4.3.2 Button Interactions

‍Slides.pdf

Slides.pptx

Learning Objectives

Upon completing this section, students will be able to:

• use the Unity Spring Joint component to create spring-like physics interactions.
• use a combination of colliders in a single prefab to contain a specific interaction.
• use the unity event system to broadcast events that trigger interactions in other gameobjects.
• understand and use smooth interpolation to control the motion of kinematic rigidbodies.

Lesson Overview

Spring Joints

• To get the button pad to move up and down as a button normally would, we can use a Spring Joint component.
• A Spring Joint is like an invisible spring connecting one body to another.
• The Anchor is where the spring’s force is applied.
• The Spring property controls the magnitude of the spring force when it is stretched or compressed away from its resting point.
• The Damper property is like drag.

Button Movement

• We can use two Box Colliders to approximate the shape of the button pad.
• A Spring Joint is added to the button pad, and the button holder is set as the Connected Body.
• To prevent unwanted movement of the button pad, we can constrain its movement to be only vertical using the constraint properties in its Rigidbody component.

Button Functionality

• A trigger box collider on the Button prefab is placed below the button pad so that when the pad is pressed down, their colliders touch.
• The Button script detects when the button is pressed down and calls a script on other GameObjects using SendMessage.
• To prevent the code in OnTriggerEnter from executing twice, we create a bool debounce and set it to true in OnTriggerEnter and return when debounce is true.

Elevator Movement

• The wood palette is animated to move up and down like an elevator.
• In the BtnToggleAnimation script, we create an OnButtonDown method, which is called in the Button script when the player presses the button.
• OnButtonDown toggles the animation on and off by calling SetTargetSpeed, which sets the target speed to 1 or 0.
• Inside Update, the animator.speed is smoothly transitioned using linear interpolation (Mathf.Lerp).