From e7f81ff8f43b49331c368e3be09326551e0e6213 Mon Sep 17 00:00:00 2001
From: Alessandro Iezzi <aiezzi@alessandroiezzi.it>
Date: Sat, 17 May 2025 01:16:55 +0200
Subject: Add engine_loop and FPS calculation

---
 src/main/engine/engine.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 src/main/engine/engine.h |  1 +
 src/main/main.c          |  3 +--
 3 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/src/main/engine/engine.c b/src/main/engine/engine.c
index b4b9f42..7752095 100644
--- a/src/main/engine/engine.c
+++ b/src/main/engine/engine.c
@@ -17,6 +17,8 @@
  * along with Tris Game.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <stdio.h>
+#include <time.h>
 #include <GL/gl.h>
 #include "../ui/ui.h"
 
@@ -27,6 +29,17 @@ static float ystep;
 static int width;
 static int height;
 
+typedef struct Engine {
+	void (*draw_frame)();
+} Engine;
+
+static Engine engine;
+
+/* FPS */
+static time_t start;
+static int frames;
+static time_t end;
+
 void
 engine_init(int w, int h)
 {
@@ -47,3 +60,37 @@ engine_draw_line(int x1, int y1, int x2, int y2)
 	glVertex2f(_x1, _y1);
 	glVertex2f(_x2, _y2);
 }
+
+static void
+engine_calculate_fps()
+{
+	frames ++;
+
+	end = time(NULL);
+	if (end - start >= 1.0) {
+		printf("FPS: %d\n", frames);
+		frames = 0;
+		start = time(NULL);
+	}
+}
+
+static void
+draw_frames()
+{
+	engine.draw_frame();
+	engine_calculate_fps();
+}
+
+void
+engine_loop(void (*draw_frame)())
+{
+	engine.draw_frame = draw_frame;
+
+	ui_set_loop_listener(draw_frames);
+
+	/* FPS calculation */
+	start = time(NULL);
+	frames = 0;
+
+	ui_loop();
+}
diff --git a/src/main/engine/engine.h b/src/main/engine/engine.h
index cb9e562..691d8ec 100644
--- a/src/main/engine/engine.h
+++ b/src/main/engine/engine.h
@@ -22,5 +22,6 @@
 
 void engine_init(int width, int height);
 void engine_draw_line(int x1, int y1, int x2, int y2);
+void engine_loop(void (*draw_frame)());
 
 #endif /* __ENGINE_H__ */
diff --git a/src/main/main.c b/src/main/main.c
index 20a2a72..76876f0 100644
--- a/src/main/main.c
+++ b/src/main/main.c
@@ -31,8 +31,7 @@ void draw_frame() {
 int main(void) {
 	engine_init(WIDTH, HEIGHT);
 	ui_set_title("Tris Game");
-	ui_set_loop_listener(draw_frame);
-	ui_loop();
+	engine_loop(draw_frame);
 
 	return EXIT_SUCCESS;
 }
-- 
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