Supersampling

- Random supersampling (prettier but quite slow)
- WIP: bette color gradient

1 files changed, 32 insertions, 4 deletions

diff --git a/mandelbrot.c b/mandelbrot.c
index 1112575..7017a54 100644
--- a/mandelbrot.c
+++ b/mandelbrot.c
@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <math.h>
 #include <pthread.h>
 #include "header.h"
 
@@ -9,6 +10,7 @@
 #define AXIS_DIV 46.0
 #define REAL_AXIS_STEP ((PRINT_REAL_HI - PRINT_REAL_LO) / AXIS_DIV)
 #define IMAG_AXIS_STEP ((PRINT_IMAG_HI - PRINT_IMAG_LO) / AXIS_DIV)
+#define SAMPLES 1
 
 #define IN_CHAR '*'
 #define OUT_CHAR ' '
@@ -37,6 +39,16 @@ int mandelbrot_in_set(double ca, double cb)
     return n;
 }
 
+
+int mandelbrot_in_set_super_sampled(double ca, double cb, double real_step, double imag_step)
+{
+    int total = 0;
+    for (int i = 0; i < SAMPLES; i++)
+        total += mandelbrot_in_set(ca - (double_rand() * real_step) / 2,
+                                   cb - (double_rand() * imag_step) / 2);
+    return total / SAMPLES;
+}
+
 void *mandelbrot_pixels(double real_lo, double real_hi, double imag_lo,
                         double imag_hi, int width, int height, Color *palette)
 {
@@ -55,6 +67,7 @@ void *mandelbrot_pixels(double real_lo, double real_hi, double imag_lo,
         args->real_hi = real_hi;
         args->width = width;
         args->imag = map_range((double)y, 0, height, imag_lo, imag_hi);
+        args->imag_step = (imag_hi - imag_lo) / (0.5 + (height - 1));
         args->palette = palette;
         args->row = pixels + PIXELS_CHANELS * width * y;
         pthread_create(&threads[y], NULL, pixel_row, args);
@@ -68,13 +81,28 @@ void *mandelbrot_pixels(double real_lo, double real_hi, double imag_lo,
 static void *pixel_row(void *void_args)
 {
     ThreadArgs *args = (ThreadArgs*)void_args;
+    int iterations;
+    double real_step = (args->real_hi - args->real_lo) / (0.5 + (args->width - 1));
     for (int x = 0; x < args->width; x++)
     {
         double a = map_range((double)x, 0, args->width, args->real_lo, args->real_hi);
-        Color color = args->palette[mandelbrot_in_set(a, args->imag)];
-        args->row[x * PIXELS_CHANELS] = color.rgb.r;
-        args->row[x * PIXELS_CHANELS + 1] = color.rgb.g;
-        args->row[x * PIXELS_CHANELS + 2] = color.rgb.b;
+        if (SAMPLES == 1)
+            iterations = mandelbrot_in_set(a, args->imag);
+        else
+        {
+            iterations = mandelbrot_in_set_super_sampled(
+                a, args->imag, real_step, args->imag_step);
+        }
+
+        /* double logBase = 1.0 / log(2.0); */
+        /* double logHalfBase = log(0.5) * logBase; */
+        /* int color_index = (int)(5 + iterations - logHalfBase */
+        /*                   - log(log(a * a + args->imag * args->imag)) * logBase); */
+        Color color = args->palette[iterations];
+        int row_index = x * PIXELS_CHANELS;
+        args->row[row_index] = color.rgb.r;
+        args->row[row_index + 1] = color.rgb.g;
+        args->row[row_index + 2] = color.rgb.b;
     }
     free(args);
     return NULL;