13 - Building a Browser-Embedded Game — Topics & Learning Outcomes

Module Topics

Game Design Fundamentals

• Defining the Game Objective — Every game needs a clear, singular goal that tells the player what they are trying to achieve.
• Establishing the Rules — Rules define the boundaries of player behavior and determine how the game world responds to actions.
• Identifying Game Entities — Game entities are the objects and characters that exist within the game world and interact with each other.
• Sketching the Game Structure — Before writing any code, outlining the overall structure of the game — its states and flow — provides a roadmap for development.
• Scoping the Project Appropriately — Choosing a game concept that matches the available time and technical skills is a critical design decision.
• Planning the Player Interaction Model — The interaction model describes how the player controls the game, which directly shapes the event handling code you will write.

Canvas Drawing for Games

• Setting Up the Canvas Element — The HTML5 Canvas element provides a drawable surface within the browser that games use as their visual output.
• Drawing Background Layers — A game background provides the visual environment and is typically drawn first so all other elements appear on top of it.
• Rendering Character Sprites — Characters are the player-controlled or animated figures drawn onto the canvas to represent the main actors in the game.
• Drawing Obstacles and Game Objects — Obstacles and collectibles are additional drawn elements that create challenge and interactivity within the game world.
• Clearing and Redrawing the Canvas — Because games update visually many times per second, the canvas must be cleared before each frame is redrawn to prevent visual artifacts.
• Using Coordinates and the Canvas Grid — The canvas uses a pixel-based coordinate system where (0, 0) is the top-left corner, with x increasing to the right and y increasing downward.

Animation and the Game Loop

• What Is a Game Loop? — A game loop is a continuous cycle that updates game state and redraws the screen many times per second to create the illusion of motion and interactivity.
• Introducing requestAnimationFrame — requestAnimationFrame is a browser API that schedules a callback function to run just before the browser paints the next frame, typically 60 times per second.
• Writing the Core Loop Function — The loop function is called on every frame and serves as the heartbeat of the entire game, coordinating all updates and drawing in the correct order.
• Updating Game State Each Frame — The update step advances all game objects — such as player position, enemy movement, and score — based on logic and elapsed time before anything is drawn.
• Delta Time and Frame-Rate Independence — Delta time is the number of milliseconds elapsed since the last frame, and multiplying movement values by it ensures objects move at a consistent speed on any device.
• Starting and Stopping the Loop — The loop must be explicitly started once when the game begins, and it can be stopped by cancelling the scheduled animation frame when the game ends or pauses.

Event Handling and Player Input

• Attaching Event Listeners to the Document or Canvas — Event listeners are registered using addEventListener() on the document or the canvas element to begin capturing player input.
• Reading Keyboard Input — Keyboard events expose properties like event.key and event.code that identify which key was pressed, released, or held down.
• Reading Mouse Input — Mouse events provide cursor coordinates and button state, allowing players to aim, click, or drag within the game canvas.
• Handling Touch Input for Mobile Play — Touch events mirror mouse events but support multiple simultaneous contact points, making them essential for mobile-compatible games.
• Translating Raw Input into Game Actions — Raw event data must be mapped to meaningful in-game behaviors such as moving a character, firing a projectile, or pausing the game.
• Preventing Default Browser Behavior — Many keys and gestures trigger built-in browser behaviors that can disrupt gameplay and must be suppressed with event.preventDefault().

Game Logic and State Management

• Tracking Game State — Game state refers to all the variables that describe the current condition of the game at any moment, such as whether the game is running, paused, or over.
• Implementing a Scoring System — A scoring system rewards players for successful actions and provides feedback on their performance throughout the game.
• Collision Detection — Collision detection determines when two game objects occupy the same space, triggering gameplay consequences such as losing a life or earning a point.
• Win Conditions — A win condition is a specific goal the player must achieve to successfully complete the game or a level.
• Loss Conditions and Lives — Loss conditions end the game when the player fails to meet survival requirements, such as running out of lives or time.
• Resetting and Restarting the Game — Providing a reset mechanism lets players try again without reloading the page, improving the overall user experience.

Integrating and Assembling the Complete Game

• Establishing the Project Structure — A well-organized file and code structure is the foundation of a complete, maintainable browser game.
• Combining Drawing and Animation Systems — The visual layer of the game requires merging Canvas drawing routines with the animation loop established in earlier lessons.
• Wiring Up Event Handling and Player Input — Player interaction is connected to the game by attaching the event listeners built in previous lessons to the unified game loop.
• Implementing the Unified Game Loop — The game loop is the central engine that calls update and render in sequence every frame, tying all subsystems together.
• Integrating Game Logic and Win/Lose Conditions — All collision detection, scoring, and state-transition logic developed earlier must be consolidated into the update phase of the game loop.
• Testing and Debugging the Complete Project — Once all components are assembled, systematic testing ensures the integrated game behaves correctly as a whole.
• Embedding and Presenting the Finished Game — The final step is ensuring the completed game runs reliably in a browser and is ready to be shared or submitted as a finished project.

Student Learning Outcomes

By the end of this module, students will be able to:

Course Outcomes (reference)

No course outcomes have been defined.