From 49df2e4de31278d6725c7ab196c4ccfad19c74eb Mon Sep 17 00:00:00 2001
From: Alejandro Laguna <alejandro.laguna@proton.me>
Date: Tue, 14 Jul 2026 18:26:31 +0200
Subject: [PATCH] feat: zoom in and out

---
 src/main.c | 45 ++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 38 insertions(+), 7 deletions(-)

diff --git a/src/main.c b/src/main.c
index 607d64029437c77b4c7b75a0841e723e808eb149..79b5653d52f8253afbb4cd1a3dc0b25ab40a67e3 100644
--- a/src/main.c
+++ b/src/main.c
@@ -12,7 +12,6 @@
 
 // TODO: GPU shadering option
 // TODO: flexible window size
-// TODO: zooming in and out
 // TODO: maybe? change colors
 
 #define WINDOW_TITLE "Mandelbrot Visualization"
@@ -21,14 +20,19 @@
 
 static int points[WINDOW_WIDTH * WINDOW_HEIGHT];
 
-void calculate_points() {
-    double x_min = -2.0, x_max = 1.0;
-    double y_min = -1.2, y_max = 1.2;
+typedef struct position_s {
+    double x_min;
+    double x_max;
+    double y_min;
+    double y_max;
+} position_t;
+
+void calculate_points(position_t* pos) {
     int max_iter = 100;
     for (int py = 0; py < WINDOW_HEIGHT; py++) {
         for (int px = 0; px < WINDOW_WIDTH; px++) {
-            double cr = x_min + (x_max - x_min) * px / (WINDOW_WIDTH - 1);
-            double ci = y_min + (y_max - y_min) * py / (WINDOW_HEIGHT - 1);
+            double cr = pos->x_min + (pos->x_max - pos->x_min) * px / (WINDOW_WIDTH - 1);
+            double ci = pos->y_min + (pos->y_max - pos->y_min) * py / (WINDOW_HEIGHT - 1);
             points[py * WINDOW_WIDTH + px] = mandelbrot_iterations(cr, ci, max_iter);
         }
     }
@@ -66,13 +70,40 @@ int main(void) {
     bool running = true;
     SDL_UpdateWindowSurface(window);
     SDL_ShowWindow(window);
+    position_t position;
+    position.x_min = -2.0;
+    position.x_max = 1.0;
+    position.y_min = -1.2;
+    position.y_max = 1.2;
     while (running) {
         while (SDL_PollEvent(&e)) {
             if (e.type == SDL_EVENT_QUIT) {
                 running = false;
             }
+            if (e.type == SDL_EVENT_MOUSE_WHEEL) {
+                // 1. Get mouse pixel position
+                float mx, my;
+                SDL_GetMouseState(&mx, &my);
+
+                double cr =
+                    position.x_min + (position.x_max - position.x_min) * mx / (WINDOW_WIDTH - 1);
+                double ci =
+                    position.y_min + (position.y_max - position.y_min) * my / (WINDOW_HEIGHT - 1);
+
+                double range_y = position.y_max - position.y_min;
+
+                float factor = (e.wheel.y > 0) ? 0.9f : 1.1f;
+                double new_height = range_y * factor;
+                double aspect = (double)WINDOW_WIDTH / WINDOW_HEIGHT;
+                double new_width = new_height * aspect;
+
+                position.x_min = cr - (double)mx / (WINDOW_WIDTH - 1) * new_width;
+                position.x_max = position.x_min + new_width;
+                position.y_min = ci - (double)my / (WINDOW_HEIGHT - 1) * new_height;
+                position.y_max = position.y_min + new_height;
+            }
         }
-        calculate_points();
+        calculate_points(&position);
         draw_points(surface);
         SDL_UpdateWindowSurface(window);
         SDL_Delay(16);