iterations; iteration++) {
+		long double zr2 = zr * zr;
+		long double zi2 = zi * zi;
+
+		if (zr2 + zi2 > 4.0) {
+			break;
+		}
+
+		zi = 2.0 * zr * zi + ci;
+		zr = zr2 - zi2 + cr;
+	}
+
+	return iteration;
+}
+
+static char iteration_character(size_t iteration, size_t max_iterations)
+{
+	size_t gradient_length = sizeof(gradient) - 2;
+	size_t index;
+
+	if (iteration >= max_iterations) {
+		return ' ';
+	}
+
+	// selecting the character
+	index = iteration * gradient_length / max_iterations;
+
+	if (index > gradient_length) {
+		index = gradient_length;
+	}
+
+	return gradient[index];
+}
+
+static void reset_viewer(struct viewer *viewer)
+{
+	viewer->center_x = 0.0L;
+	viewer->center_y = 0.0L;
+	viewer->width = INITIAL_WIDTH;
+	viewer->max_iterations = INITIAL_ITERATIONS;
+}
+
+static void initialize_viewer(struct viewer *viewer)
+{
+	reset_viewer(viewer);
+	viewer->target_x = -0.743643887037151L;
+	viewer->target_y = 0.131825904205330L;
+	viewer->zoom_rate = ZOOM_RATE;
+	viewer->paused = false;
+	viewer->show_status = true;
+}
+
+static void update_zoom(struct viewer *viewer)
+{
+	if (viewer->paused) {
+		return;
+	}
+
+	// scales movement magnitude based on zoom rate so camera is always in
+	// real center,
+	// i.e. the more zoomed in the smaller movements become
+	long double movement = 1.0L - viewer->zoom_rate;
+
+	viewer->center_x += (viewer->target_x - viewer->center_x) * movement;
+	viewer->center_y += (viewer->target_y - viewer->center_y) * movement;
+	viewer->width *= viewer->zoom_rate;
+
+	// increases number of iterations as zoom increases to see finer detail
+	viewer->max_iterations =
+	    INITIAL_ITERATIONS +
+	    (int)(40.0L * logl(INITIAL_WIDTH / viewer->width));
+
+	if (viewer->max_iterations > MAX_ITERATIONS)
+		viewer->max_iterations = MAX_ITERATIONS;
+
+	if (viewer->width < 1.0e-16L)
+		reset_viewer(viewer);
+}
+
+static void draw_status(const struct viewer *viewer, int rows, int columns)
+{
+
+	if (!viewer->show_status || rows < 2) {
+		return;
+	}
+
+	char status[256];
+	snprintf(status, sizeof(status),
+		 "center %.18Lf %+.18Lfi  width %.3Le  iter %zu  %s",
+		 viewer->center_x, viewer->center_y, viewer->width,
+		 viewer->max_iterations,
+		 viewer->paused ? "PAUSED" : "AUTO ZOOM");
+
+	attron(A_REVERSE);
+	mvaddnstr(0, 0, status, columns);
+
+	// fill rest of row with spaces
+	for (int column = (int)strlen(status); column < columns; column++) {
+		mvaddch(0, column, ' ');
+	}
+	attroff(A_REVERSE);
+}
+
+static void draw_mandelbrot(const struct viewer *viewer)
+{
+	size_t rows;
+	size_t columns;
+
+	getmaxyx(stdscr, rows, columns);
+
+	// if status bar is on -> start row is 1 not 0
+	int start_row = viewer->show_status ? 1 : 0;
+
+	if (rows - start_row <= 0 || columns <= 0) {
+		return;
+	}
+
+	long double height = viewer->width * (long double)(rows - start_row) /
+			     (long double)columns * 2.0L;
+
+	erase();
+
+	for (int screen_y = start_row; screen_y < rows; screen_y++) {
+		long double normalized_y = (long double)(screen_y - start_row) /
+					   (long double)(rows - start_row - 1);
+
+		long double ci =
+		    viewer->center_y + (normalized_y - 0.5L) * height;
+
+		for (int screen_x = 0; screen_x < columns; screen_x++) {
+			long double normalized_x =
+			    (long double)screen_x / (long double)(columns - 1);
+
+			long double cr = viewer->center_x +
+					 (normalized_x - 0.5L) * viewer->width;
+
+			int iteration =
+			    mandelbrot(cr, ci, viewer->max_iterations);
+
+			char pixel = iteration_character(
+			    iteration, viewer->max_iterations);
+
+			mvaddch(screen_y, screen_x, pixel);
+		}
+	}
+
+	draw_status(viewer, rows, columns);
+	refresh();
+}
+
+static void move_view(struct viewer *viewer, long double dx, long double dy)
+{
+	long double height = viewer->width * 0.5L;
+
+	viewer->center_x += viewer->width * dx;
+	viewer->center_y += height * dy;
+	viewer->target_x += viewer->width * dx;
+	viewer->target_y += height * dy;
+}
+
+static bool handle_input(struct viewer *viewer)
+{
+	int key = getch();
+
+	switch (key) {
+	case 'q':
+	case 'Q':
+		return false;
+
+	case ' ':
+	case 'p':
+	case 'P':
+		viewer->paused = !viewer->paused;
+		break;
+
+	case 'r':
+	case 'R':
+		reset_viewer(viewer);
+		break;
+
+	case 's':
+	case 'S':
+		viewer->show_status = !viewer->show_status;
+		break;
+
+	case '+':
+	case '=':
+		viewer->width *= 0.8L;
+		break;
+
+	case '-':
+	case '_':
+		viewer->width *= 1.25L;
+		break;
+
+	case KEY_LEFT:
+	case 'h':
+		move_view(viewer, -0.1L, 0.0L);
+		break;
+
+	case KEY_RIGHT:
+	case 'l':
+		move_view(viewer, 0.1L, 0.0L);
+		break;
+
+	case KEY_UP:
+	case 'k':
+		move_view(viewer, 0.0L, -0.1L);
+		break;
+
+	case KEY_DOWN:
+	case 'j':
+		move_view(viewer, 0.0L, 0.1L);
+		break;
+
+	case '[':
+		viewer->zoom_rate -= 0.005L;
+		if (viewer->zoom_rate < 0.8L)
+			viewer->zoom_rate = 0.8L;
+		break;
+
+	case ']':
+		viewer->zoom_rate += 0.005L;
+		if (viewer->zoom_rate > 0.999L)
+			viewer->zoom_rate = 0.999L;
+		break;
+
+	default:
+		break;
+	}
+
+	return true;
+}