Brightness level according to step before excusion

The test to check if something is in the set return -1 else returns the
number of steps, then map the step to a brightness of the pixel.

3 files changed, 16 insertions, 13 deletions

diff --git a/graphics.c b/graphics.c
index 1e7470f..e36fee0 100644
--- a/graphics.c
+++ b/graphics.c
@@ -46,18 +46,21 @@ void graphics_run(GState *state)
 
 static void update(GState *state)
 {
-    SDL_SetRenderDrawColor(state->renderer, 155, 155, 155, SDL_ALPHA_OPAQUE);
+    SDL_SetRenderDrawColor(state->renderer, 0, 0, 0, SDL_ALPHA_OPAQUE);
     SDL_RenderClear(state->renderer);
     for (int x = 0; x < WINDOW_W; x++)
     {
         for (int y = 0; y < WINDOW_H; y++)
         {
-            if (mandelbrot_in_set(map_range((double)x, 0, WINDOW_W, LO, HI)
-                                  + map_range((double)y, 0, WINDOW_H, LO, HI) * I))
-            {
-                SDL_SetRenderDrawColor(state->renderer, 0, 0, 0, SDL_ALPHA_OPAQUE);
-                SDL_RenderDrawPoint(state->renderer, x, y);
-            }
+            double complex mapped_z = map_range((double)x, 0, WINDOW_W, LO, HI)
+                                      + map_range((double)y, 0, WINDOW_H, LO, HI) * I;
+            int steps = mandelbrot_in_set(mapped_z);
+            if (steps == -1)
+                continue;
+            double brightness = map_range(steps, LO, HI, 0, 20);
+            SDL_SetRenderDrawColor(state->renderer, brightness, brightness,
+                                   brightness, SDL_ALPHA_OPAQUE);
+            SDL_RenderDrawPoint(state->renderer, x, y);
         }
     }
     SDL_RenderPresent(state->renderer);
diff --git a/header.h b/header.h
index 97e3de6..8873077 100644
--- a/header.h
+++ b/header.h
@@ -13,8 +13,8 @@
 # define AXIS_DIV 46.0
 # define AXIS_STEP ((HI - LO) / AXIS_DIV)
 
-# define MAX_ITERATION 50
-# define _INFINITY 15
+# define MAX_ITERATION 30
+# define _INFINITY 4
 
 
 typedef struct
@@ -31,7 +31,7 @@ typedef struct
 } GConf;
 
 // mandelbrot.c
-double mandelbrot_in_set(double _Complex c);
+int mandelbrot_in_set(double _Complex c);
 void mandelbrot_print(void);
 
 // graphics.c
diff --git a/mandelbrot.c b/mandelbrot.c
index c5f5148..48d893d 100644
--- a/mandelbrot.c
+++ b/mandelbrot.c
@@ -6,7 +6,7 @@
 #define IN_CHAR '*'
 #define OUT_CHAR ' '
 
-double mandelbrot_in_set(double complex c)
+int mandelbrot_in_set(double complex c)
 {
     int i;
     double complex z = 0;
@@ -14,9 +14,9 @@ double mandelbrot_in_set(double complex c)
     {
         z = cpow(z, 2) + c;
         if (cabs(z) > _INFINITY)
-            return 0;
+            return i;
     }
-    return 1;
+    return -1;
 }
 
 void mandelbrot_print(void)