Exposes time object and control

include/flip/application.h

@@ -6,7 +6,8 @@
 // flip::Application implementation.
 namespace flip {
 class Application;
-}
+struct Time;
+}  // namespace flip
 extern std::unique_ptr<flip::Application> InstantiateApplication();
 
 // Sokol forward declaration
@@ -41,7 +42,7 @@ class Application {
  private:
   virtual bool Initialize(bool _headless) { return true; }
 
-  virtual LoopControl Update(float _time, float _dt, float _inv_dt) {
+  virtual LoopControl Update(const Time& _time) {
     return LoopControl::kContinue;
   }
 

include/flip/camera.h

@@ -7,6 +7,8 @@ struct sapp_event;
 
 namespace flip {
 
+struct Time;
+
 // Camera view parameters, passed to the renderer.
 struct CameraView {
   float fov;
@@ -19,7 +21,7 @@ class Camera {
  public:
   virtual ~Camera() = default;
 
-  virtual bool Update(float _time, float _dt, float _inv_dt) { return true; }
+  virtual bool Update(const Time& _time) { return true; }
   virtual bool Event(const sapp_event& _event) { return false; }
   virtual bool Menu() { return true; }
 

include/flip/utils/time.h

@@ -0,0 +1,35 @@
+#pragma once
+
+namespace flip {
+
+struct Time {
+  float elapsed;
+  float dt;
+  float inv_dt;
+};
+
+class TimeControl {
+ public:
+  Time Update(float _dt);
+
+  bool Gui();
+
+ private:
+  // Current time, including scaling and freezes..
+  float elapsed_ = 0.f;
+
+  // Update time scale factor.
+  float scale_ = 1;
+
+  // Update time freeze state.
+  bool freeze_ = false;
+
+  // Fixed update rate, only applies to application update dt, not the real fps.
+  const float kFixedRateDefault = 60.f;
+  float fixed_rate_ = kFixedRateDefault;
+
+  // Fixes update rat to a fixed value, instead of real_time.
+  bool fix_rate_ = false;
+};
+
+}  // namespace flip

samples/imdraw/main.cpp

@@ -2,20 +2,22 @@
 
 #include "flip/application.h"
 #include "flip/imdraw.h"
+#include "flip/utils/time.h"
 
 // Implement the minimal flip::Application.
 class ImDraw : public flip::Application {
  public:
   ImDraw() : flip::Application(Settings{.title = "ImDraw"}) {}
 
  private:
-  virtual LoopControl Update(float _time, float _dt, float _inv_dt) override {
-    transform1_ = HMM_Rotate_RH(_time, HMM_Vec3{0, 1, 0}) *
+  virtual LoopControl Update(const flip::Time& _time) override {
+    auto elapsed = _time.elapsed;
+    transform1_ = HMM_Rotate_RH(elapsed, HMM_Vec3{0, 1, 0}) *
                   HMM_Translate(HMM_Vec3{0, 6, 0}) *
-                  HMM_Rotate_RH(HMM_PI / 4,
-                                HMM_Vec3{std::cos(_time), std::sin(_time), 0}) *
+                  HMM_Rotate_RH(HMM_PI / 4, HMM_Vec3{std::cos(elapsed),
+                                                     std::sin(elapsed), 0}) *
                   HMM_Scale(HMM_Vec3{3, 3, 3});
-    transform2_ = transform1_ * HMM_Rotate_RH(_time, HMM_Vec3{0, 1, 0});
+    transform2_ = transform1_ * HMM_Rotate_RH(elapsed, HMM_Vec3{0, 1, 0});
 
     return LoopControl::kContinue;
   }

samples/input/main.cpp

@@ -8,7 +8,7 @@ class Input : public flip::Application {
   Input() : flip::Application(Settings{.title = "Input"}) {}
 
  private:
-  virtual LoopControl Update(float _time, float _dt, float _inv_dt) override {
+  virtual LoopControl Update(const flip::Time& _time) override {
     if (keyboard_[SAPP_KEYCODE_Q].released()) {
       return LoopControl::kBreak;
     }

src/CMakeLists.txt

@@ -11,6 +11,7 @@ add_library(flip
   ${PROJECT_SOURCE_DIR}/include/flip/utils/loader.h
   ${PROJECT_SOURCE_DIR}/include/flip/utils/profile.h
   ${PROJECT_SOURCE_DIR}/include/flip/utils/sokol_gfx.h
+  ${PROJECT_SOURCE_DIR}/include/flip/utils/time.h
   application.cpp
   impl/imdrawer.h
   impl/imdrawer.cpp
@@ -28,6 +29,7 @@ add_library(flip
   utils/keyboard.cpp
   utils/loader.cpp
   utils/profile.cpp
-  utils/sokol_gfx.cpp)
+  utils/sokol_gfx.cpp
+  utils/time.cpp)
 target_include_directories(flip PUBLIC ${PROJECT_SOURCE_DIR}/include)
 target_link_libraries(flip sokol hmm stb_image)

src/application.cpp

@@ -8,6 +8,7 @@
 #include "flip/camera.h"
 #include "flip/renderer.h"
 #include "flip/utils/profile.h"
+#include "flip/utils/time.h"
 #include "impl/factory.h"
 
 // Sokol library
@@ -138,22 +139,21 @@ class ApplicationCb {
     sfetch_dowork();
 
     // Updates time.
-    const auto dt = static_cast<float>(stm_sec(stm_laptime(&last_time_)));
-    const auto inv_dt = dt == 0.f ? 0.f : (1.f / dt);
-    const auto time = static_cast<float>(stm_sec(last_time_));
-    profile_frame_.push(dt * 1e3f);
+    const auto sys_dt = static_cast<float>(stm_sec(stm_laptime(&last_time_)));
+    profile_frame_.push(sys_dt * 1e3f);
+    const auto time = time_control_.Update(sys_dt);
 
     {  // Updates application
       Profile profile(profile_update_);
-      const auto control = application_->Update(time, dt, inv_dt);
+      const auto control = application_->Update(time);
       success &= control != Application::LoopControl::kBreakFailure;
       exit = control != Application::LoopControl::kContinue;
     }
 
     // Renders application
     if (!headless_) {
       Profile profile(profile_render_);
-      success &= Display(time, dt, inv_dt);
+      success &= Display(time);
     }
 
     // Manages exit
@@ -162,11 +162,11 @@ class ApplicationCb {
     }
   }
 
-  bool Display(float _time, float _dt, float _inv_dt) {
+  bool Display(const Time& _time) {
     assert(!headless_);
 
     bool success = true;
-    success &= camera_->Update(_time, _dt, _inv_dt);
+    success &= camera_->Update(_time);
 
     {  // Default Rendering pass raii
       auto pass = Renderer::DefaultPass(*renderer_, camera_->GetCameraView());
@@ -208,18 +208,16 @@ class ApplicationCb {
       plot("Frame", profile_frame_);
     };
 
-    static bool pop_up = false;
     if (ImGui::BeginMenu("Performance")) {
-      ImGui::MenuItem("Pop up", 0, &pop_up);
-      plot_all();
-      ImGui::EndMenu();
-    }
-    if (pop_up) {
-      ImGui::SetNextWindowSize(ImVec2(240, 320), ImGuiCond_Once);
-      if (ImGui::Begin("Performance", &pop_up, 0)) {
+      if (ImGui::TreeNodeEx("Time control")) {
+        time_control_.Gui();
+        ImGui::TreePop();
+      }
+      if (ImGui::TreeNodeEx("Performance")) {
         plot_all();
+        ImGui::TreePop();
       }
-      ImGui::End();
+      ImGui::EndMenu();
     }
     return true;
   }
@@ -243,6 +241,7 @@ class ApplicationCb {
   ProfileRecord profile_frame_;
 
   // Time management
+  TimeControl time_control_;
   uint64_t last_time_ = 0;
 
   // Does application has a windows (head)

src/impl/orbit_camera.cpp

@@ -9,7 +9,7 @@
 
 namespace flip {
 
-bool OrbitCamera::Update(float _time, float _dt, float _inv_dt) {
+bool OrbitCamera::Update(const Time& _time) {
   bool success = true;
 
   // Camera to eye vector

src/impl/orbit_camera.h

@@ -11,7 +11,7 @@ class OrbitCamera : public Camera {
   virtual ~OrbitCamera() = default;
 
  protected:
-  virtual bool Update(float _time, float _dt, float _inv_dt) override;
+  virtual bool Update(const Time& _time) override;
   virtual bool Event(const sapp_event& _event) override;
   virtual bool Menu() override;
 

src/utils/time.cpp

@@ -0,0 +1,39 @@
+#include "flip/utils/time.h"
+
+#include "imgui/imgui.h"
+
+namespace flip {
+
+Time TimeControl::Update(float _dt) {
+  auto dt = 0.f;
+  if (!freeze_) {
+    if (fix_rate_) {
+      dt = scale_ / fixed_rate_;
+    } else {
+      dt = _dt * scale_;
+    }
+  }
+  elapsed_ += dt;
+
+  return {elapsed_, dt, dt == 0.f ? 0.f : (1.f / dt)};
+}
+
+bool TimeControl::Gui() {
+  ImGui::Checkbox("Freeze", &freeze_);
+  ImGui::SameLine();
+  ImGui::Checkbox("Fix update rate", &fix_rate_);
+  if (ImGui::Button("Reset")) {
+    fixed_rate_ = kFixedRateDefault;
+    scale_ = 1.f;
+  }
+  ImGui::SameLine();
+  if (fix_rate_) {
+    ImGui::SliderFloat("Update rate", &fixed_rate_, 1.f, 200.f, "%.2f fps");
+  } else {
+    ImGui::SliderFloat("Time scale", &scale_, -10.f, 10.f, "%.2f",
+                       ImGuiSliderFlags_Logarithmic);
+  }
+  return true;
+}
+
+}  // namespace flip