undeadbytes

Camera

The Camera class is designed to manage the rendering and viewport of the game world. It focuses on controlling the visible area based on the position of the player and efficiently rendering only the visible portion of the game world.

Properties

• x, y: Current position of the camera in the game world.
• offsetX, offsetY: Offsets used for adjusting rendering position.
• context: Rendering context, typically a 2D canvas rendering context.
• frames: Counter to control the frequency of updates.
• screen: Object representing the visible screen or viewport.

Methods

Constructor

constructor(context, frames = 0)

Initializes the Camera instance with an initial position, rendering context, and an optional number of frames (default is 0).

• context (CanvasRenderingContext2D): The rendering context of the HTML5 canvas.
• frames (number, optional): The initial frame count, defaults to 0.

update

update(player, entities)

Called to update the camera’s state. It increments the frame counter and, when reaching a certain threshold, calculates the new screen object based on the player’s position and the canvas dimensions. It checks each entity’s bounding box or bounding circle against the screen to determine if they are within the visible area. Entities outside the visible area are flagged as sleep.

resize

resize()

A placeholder method for handling resizing of the viewport. Currently empty and can be extended for specific resizing behavior.

newScene

newScene()

Clears the rendering context to prepare for rendering a new scene.

preRender

preRender(entity)

Takes an entity as a parameter and adjusts the camera’s position based on the entity’s position. It calculates the offset needed to center the entity on the screen and applies a translation to the rendering context to simulate camera movement.

postRender

postRender()

Restores the rendering context to its previous state after rendering.

Dependencies

• Collision Class: The Collision class from '../Collision' is imported for collision detection, specifically for checking if entities are within the visible screen ( entity.sleep = ! Collision.intersection(bounds, this.screen)).

• Configuration Object: The config object from '../../config' is imported. It contains constants including the size of game world cells.

Conclusion

1. The update method is called regularly within the game loop to manage the camera state.
2. It increments the frame counter and, when reaching a threshold, updates the visible screen.
3. It checks each entity against the visible screen and marks entities outside the screen as sleep.
4. The preRender method is used before rendering each entity, adjusting the camera’s position based on the player’s position.
5. The postRender method is used after rendering each entity to restore the rendering context.

This Camera class provides a flexible and efficient way to control the rendering of the game world, focusing on a specific player or entity while handling the rendering of only the visible portion.

This site is open source. Improve this page.