From c055eeef6d41269d11b2ddf7f9aba6f8867da65d Mon Sep 17 00:00:00 2001
From: Nikita Kostovsky <nikita@kostovsky.me>
Date: Tue, 23 Dec 2025 15:28:05 +0100
Subject: initial commit

---
 core/src/cpp/fps_counter.cpp | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 core/src/cpp/fps_counter.cpp

(limited to 'core/src/cpp/fps_counter.cpp')

diff --git a/core/src/cpp/fps_counter.cpp b/core/src/cpp/fps_counter.cpp
new file mode 100644
index 0000000..fe4233d
--- /dev/null
+++ b/core/src/cpp/fps_counter.cpp
@@ -0,0 +1,41 @@
+#include "fps_counter.h"
+
+#include <SDL_render.h>
+
+FPS_Counter::FPS_Counter(SDL_Renderer* renderer)
+    // TODO: cleanup fucking hardcode everywhere
+    : renderer{renderer}
+    , numbers{renderer, "numbers.bmp", 24}
+{
+}
+
+void FPS_Counter::draw()
+{
+    fps_cur++;
+
+    double dt = std::chrono::duration<double>(Clock::now() - timestamp).count();
+
+    // update current FPS reading every 300 ms
+    // TODO: rewrite with type safety
+    if (dt >= .3)
+    {
+        fps_prev = fps_cur / dt;
+        fps_cur = 0;
+        timestamp = Clock::now();
+    }
+
+    // first character will be drawn here
+    SDL_Rect dst = {4, 16, numbers.width, numbers.height};
+
+    // extract individual digits of fps_prev
+    for (const char c : std::to_string(fps_prev))
+    {
+        // crude conversion of numeric characters to int: '7'-'0'=7
+        SDL_Rect src = numbers.rect(c - '0');
+        // draw current digit
+        SDL_RenderCopy(renderer, numbers.texture, &src, &dst);
+        // draw characters left-to-right, +4 for letter spacing
+        // TODO: add padding directly to the .bmp file
+        dst.x += numbers.width + 4;
+    }
+}
-- 
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