UE Blueprint Fundamentals | Class #5-1 | Loops & Arrays Applied #1

Summary

This tutorial demonstrates how to find the closest object to a character in Unreal Engine using Blueprint visual scripting. The presenter explains how to create a function that calculates distances between the character and a set of objects, updates the closest object based on distance, and provides real-time feedback through debug spheres. With the use of arrays, for loops, and timers, this beginner-friendly method helps users understand key programming concepts like distance calculation and variable updating. It's a useful technique for game developers looking to implement object proximity features in Unreal Engine.

Takeaways

• 😀 You will learn how to use 'for loops' and arrays to find the closest object to a character in Unreal Engine.
• 😀 The problem is broken down to finding the closest object from an array of items (A, B, C, D) by calculating the distance from the character.
• 😀 The logic involves measuring distances between the character and objects and updating the 'closest so far' variable if a closer object is found.
• 😀 The approach uses an array where each item is compared in turn to find the closest one by updating the closest distance.
• 😀 The process starts with setting an initial 'closest distance' value to a very large number to ensure the first object gets selected.
• 😀 Unreal Engine's Blueprint system is utilized for visual scripting, where a 'get closest object' function is created to perform the comparison.
• 😀 The system uses the 'Get All Actors of Class' node to get the objects to compare against and then calculates the distance between the player and each object.
• 😀 A local variable is used to track the closest distance and object so far, and the closest object is updated if a closer one is found.
• 😀 The closest object is returned at the end of the function, and a debug sphere is drawn at the location of the closest object for visualization.
• 😀 The process is further automated with a timer that checks the closest object every 2 seconds, making it update as the player moves around.

Q & A

What is the main goal of the script in this video?

The main goal is to teach how to use for loops and arrays in Unreal Engine's Blueprints to find the closest object (item, enemy, etc.) to a character. This is achieved by comparing distances between the character and objects in an array.

Why is the closest distance initialized to a very large number (like 100,000 or a million)?

The closest distance is initialized to a very large number to ensure that any item checked in the loop will be considered closer during the first iteration, as all initial distances will be smaller than this value.

How does the script determine which object is the closest to the character?

The script calculates the distance between the character and each object in the array. It then compares each distance to the current closest distance so far. If a smaller distance is found, the closest object and closest distance are updated.

What does the 'for loop' do in this Blueprint setup?

The 'for loop' iterates through each object in the array, calculates the distance between the character and each object, and checks if the calculated distance is smaller than the current closest distance so far. If true, it updates the closest distance and object.

What is the purpose of the 'get all actors of class' node in Unreal Engine?

The 'get all actors of class' node is used to gather all the instances of a specific class (in this case, 'item base') within the scene. This array of actors is then processed to find the closest one to the character.

How does the script update the closest object and its distance during each iteration of the loop?

During each iteration, the script compares the distance to the current closest object. If the new distance is smaller, it updates both the closest object reference and the closest distance so far to the new values.

What is the purpose of the custom event 'Mark Closest Item' in the Blueprint?

The 'Mark Closest Item' custom event calls the 'get closest object' function and, after determining the closest object, it draws a debug sphere at that object's location. This helps visualize which object is closest at any given moment.

What does the 'draw debug sphere' function do in this Blueprint setup?

The 'draw debug sphere' function visualizes the location of the closest object by placing a sphere (with specified radius, color, and duration) at that object's position in the game world.

Why is the 'Set Timer by Event' node used in this script?

The 'Set Timer by Event' node is used to repeatedly call the 'Mark Closest Item' event every 2 seconds. This ensures that the closest object is checked and updated periodically, without constantly relying on the tick function.

What is the 'closest object so far' variable used for in this script?

The 'closest object so far' variable holds a reference to the object that is currently considered the closest to the character, based on the distance comparisons made in the loop.