Colliders as Triggers - Unity Official Tutorials

Summary

Highlights

• Enabling 'Is Trigger' on a collider allows objects to pass through without physical collision. ✨
• Scripts can register and log trigger events like OnTriggerEnter to track object interactions. 📜
• A trigger zone can modify an object's behavior, such as making it hover, without touching other geometry. 🕹️
• Using a rigidbody with static trigger colliders is standard practice for stability. ⚙️
• Parameters like force direction and intensity can be adjusted for different effects. 🎛️

Key Takeaways

• Check 'Is Trigger' on a collider to let objects pass through it without collision. 🛡️
• Use trigger events like OnTriggerEnter, OnTriggerStay, and OnTriggerExit to detect interactions. 🎮
• Trigger colliders are great for effects like hovering without physical contact. 🌌
• At least one object must have a rigidbody for trigger detection to work. 🤖
• You can apply forces to objects in trigger zones to create dynamic effects. 💨

Overview

Chapters

• 00:00 - 00:30: Introduction to Trigger Colliders The chapter 'Introduction to Trigger Colliders' explains how to make a collider into a trigger by checking the 'Is Trigger' checkbox in the component settings. When activated, objects will pass through the trigger collider, and this intersection can be detected via code. Unlike regular colliders, objects won't physically collide or bump into the trigger. The chapter uses an example of a box collider set as a trigger and describes a scenario with a falling 'prop samoflange' ball object interacting with it.
• 00:30 - 01:00: Using Scripts for Trigger Events The chapter discusses the process of using scripts to handle trigger events in a game environment. It explains how an object interacts with a trigger by entering, remaining, and then exiting it. Scripts are attached to the trigger to monitor these interactions using OnTriggerEnter, OnTriggerStay, and OnTriggerExit functions, with each interaction logged to the console for review. The transcript also suggests pausing the game and stepping through frame by frame to observe these events in detail via the console.
• 01:00 - 01:30: Rigidbodies and Static Objects This chapter discusses the interaction between rigidbodies and static objects, particularly in the context of trigger colliders in a physics engine. It explains the requirement that one object involved in a collision must have a rigidbody, and it is standard practice for trigger colliders to be static objects that are not moved by the engine. The chapter illustrates this concept with an example where a rigidbody object passes through a trigger.
• 01:30 - 02:00: Trigger Zones and Interactions The chapter discusses trigger zones and interactions in game development, describing how trigger colliders can be used to run code when objects enter specific areas without requiring physical collisions. The concept is illustrated using a hoverpad example, where the trigger zone is utilized to apply force to an object, creating a hovering effect as long as it remains within the zone. The chapter also touches on tracking objects that stay within a trigger zone, using variables to keep reference to such objects.
• 02:00 - 02:30: Applying Forces and Hovering Effect The chapter titled 'Applying Forces and Hovering Effect' discusses the process of applying forces to an object, specifically in the context of game development or simulation using a physics engine. It starts by addressing a collider of type Rigidbody, which is a component used to apply physics properties to objects. The chapter explains how to apply a force in the upward direction using Vector3.up—a shortcut for 'up' in world coordinates. This force is multiplied by a variable number and uses the acceleration mode in the AddForce function to influence the object. The object is then moved over a hoverpad, keeping its position frozen on the X and Z axes through the 'Freeze Position' setting. This configuration allows only the Y-axis force to affect the object, creating a hovering effect.
• 02:30 - 03:00: Conclusion and Demonstration This chapter covers the concept of a hovering effect created through an interface mechanism. A practical demonstration is conducted, showing how the effect can occur without the need for direct interaction with the geometry, simply by maintaining position within a defined area. The chapter ends with contributions noted from the Amara.org community for subtitle support.

Colliders as Triggers - Unity Official Tutorials Transcription

• 00:00 - 00:30 In order to make a collider into a trigger we simply check the 'Is Trigger' checkbox on the component settings in the inspector. When a collider is a trigger things will no longer bump into it. Instead they will pass through it and this can be detected via code. Similar to normal colliders, events are called when other colliders are overlapping with the trigger collider. In this example we have a box collider with Is Trigger checked and a falling 'prop samoflange' ball object.
• 00:30 - 01:00 This object enters the trigger, stays as it rolls forward and then exits. To check these events we attach a script to the trigger, which is registering OnTriggerEnter and logging to the console and likewise OnTriggerStay and OnTriggerExit. So if we pause the game and step through one frame at a time, looking at the console will show that the object enters the trigger
• 01:00 - 01:30 stays for a number of frames and eventually exits the trigger. In the same way as standard collisions, one of the two objects must have a rigidbody. It's standard practice to make sure that your trigger colliders are static objects, meaning they will not be moved by the physics engine. So usually you will make a trigger and then pass a rigidbody through it. This example is no different. We're passing our rigidbody object
• 01:30 - 02:00 through the trigger zone and detecting when something enters that trigger. So the intention with the trigger collider, also known as a trigger zone, is that you can call code without the objects in your game physically colliding. So for example, with our hoverpad, we can add a force to our samoflange ball to give the effect of it hovering so long as it stays within the trigger zone. For example, we could address the object that's currently staying within the trigger because the object that's staying is saved in a variable called 'other'
• 02:00 - 02:30 of type Collider. We could then address the rigidbody and add a force in the direction of Vector3.up, a shortcut for 'up' in world coordinates. We could then multiply by a number which we'll save as a variable. And we'll finish out the AddForce by choosing acceleration as the mode. Now we'll move our object over the hoverpad and we'll use Freeze Position to keep it in the same place in X and Z. Allowing the force of Y to create
• 02:30 - 03:00 the hovering effect. And now if I press play, as you can see as long as it stays within that area it creates the effect of hovering without having to interact without any part of the geometry. Subtitles by the Amara.org community