Cycle 4.5: Basic Interaction System MVP Guide

Embarking on game development requires a structured approach, and Cycle 4.5 focuses on implementing a Minimum Viable Product (MVP) for a basic interaction system. This article serves as a comprehensive guide, detailing the objectives, tasks, and technical specifications involved in creating a foundational interaction system for your game. Let's dive in and explore the intricacies of building an interactive world!

📊 Overview

Before we delve into the specifics, let's outline the core objectives and criteria for success.

Objective: To establish a basic interaction system enabling players to interact with objects like doors and chests within the game environment.

Success Criteria: The system should facilitate interaction with doors (opening and closing) and chests (opening and item collection), accompanied by clear visual feedback to the player.

Estimated Time: The development is projected to take approximately 5-7 hours, encompassing all micro-tasks.

Work in Progress (WIP): The focus will be maintained on a maximum of 1-2 tasks concurrently to ensure efficiency and quality.

Dependencies: This cycle relies on the successful completion of:

• Cycle 1.7 (MVP of the Input System)
• Cycle 4.2 (MVP of the Controllable Character)

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🎯 MVP: Functional Basic Interaction System

The primary goal of this cycle is to develop a functional MVP for the interaction system. This involves breaking down the development process into manageable micro-tasks, each contributing to the overall objective.

Micro-Tasks

• 4.5.1 Creating the IInteractable Interface (1 hour)

  • The foundation of any interaction system lies in defining what it means for an object to be interactable. This task involves creating an IInteractable interface that will serve as a contract for all interactive objects within the game. The first step is to define the IInteractable interface, which will act as a blueprint for all interactive objects in the game. This interface specifies the basic functionality required for an object to be considered interactable, ensuring a standardized approach across different types of objects, such as doors, chests, and more. This includes declaring a function named Interact(), which will be the core method called when the player attempts to interact with an object. This function serves as the entry point for interaction logic, defining what happens when a player engages with an object. Once the interface and the Interact() function are defined, the next crucial step is to verify the integrity of the interface. This involves ensuring that the interface is correctly structured and that the Interact() function is properly defined according to the project's coding standards and requirements. Proper verification at this stage prevents potential issues and ensures that all interactive objects can seamlessly implement the interface. The creation and verification of the IInteractable interface are critical for setting a solid foundation for the game’s interaction system. By establishing a clear contract for interactive objects, the game ensures consistency and extensibility, allowing for the addition of new interactive elements in the future without disrupting existing functionality. This systematic approach to design not only simplifies the development process but also enhances the overall maintainability and scalability of the game.

• 4.5.2 Implementing Door Interaction (Open/Close) (2 hours)

  • Doors are a fundamental element in most games, providing barriers, transitions, and thematic elements. This task focuses on implementing the interaction logic for doors, allowing players to open and close them. The initial step in this process is to create a Door class that implements the IInteractable interface. This class will encapsulate all the necessary logic and properties specific to doors, such as their current state (open or closed) and any visual or auditory feedback associated with their interaction. By implementing the IInteractable interface, the Door class ensures that it adheres to the standardized interaction contract defined earlier, allowing it to seamlessly integrate into the game’s interaction system. Following the creation of the Door class, the next crucial step is to implement the open/close logic. This involves defining the behavior of the door when the Interact() function is called. For instance, if the door is closed, the Interact() function should trigger the door to open, and vice versa. This logic may include setting flags to indicate the door's state, managing collision properties, and triggering animations or sound effects to provide feedback to the player. To enhance the player’s experience and provide clear feedback, adding a basic animation for the door’s opening and closing is essential. This animation might involve the door swinging open or sliding to the side, depending on the design. Implementing a visual cue that corresponds to the interaction not only makes the game more immersive but also confirms to the player that their action has been registered and executed correctly. After implementing the door interaction logic and animation, thorough testing of the interaction is necessary to ensure it functions as expected. This testing should cover various scenarios, such as interacting with the door from different angles, rapidly opening and closing the door, and ensuring that the door’s state is correctly maintained. Addressing any issues or bugs at this stage ensures a smooth and reliable gameplay experience, allowing the player to navigate the game world seamlessly.

• 4.5.3 Implementing Chest Interaction (Open/Collect Item) (2 hours)

  • Chests often hold valuable items and secrets, making their interaction a key part of the player's experience. This task involves implementing the interaction logic for chests, allowing players to open them and collect items. The process begins with creating a Chest class that implements the IInteractable interface. Similar to the Door class, this class will encapsulate all the properties and behaviors specific to chests, such as their current state (open or closed), the items they contain, and any visual or auditory effects associated with their interaction. Implementing the IInteractable interface ensures that the Chest class integrates seamlessly into the game’s broader interaction system, adhering to the established contract for interactive objects. The next step is to implement the logic for opening the chest. This involves defining what happens when the Interact() function is called on a chest. Typically, this will include changing the chest’s state from closed to open, triggering an animation of the chest lid opening, and potentially playing a sound effect to enhance the feedback. The opening logic may also need to manage visual elements such as particles or light effects to draw the player’s attention to the contents of the chest. In addition to opening the chest, the system must implement the functionality for collecting items from the chest. This involves managing the items contained within the chest and transferring them to the player’s inventory. The logic should ensure that items are correctly added to the inventory, taking into account any limitations on inventory space or item types. It may also include visual feedback, such as displaying the collected items to the player or playing an animation to indicate the item transfer. After implementing the chest interaction logic and item collection functionality, comprehensive testing of the interaction is essential. This includes verifying that the chest opens correctly, items are transferred to the player’s inventory without issues, and any visual or auditory feedback is properly triggered. Thorough testing helps to identify and resolve any bugs or inconsistencies, ensuring a seamless and rewarding experience for the player when interacting with chests in the game.

• 4.5.4 Adding Visual Feedback (Highlight) (1 hour)

  • Visual feedback is crucial for guiding players and making interactions intuitive. This task focuses on adding visual cues, such as highlights, to indicate interactive objects. The primary goal is to implement a highlight effect that activates when the player is in close proximity to an interactable object. This highlight serves as a visual cue, signaling to the player that the object can be interacted with. The effect can be achieved through various methods, such as changing the object’s outline, adding a glow, or altering its color. The implementation should ensure that the highlight is visually distinct and noticeable, but not overly intrusive, maintaining a balance between guidance and aesthetics. In addition to the highlight effect, adding a visual indicator further enhances the player’s understanding of the interaction. This indicator might be an icon, such as a hand or a button prompt, that appears above the object or near the player character. The visual prompt should clearly communicate the action that can be performed, such as “Open” for a door or “Search” for a chest. The combination of the highlight and the indicator provides a comprehensive visual guide, making the interaction process more intuitive and user-friendly. After implementing the highlight effect and the visual indicator, thorough testing of the feedback is essential. This involves ensuring that the highlight and indicator appear correctly when the player is within interaction range, that they disappear when the player moves out of range, and that they do not interfere with other visual elements in the game. Testing should also verify that the feedback is consistent across different types of interactable objects and in various lighting conditions. Ensuring that the visual feedback is clear, consistent, and responsive greatly improves the player’s experience, making the game more engaging and enjoyable.

• 4.5.5 Testing Interactions (1 hour)

  • Rigorous testing is essential to ensure the interaction system functions smoothly and reliably. This task involves thoroughly testing all implemented interactions to identify and resolve any issues. The first step in this testing phase is to test the door interaction. This includes verifying that the door opens and closes correctly when the player interacts with it, that the animation plays smoothly, and that any associated sound effects are triggered as expected. Testing should cover various scenarios, such as interacting with the door from different angles and rapidly opening and closing it, to ensure the interaction is robust and consistent. Next, testing the chest interaction is crucial to ensure that it functions properly. This involves verifying that the chest opens when interacted with, that the item collection process works correctly, and that the items are transferred to the player’s inventory without issues. Testing should also confirm that the chest’s state (open or closed) is accurately maintained and that any visual or auditory feedback is properly displayed. Testing the visual feedback is another critical aspect of this phase. This includes ensuring that the highlight effect and the interaction prompt appear correctly when the player is within range of an interactable object and that they disappear when the player moves out of range. The testing should verify that the visual cues are clear and consistent across different types of objects and in various environmental conditions. Finally, the testing process should verify that all components of the interaction system work together seamlessly. This involves playing through the game, interacting with different objects, and ensuring that there are no conflicts or unexpected behaviors. Comprehensive testing helps to identify and resolve any issues, ensuring that the interaction system is polished and reliable, and that it enhances the player’s experience rather than detracting from it.

✅ Definition of Done

To ensure the cycle is complete and successful, we need to adhere to a clear definition of done.

The Cycle is not "Done" until:

• [ ] Code is implemented and tested thoroughly
• [ ] The interaction system functions as expected
• [ ] Documentation (GDD/TDD) is updated as necessary
• [ ] CHANGELOG.md is updated if significant changes are made

Corresponding Documentation

This cycle updates:

• GDD: Physics and Interaction - Interaction System
• TDD: Interaction - Technical Interaction System
• GDD: UI/UX - Feedback - Visual Feedback

Action: Update the documents above upon completion of this cycle.

📝 Object-Action-Reaction Model (Aligned with Compendium)

Understanding the technical specifications is crucial for implementing the interaction system effectively.

Door Interaction - Technical Description:

• Object: Door (DoorActor) with Open/Closed state
• Initial State: Door closed, highlight disabled
• Player Action: Pressing the 'E' key within interaction range (2m)
• System Reaction:
  1. Check if player is in range: IF Distance < 2.0m THEN
  2. Activate highlight: Door.SetHighlight(true)
  3. Show prompt: `ShowPrompt(