Window / Application

This page covers the main runtime object and the window layer that supports it. In practice, gameplay code normally works through Application, while Window stays as the lower-level runtime wrapper around GLFW and the OpenGL context.

Application

Application owns the engine runtime: window creation, resource loading, camera control, the active scene manager, and the update / render loop.

Lifecycle

Method	What it does
Application(int width, int height, const char *title)	initializes the runtime and creates the window
~Application()	releases the runtime and shuts everything down
Run()	executes the main loop until the window closes
OnUpdate(const std::function<void(float)> &callback)	registers a global per-frame callback

Recommended Use

In a normal game, most gameplay logic should live in scenes. Application::OnUpdate() is best reserved for small global tasks, tools, or special setup that genuinely does not belong to one scene.

Main Frame Order

Run() follows a consistent order every frame:

1. updates Time
2. executes the OnUpdate callback, if one was registered
3. updates the active scene
4. flushes destroyed entities
5. checks global debug input such as collider toggling
6. updates physics
7. updates animation
8. updates particles
9. flushes destroyed entities again
10. renders the world and queued text
11. optionally applies the CRT-style postprocess
12. swaps buffers and polls events
13. captures the next input snapshot

That order matters because it keeps gameplay state, physics, and rendering aligned within the same frame.

Resources

Method	Use
LoadTexture(name, path)	registers a texture under a logical name
LoadFont(name, path, pixelHeight)	registers a font under a logical name
SetDefaultFont(name)	selects a loaded font for DrawText()
SetPostProcessEnabled(enabled)	enables or disables the CRT-style screen pass
IsPostProcessEnabled()	checks the current postprocess state

Behavior Details

Method	Detail
LoadTexture	reuses the texture if the logical name already exists
LoadFont	reuses the font if the logical name already exists
SetDefaultFont	returns false if the font has not been loaded
DrawText	ignores empty strings and queues the command for later rendering

Text

Application::DrawText() does not draw immediately. It queues a text command that is rendered later in the frame, after the world has been drawn.

app.DrawText("Loading...", Vec2(16.0f, 16.0f), Colors::White(), 1.0f, false);

Parameter	Meaning
position	position in logical pixels
color	RGBA tint
scale	scale multiplier applied to the default font
followCamera	true for world text, false for fixed HUD text

Camera

Method	What it does
GetCamera()	returns the main 2D camera
SetCameraPosition()	moves the camera in world space
SetCameraRotation()	rotates the camera around the Z axis
SetCameraProjection()	changes the orthographic bounds
FollowCamera(entity, offset, followRotation, followSpeed)	makes the camera follow an entity
StopCameraFollow()	clears the follow target
IsCameraFollowing()	checks whether a follow target is active
IsPositionOutsideCamera(position, margin)	checks whether a world position is outside the visible camera area
ResetCameraTracking()	restores the default camera state
ShakeCamera(durationSeconds, magnitude, frequency)	adds a short camera shake effect

FollowCamera

Parameter	Default	Notes
offset	(0, 0)	offsets the camera relative to the target
followRotation	false	copies or ignores the target rotation
followSpeed	8.0f	values <= 0 force an instant snap

If the target entity becomes invalid or loses its Transform, the follow is canceled automatically.

IsPositionOutsideCamera() is useful for simple projectile cleanup, culling helper objects, and gameplay logic that should stop caring about things once they are offscreen.

ShakeCamera() is a lightweight screen shake effect for hits, explosions, or boss events. It works on top of the base camera state, so it can be combined with follow camera without replacing it.

Physics and Debug

Method	Use
SetGravity()	changes the global gravity vector
GetGravity()	reads the current gravity vector
SetDebugDrawColliders()	enables collider outlines
IsDebugDrawCollidersEnabled()	checks the current debug state

note

Gravity affects bodies that have Rigidbody::UseGravity = true. Static bodies and top-down actors that do not use gravity are not affected.

Scene and World Access

Method	Returns
GetWorld()	the gameplay World
GetScenes()	the SceneManager

Application is the most convenient entry point from gameplay code because it already exposes the services that scenes normally need.

Window

Window is the lower-level runtime wrapper over GLFW and the OpenGL context.

Method	What it does
Window(width, height, title)	creates the window and context
Update()	swaps buffers and polls events
ShouldClose()	reports whether the user requested the window to close
GetNativeWindow()	returns the underlying GLFWwindow *
GetLogicalWidth() / GetLogicalHeight()	logical rendering resolution
GetFramebufferWidth() / GetFramebufferHeight()	actual drawable size

warning

Creating a Window directly is possible, but most gameplay code should let Application manage it. If GLFW, GLAD, or window creation fails, the constructor throws.

UI

UI is a small static helper that forwards text commands to the active application.

Method	Use
UI::Bind(app)	connects the helper to a running application
UI::Unbind()	clears the bound application
UI::Print(...)	queues text just like Application::DrawText()

When To Use It

• use UI::Print() inside scenes when you do not want to pass Application & around
• use Application::DrawText() if you already have direct access to the application

Example

UI::Print("Score: 10", Vec2(12.0f, 12.0f), Colors::White(), 1.0f, false);

tip

followCamera = false is the right choice for fixed HUD text. Set it to true only if you want the text to move with the world.