feat: input class for abstracting SDL_Input functions

engine/CMakeLists.txt

@@ -5,6 +5,8 @@ set(SOURCES
   src/IO/file_manager.cpp
   src/renderer/debug.cpp
 
+  src/input/input.cpp
+
   src/scene/scene.cpp
   src/window/window.cpp
 

engine/include/engine/app/app.h

@@ -3,6 +3,8 @@
 
 #include "engine/scene/scene.h"
 #include "engine/window/event.hpp"
+#include "engine/time/timestep.h"
+
 #include "engine/export.h"
 
 namespace Core {
@@ -11,7 +13,7 @@ namespace Core {
         virtual ~IApplication() = default;
 
         virtual void OnInit(std::shared_ptr<Scene> scene) {};
-        virtual void OnUpdate() {};
+        virtual void OnUpdate(Timestep dt) {};
         virtual void OnShutdown() {};
         
         virtual void OnEvent(const Event& event) {};

engine/include/engine/input/input.h

@@ -0,0 +1,29 @@
+#ifndef ENGINE_INPUT_H_
+#define ENGINE_INPUT_H_
+
+#include <SDL3/SDL.h>
+#include <glm/glm.hpp>
+
+#include "engine/time/timestep.h"
+
+#include "engine/export.h"
+
+namespace Core {
+
+class ENGINE_API Input {
+public:
+    Input() = delete;
+private:
+    friend class Engine;
+    static void Update(Timestep dt);
+public:
+    [[nodiscard]] static glm::vec2 GetRelativeMouse();
+    [[nodiscard]] static bool IsKeyPressed(SDL_Scancode keyCode);
+private:
+    static bool* s_keys_state;
+    static int s_keys_state_size;
+};
+
+}
+
+#endif // ENGINE_INPUT_H_

engine/include/engine/renderer/core.h

@@ -30,6 +30,7 @@ private:
     std::shared_ptr<Window> m_window;
     std::unique_ptr<Renderer> m_renderer;
     std::shared_ptr<Scene> m_scene;
+    uint64_t m_elapsed;
     bool m_running;
 };
 

engine/include/engine/time/timestep.h

@@ -0,0 +1,22 @@
+#ifndef TIME_TIMESTEP_H_
+#define TIME_TIMESTEP_H_
+
+namespace Core {
+    class Timestep {
+    public:
+        Timestep(float time = 0.0f)
+            : m_time(time) {}
+
+        [[nodiscard]] float GetSeconds() const { return m_time; }
+        [[nodiscard]] float GetMilliseconds() const { return m_time * 1000.f; }
+
+        operator float() const { return m_time; }
+    public:
+        static Timestep FromMilliseconds(float milliseconds) { return Timestep(milliseconds * 0.001f); }
+        static Timestep FromSeconds(float seconds) { return Timestep(seconds); }
+    private:
+        float m_time;
+    };
+}
+
+#endif // TIME_TIMESTEP_H_

engine/src/input/input.cpp

@@ -0,0 +1,24 @@
+#include "engine/input/input.h"
+
+namespace Core {
+
+bool* Input::s_keys_state = nullptr;
+int Input::s_keys_state_size = 0;
+
+// Engine only function
+void Input::Update(Timestep dt) {
+    s_keys_state = (bool*)SDL_GetKeyboardState(&s_keys_state_size);
+}
+
+glm::vec2 Input::GetRelativeMouse() {
+    glm::vec2 mouse;
+    SDL_GetRelativeMouseState(&mouse.x, &mouse.y);
+    return mouse;
+}
+
+bool Input::IsKeyPressed(SDL_Scancode keyCode) {
+    assert(keyCode < s_keys_state_size && "Key is out of bounds of the key input state");
+    return s_keys_state[keyCode];
+}
+
+}

engine/src/renderer/core.cpp

@@ -5,6 +5,9 @@
 #include "engine/window/event.hpp"
 #include "engine/renderer/wavefront.h"
 
+#include "engine/time/timestep.h"
+#include "engine/input/input.h"
+
 namespace Core {
 
 Engine* Engine::s_instance = nullptr;
@@ -21,10 +24,19 @@ void Engine::Run(std::unique_ptr<IApplication> app) {
 
     m_window->Subscribe(this);
 
+    uint64_t now = SDL_GetPerformanceCounter();
+    m_elapsed = 0;
+
     while (m_running) {
+        m_elapsed = now;
+        now = SDL_GetPerformanceCounter();
+
+        auto dt = Timestep::FromMilliseconds((float)((now - m_elapsed)*1000 / (float)SDL_GetPerformanceFrequency()));
+
         m_window->ProcessEvents();
 
-        m_app->OnUpdate();
+        Input::Update(dt);
+        m_app->OnUpdate(dt);
 
         m_renderer->Render();
 

sandbox/src/main.cpp

@@ -20,6 +20,7 @@
 #include "engine/components/batch.h"
 
 #include "engine/scene/scene.h"
+#include "engine/input/input.h"
 
 #include "engine/api.h"
 
@@ -83,30 +84,17 @@ public:
         std::cout << "Game initialized" << std::endl;
 
         m_angle = 3.45f;
-        m_lastTicks = SDL_GetTicks();
-
-        m_paused = false;
 
         m_yaw   = -90.0f; // looking along -Z initially
         m_pitch = 0.0f;   // no vertical tilt
-
-        // FPS tracking
-        m_startTicks = SDL_GetTicks();
-        m_frameCount = 0;
     }
 
-    void OnUpdate() override {
-        m_currentTicks = SDL_GetTicks();
-        float deltaTime = static_cast<float>(m_currentTicks - m_lastTicks) / 1000.0f; // seconds
-
-        m_lastTicks = m_currentTicks;
-
-        float mouseXRel, mouseYRel;
-        SDL_GetRelativeMouseState(&mouseXRel, &mouseYRel);
+    void OnUpdate(Timestep dt) override {
+        glm::vec2 mouseRel = Input::GetRelativeMouse();
 
         float sensitivity = 0.1f; // tweak as needed
-        m_yaw   += mouseXRel * sensitivity;
-        m_pitch -= mouseYRel * sensitivity; // invert Y for typical FPS control
+        m_yaw   += mouseRel.x * sensitivity;
+        m_pitch -= mouseRel.y * sensitivity; // invert Y for typical FPS control
 
         // clamp pitch to avoid flipping
         // if (pitch > 89.0f)  pitch = 89.0f;
@@ -122,34 +110,28 @@ public:
 
         glm::vec3 velocity(0.f);
 
-        const bool* state = SDL_GetKeyboardState(nullptr);
-
-        if (state[SDL_SCANCODE_P]) m_paused = !m_paused;
-
         glm::vec3 front = glm::normalize(glm::vec3(cameraViewDirection.x, 0.f, cameraViewDirection.z));
         glm::vec3 right = glm::normalize(glm::cross(front, glm::vec3(0.f, 1.f, 0.f)));
 
-        if (state[SDL_SCANCODE_W]) velocity += front;
-        if (state[SDL_SCANCODE_S]) velocity -= front;
-        if (state[SDL_SCANCODE_A]) velocity -= right;
-        if (state[SDL_SCANCODE_D]) velocity += right;
-        if (state[SDL_SCANCODE_SPACE]) velocity.y += 1.f;
-        if (state[SDL_SCANCODE_LSHIFT]) velocity.y -= 1.f;
+        if (Input::IsKeyPressed(SDL_SCANCODE_W)) velocity += front;
+        if (Input::IsKeyPressed(SDL_SCANCODE_S)) velocity -= front;
+        if (Input::IsKeyPressed(SDL_SCANCODE_A)) velocity -= right;
+        if (Input::IsKeyPressed(SDL_SCANCODE_D)) velocity += right;
+        if (Input::IsKeyPressed(SDL_SCANCODE_SPACE)) velocity.y += 1.f;
+        if (Input::IsKeyPressed(SDL_SCANCODE_LSHIFT)) velocity.y -= 1.f;
 
         auto& camTransform = cameraEntity.GetComponent<transform>();
-        camTransform.position += velocity * deltaTime * 2.5f; // speed is e.g. 2.5f
+        camTransform.position += velocity * (float)dt * 2.5f; // speed is e.g. 2.5f
         camTransform.rotation = cameraViewDirection;
 
         // update rotation
-        if (!m_paused) {
-            m_angle += glm::radians(45.0f) * deltaTime; // 72° per second
+        m_angle += glm::radians(45.0f) * dt; // 72° per second
         if (m_angle > glm::two_pi<float>()) {
             m_angle -= glm::two_pi<float>(); // keep value small
         }
-        }
 
         // ---- Day-night simulation ----
-        m_dayTime += deltaTime;
+        m_dayTime += dt;
         if (m_dayTime > m_dayLength)
             m_dayTime -= m_dayLength; // loop every "day"
 
@@ -181,23 +163,12 @@ public:
             l.intensity = intensity;
         }
 
-        // auto rotateEntts = m_scene->m_registry.view<transform, rotate>();
-        // for (auto [entity, t] : rotateEntts.each()) {
-        //     // auto targetTransform = rotateEntts.get<transform>(entity);
-        //     if (!m_scene->m_registry.all_of<light>(entity)) {
-        //         t.rotation.y = m_angle;
-        //     }
-        // }
+        m_elapsed += dt.GetMilliseconds();
 
-        m_frameCount++;
-        m_currentTicks = SDL_GetTicks();
-        Uint64 elapsed = m_currentTicks - m_startTicks;
-
-        if (elapsed >= 1000) { // one second passed
-            double fps = static_cast<double>(m_frameCount) / (static_cast<double>(elapsed) / 1000.0);
+        if (m_elapsed >= 1000) { // one second passed
+            m_elapsed = 0;
+            double fps = 1 / dt;
             std::cout << "FPS: " << fps << std::endl;
-            m_frameCount = 0;
-            m_startTicks = m_currentTicks;
         }
     }
 
@@ -211,6 +182,9 @@ public:
         }
     }
 private:
+    // for internal 1-second timer
+    int m_elapsed;
+
     std::shared_ptr<Scene> m_scene;
 
     Entity lightEntity;
@@ -218,21 +192,12 @@ private:
     Entity modelEntity;
 
     float m_angle;
-    Uint64 m_lastTicks;
 
     float m_dayTime = 0.0f;       // accumulates time for day-night cycle
     float m_dayLength = 60.0f;    // seconds per full day cycle
 
-    bool m_paused = false;
-
     float m_yaw   = -90.0f; // looking along -Z initially
     float m_pitch = 0.0f;   // no vertical tilt
-
-    // FPS tracking
-    Uint64 m_startTicks;
-    int m_frameCount;
-
-    Uint64 m_currentTicks;
 };
 
 IApplication* CreateApplication() {