restructure into src/

src/mandelbrot.c

@@ -0,0 +1,107 @@
+#include "stdio.h"
+#include "math.h"
+#include "stdint.h"
+#include "stdbool.h"
+
+#define MAX_DEPTH 50
+#define WIDTH 420
+#define HEIGHT 360
+
+#define X_MIN -2.0
+#define X_MAX 1.1
+#define Y_MIN -1.3
+#define Y_MAX 1.3
+
+#define SIZE (WIDTH * HEIGHT)
+
+typedef struct Complex {
+  double real, imag;
+} Complex;
+
+typedef struct Color {
+  uint8_t r, g, b;
+} Color;
+
+int diverge(Complex c);
+Color color_map(int depth);
+void write_ppm(char *path, Color img[SIZE]);
+
+int main() {
+  Color img[SIZE];
+  for (int i = 0; i < HEIGHT; i++) {
+    for (int j = 0; j < WIDTH; j++) {
+      double x = ((double)j / (double)WIDTH) * (X_MAX - X_MIN) + X_MIN;
+      double y = ((double)i / (double)HEIGHT) * (Y_MAX - Y_MIN) + Y_MIN;
+      Complex c = {.real = x, .imag = y};
+      int depth = diverge(c);
+      img[i * WIDTH + j] = color_map(depth);
+    }
+  }
+  write_ppm("out/c.ppm", img);
+
+  return 1;
+}
+
+/////////////////////
+// complex numbers //
+/////////////////////
+
+void cx_print(Complex z) {
+  printf("%f + %f i\n", z.real, z.imag);
+}
+
+static inline Complex cx_square(Complex z) {
+  return (Complex){z.real * z.real - z.imag * z.imag, 2 * z.real * z.imag};
+}
+
+static inline Complex cx_add(Complex z1, Complex z2) {
+  return (Complex){z1.real + z2.real, z1.imag + z2.imag};
+}
+
+static inline double cx_abs(Complex z) {
+  return sqrt(z.real * z.real + z.imag * z.imag);
+}
+
+////////////////
+// mandelbrot //
+////////////////
+
+static inline Complex f(Complex z, Complex c) {
+  return cx_add(cx_square(z), c);
+}
+
+// return iteration count, MAX_DEPTH if diverge
+int diverge(Complex c) {
+  int depth = 0;
+  Complex z = {0.0, 0.0};
+  while (depth < MAX_DEPTH) {
+    z = f(z, c);
+    if (cx_abs(z) > 2)
+      return depth;
+    depth++;
+  }
+  return MAX_DEPTH;
+}
+
+Color color_map(int depth) {
+  bool cond = depth % 2 == 0;
+  return (Color){
+    cond ? 255 : 0,
+    cond ? 255 : 0,
+    cond ? 255 : 0
+  };
+}
+
+////////////////
+// ppm-writer //
+////////////////
+
+void write_ppm(char *path, Color img[SIZE]) {
+  FILE *fptr;
+  fptr = fopen(path, "w");
+  fprintf(fptr, "P3\n%d %d\n255\n", WIDTH, HEIGHT);
+  for (int i = 0; i < SIZE; i++)
+    fprintf(fptr, "%d %d %d\n", img[i].r, img[i].g, img[i].b);
+  printf("successfully wrote to %s\n", path);
+  fclose(fptr);
+}

src/mandelbrot.janet

@@ -0,0 +1 @@
+(print "hello world")