WEBVTT

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Realistic Immersion Advanced Edition
VR project implementation 1

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We'll now try to implement

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grabbing and lifting objects

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placed in the world space

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by hand

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Additionally, we will practice both lifting objects

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while maintaining the grabbed position and using a snap feature

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where objects attach to a specific position

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on the hand when grabbed

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We will also spend time implementing a feature

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that applies animations of the hand opening and closing

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based on the VR controller's input state

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making the act of grabbing and releasing objects appear more natural

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Applying Hand Animation

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Let's continue from where we left off last time

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When we grab or throw an object

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we usually grasp it

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as if we were clenching our hand to give it a more realistic feel

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To create the effect of grasping

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we will add a simple animation to the hand

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And let's start by focusing on the right hand for now

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Let's start by creating the input keys first

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Right-click on Inputs and

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add an Input Action to Input

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and name it IA_HandTrigger_Right

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Since we only need the Right Hand Trigger to detect

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when it's pressed and released when grabbing

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let's set it to digital input mode

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We'll receive values as True or False for this input

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Add another mapping

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in the Input Mapping Context

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and select IA_HandTrigger_Right

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Let's select the Right Grip button

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on the Oculus Touch for the key

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This will now correspond to True or False values

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Let's save it for now

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Let's go ahead and add a few more keys while we're at it

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To express animations

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we need to remember how our index, middle, and other fingers moved, right?

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So, let's add an Input Action to Input

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and name it IA_IndexTrigger_Right

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For the Index Trigger, we'll set the Value Type

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to Axis1D (float)

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so it can detect how much it's pressed

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allowing animations to correspond to the degree of pressure applied

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If we're going to receive it as a float anyway, let's change the name accordingly

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Let's distinguish between True/False

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and Float here by adding "Float" to the name

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So it will be named IndexTriggerFloat_Right

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 Let's proceed to add an Input Action

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named IA_HandTriggerFloat_Right in Input

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I'll add three things

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Index Trigger Float for the right hand

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 Hand Trigger Float for the right hand

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and True/False Boolean values

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Since Hand Trigger Float will also be received as a float

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let's set it to Axis1D (float)

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for one-dimensional coordinates

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Then, since it's a Skeletal Mesh

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for the right hand's Skeletal Mesh

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there's an Anim Class where we can set up animations

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Considering the time, we won't create a new one from scratch

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We'll try using animations

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that were already present in the VR template

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The animations should be located under Characters here

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In the Characters folder, inside MannequinsXR

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there's a folder named Animations

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So, here you'll find animations related to the hand movements

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These animation files are used to blueprint

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within the Meshes folder

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where you can find

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the MannequinsXR animation file

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We'll use these to apply animations to our hands

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So, we'll duplicate this by using Ctrl + D

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Let's name this ABP_HunetHand then

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I duplicated it with the name HunetHand

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I created a new folder named Animations in Content

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and placed the HunetHand file inside

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I'll move the duplicated HunetHand file

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to the Animations folder here

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I'll place the ABP_HunetHand animation blueprint file

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we just created

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 using this file into

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the Animations folder

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If you double-click to open the animation blueprint file

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you'll see that it's already partially implemented

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If you look at the values, in the preview section here

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you'll see things like Pose Alpha Grasp, followed by Index Curl Point

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Thumb Up, and so on

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So just by looking at the name

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Index Curl refers to when the index finger curls upwards

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Alpha Grasp would refer to when making a fist

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and Thumb Up would correspond to

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when the thumb is raised

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Go ahead and try changing some values here

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If you increase the Pose Alpha Grasp value

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what would happen?

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The Pose Alpha Grasp value typically ranges from 0 to 1

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influencing the positions of multiple fingers

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like index, middle, and ring fingers

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We can use the float value

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from our right hand's HandTrigger to control this Pose Alpha Grasp value

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allowing us to represent a range from 0 to 1

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Below that, there's Pose Alpha Index Curl

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Pose Alpha Index Curl also allows you to bend and straighten the index finger

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using a value ranging from 0 to 1

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So, to effectively use finger animations

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we'll use Pose Alpha Grasp and Pose Alpha Index Curl values to apply animations

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Let's give it a try

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The rest, you can experiment with by adjusting them

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based on when, how, and which inputs you want to use

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to control the values

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Let's focus on showing these two first

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Then let's head over to the Hunet Player

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where in BeginPlay

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we'll store the initial animation blueprint values

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So, we'll get the animation instance

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from the right hand's Anim Instance

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to directly pass values

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 to the animation blueprint

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We'll cast the result of Get Anim Instance

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We'll cast it to the ABP_HunetHand

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that we created

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So, we'll store this casted ABP_HunetHand

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as a variable

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Let's name this variable

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RightHandAnim

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We'll name the variable RightHandAnim without spaces

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It's generally better to avoid spaces in variable names

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so we'll name it accordingly

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Now that we've stored the variables

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we just need to pass values

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to each of them

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So, let's add an event below for this

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We'll receive the IA_HandTriggerFloat_Right event

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and continuously pass its values to RightHandAnim

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while the event is pressed

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So, we'll use Get RightHandAnim to retrieve RightHandAnim

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to retrieve RightHandAnim

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and then continuously pass this value

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to Set Pose Alpha Grasp

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We'll pass the Action Value

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to Set Pose Alpha Grasp like this

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Similarly, let's duplicate it with Ctrl + D

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then ensure to also pass the Action Value to Set Pose Alpha Grasp

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when releasing the hand at the end

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To ensure it perfectly resets to 0

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we should also target the RightHandAnim variable in this duplicated event

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We'll do the same for the index finger as well

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For IA_IndexTriggerFloat_Right

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we'll also retrieve RightHandAnim

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and use Set Pose Alpha Index Curl

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 to pass the Action Value like this

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Of course, we'll duplicate it with Ctrl + D

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connect it to the same target for when the action is completed

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and pass the Action Value of 0

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to ensure the hand fully extends

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Let's compile and save the changes

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Next, we need to link this event to the Input Mapping Context

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as we've only created the event so far

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We'll add two mappings

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to the Input Mapping Context

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The first one will be IA_HandTriggerFloat_Right

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and we'll map it to the Right Grip Axis

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on the Oculus Touch

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Then, we'll add one more

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and collapse any unnecessary sections for clarity

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We'll add IA_IndexTriggerFloat_Right next

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and we'll assign it to the Trigger Axis

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on the Oculus Touch Right controller

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Next, let's save the mappings

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Let's test to see if everything is working correctly now

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When you grab the right hand controller

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and squeeze the Hand Trigger or the index trigger

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you should see animations

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that simulate gripping or making a fist

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Now that we've simulated the gripping animation

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let's create an object here

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so that when we actually grasp it

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the object will appear to be held in our hand

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Let's place a table on the ground

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so it's easier to pick up objects

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then we'll place an object on top of it

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Since we have StarterContent available

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let's find a table from the Props section

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 in StarterContent

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and place it here

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If the table feels too small, feel free to scale it up

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Let's place it nearby

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so we can grab it easily

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 since we haven't implemented movement functionality yet

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If you feel it's a bit small

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locking the scale to about 1.2 times its current size

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will adjust all dimensions simultaneously

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Setting it to 1,2 will increase its size uniformly, making it slightly larger

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Let's place an object on top of it

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We'll create a blueprint for this object separately

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First, let's create a new Blueprint Class

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in Blueprints

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Let's create it as an Actor type

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Next, I'll create a blueprint file

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named BP_GrabObject

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Open up the file by double-clicking

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Here, let me search for 'Box'

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When you search for Box

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there's something called Box Collision

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So, you'll move this Box Collision to be the root

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making it the Root Component

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Next, I'll add a Static Mesh below it

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And in the Static Mesh details panel

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you can choose any object

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 that could serve as

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the shape of the object

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Shall we place something angular? If we place something too round

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 it might not fit well with the Box Collision

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Let's place a statue

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Since the color may not be very visible

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 let's compile it first

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When you compile, the materials will appear, right?

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Currently, it might be a glass material, so it may not be very visible

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Shall we change it to a more opaque color

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to make it more visible?

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That should make it more noticeable, right?

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After changing the color

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let's adjust it to fit

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somewhat within the box size like this

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And compile, save. Since we need to handle collision later

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for the Box - Static Mesh of this object

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let's change the Collision Preset to No Collision

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so that the Static Mesh itself doesn't have collision

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We'll set it up so that only the box has collision applied

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So, let's customize

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the collision settings in the box

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Let's customize it

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so we can cut it as we please

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For the Object Type, let's set it to World Dynamic

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Next, let's change Collision Enabled

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 to Query and Physics

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Let's set everything to block

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so that it blocks everything like this

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If you check the "Block" above

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it will change everything uniformly to "Block"

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So, we'll set it to "Block" for all channels

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ensuring that

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physically nothing can pass through

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Next, for this object

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we'll enable "Simulate Physics"

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 so that it can fall under gravity

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and not float in the air

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Turn on "Simulate Physics" for it

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Then compile and save it

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And now let's go back to the map

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and place the Grab Object

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on top of the table

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The size seems quite large. Should we resize it smaller?

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Reducing it to about half its size should be fine

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Reducing it to 0.5 times its current size will still make it quite large

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so let's press the End key on the keyboard

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to snap it neatly to the floor

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Just to be safe

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let's place one more next to it like this

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You know you can hold down the Alt key and drag to duplicate, right?

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So, I'll place these two

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on the table like this

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And for the Table Actor

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since its collision settings are probably default

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00:19:30.977 --> 00:19:34.427
I'll customize it to set the Object Type

268
00:19:34.427 --> 00:19:37.127
to World Static

269
00:19:37.127 --> 00:19:39.977
and leave it as it is

270
00:19:39.977 --> 00:19:43.227
For the moving objects here

271
00:19:43.227 --> 00:19:45.977
set them to World Dynamic

272
00:19:45.977 --> 00:19:48.627
and for the fixed table, set it to World Static

273
00:19:48.627 --> 00:19:53.327
So, to determine when

274
00:19:53.327 --> 00:19:56.327
the player has grabbed an object

275
00:19:56.327 --> 00:19:59.677
we'll add an event here

276
00:19:59.677 --> 00:20:06.577
IA_HandTrigger will be for functionality, not animation

277
00:20:06.577 --> 00:20:08.427
so we'll use True and False values

278
00:20:08.427 --> 00:20:12.177
So, we'll create an Enhanced Input Action for IA_HandTrigger_Right

279
00:20:12.177 --> 00:20:15.977
using True and False values

280
00:20:15.977 --> 00:20:20.227
Next, we'll check

281
00:20:20.227 --> 00:20:22.327
when the button is pressed

282
00:20:22.327 --> 00:20:25.477
We'll check when the button is pressed (Started)

283
00:20:25.477 --> 00:20:28.227
to see what objects are around our hand

284
00:20:28.227 --> 00:20:31.677
at that moment

285
00:20:31.677 --> 00:20:36.377
In this case, we'll use an Overlap check

286
00:20:38.827 --> 00:20:44.327
Since we're checking around the hand, we can use a Sphere Overlap

287
00:20:44.327 --> 00:20:50.577
We'll search

288
00:20:50.577 --> 00:20:51.977
for Sphere Overlap Actors

289
00:20:51.977 --> 00:20:56.277
This function searches

290
00:20:56.277 --> 00:20:58.777
within a specified radius, measured in centimeters

291
00:20:58.777 --> 00:21:04.427
from the position you define, within a single frame

292
00:21:04.427 --> 00:21:07.027
So, what will the reference point be?

293
00:21:07.027 --> 00:21:12.027
The reference point will be the position of the right hand

294
00:21:12.027 --> 00:21:14.277
 You can use either the Right Motion Controller

295
00:21:14.277 --> 00:21:17.127
or the Right Hand for this

296
00:21:17.127 --> 00:21:18.977
Most likely, they should be nearly identical in position

297
00:21:18.977 --> 00:21:22.227
because the location value for the hand is

298
00:21:22.227 --> 00:21:24.127
relative with coordinates set to 0, 0, 0

299
00:21:24.127 --> 00:21:26.577
it aligns with the parent's position

300
00:21:26.577 --> 00:21:30.127
We'll use the Right Motion Controller as the reference point for the parent

301
00:21:30.127 --> 00:21:34.627
We're going to use

302
00:21:34.627 --> 00:21:38.327
Get World Location

303
00:21:38.327 --> 00:21:40.177
for the Right Motion Controller

304
00:21:40.177 --> 00:21:42.477
to get its location in the world

305
00:21:42.477 --> 00:21:48.527
So, w're going to use the World Location

306
00:21:48.527 --> 00:21:55.227
to search around the hand

307
00:21:55.227 --> 00:21:58.727
with a radius of about 15cm

308
00:21:58.727 --> 00:22:02.959
15cm is quite a reasonable radius for detecting objects around the hand

309
00:22:02.959 --> 00:22:06.809
Given the slight differences between VR and the real world

310
00:22:06.809 --> 00:22:09.609
a bit of extra radius like 15cm should indeed help ensure

311
00:22:09.609 --> 00:22:12.777
comfortable interaction without feeling too restrictive

312
00:22:12.777 --> 00:22:16.677
I'll search around the hand

313
00:22:16.677 --> 00:22:20.127
within a radius of about 15cm

314
00:22:20.127 --> 00:22:22.127
Then we need to specify

315
00:22:22.127 --> 00:22:25.277
which actors to search for by checking the Object Type

316
00:22:26.277 --> 00:22:31.327
So, since it's in array format

317
00:22:31.327 --> 00:22:33.777
let's use 'Make Array' to create an array

318
00:22:33.777 --> 00:22:37.528
If you connect the array values to Object Type

319
00:22:37.528 --> 00:22:40.328
you'll be able to choose the Object Type

320
00:22:40.328 --> 00:22:42.978
Here, for the object like the Statue we intended to grab earlier

321
00:22:42.978 --> 00:22:47.728
it was set to World Dynamic

322
00:22:47.728 --> 00:22:50.778
So we'll check only for the World Dynamic type here

323
00:22:50.778 --> 00:22:54.328
Next, for Ignore Actors

324
00:22:54.328 --> 00:22:55.928
actors to ignore in collision checks

325
00:22:55.928 --> 00:22:59.128
we shouldn't check against ourselves

326
00:22:59.128 --> 00:23:06.478
So similarly, we will create an Array

327
00:23:06.478 --> 00:23:11.578
 and pass the Array values here

328
00:23:11.578 --> 00:23:14.278
The actor that shouldn't collide is itself

329
00:23:14.278 --> 00:23:18.978
So, we'll get a reference to self

330
00:23:18.978 --> 00:23:23.229
put information about itself into the array

331
00:23:23.229 --> 00:23:26.028
to not collide itself

332
00:23:26.028 --> 00:23:29.328
I will register it as an Ignore Actor

333
00:23:34.978 --> 00:23:38.278
The Dynamic actors might not be limited to

334
00:23:38.278 --> 00:23:40.778
just the Grab Object we just created

335
00:23:40.778 --> 00:23:45.378
So just in case, we'll use a class filter

336
00:23:45.378 --> 00:23:49.678
to ensure only BP_GrabObject is checked

337
00:23:49.678 --> 00:23:52.178
Even if they are dynamic

338
00:23:52.178 --> 00:23:57.028
we'll only check those that are of the BP_GrabObject type

339
00:23:59.378 --> 00:24:03.478
Then, anyway, the result will be multiple arrays

340
00:24:03.478 --> 00:24:06.328
We will take the first one among them

341
00:24:06.328 --> 00:24:10.128
So, we'll use Get to fetch the 0th element

342
00:24:10.128 --> 00:24:13.678
which is the first one that was touched in the array

343
00:24:14.978 --> 00:24:19.678
For the retrieved entity, physics are currently enabled, right?

344
00:24:19.678 --> 00:24:21.528
So, gravity is applied

345
00:24:21.528 --> 00:24:24.078
and when we grab manually

346
00:24:24.078 --> 00:24:26.978
the object falls down due to gravity, making it hard to hold onto

347
00:24:26.978 --> 00:24:30.028
We'll need to disable physics first

348
00:24:30.028 --> 00:24:31.678
so casting should be done beforehand

349
00:24:31.678 --> 00:24:38.128
First, cast to BP_GrabObject

350
00:24:41.778 --> 00:24:49.178
We'll set the Simulate Physics of the Box Component

351
00:24:49.178 --> 00:25:01.378
from the object to false

352
00:25:01.378 --> 00:25:04.028
turning it off

353
00:25:04.028 --> 00:25:05.778
If it's checked it means it's turned on (True)

354
00:25:05.778 --> 00:25:08.578
and if it's unchecked, it means it's turned off (False)

355
00:25:09.378 --> 00:25:12.078
We'll turn off physics first

356
00:25:12.078 --> 00:25:14.328
then attach it to my hand's position

357
00:25:14.328 --> 00:25:16.928
We'll attach it to the Right Hand

358
00:25:16.928 --> 00:25:27.328
So, we'll use Attach To Component for this object

359
00:25:27.328 --> 00:25:29.828
and our hand is the Component

360
00:25:29.828 --> 00:25:33.628
Since it's a Skeletal Mesh Component

361
00:25:33.628 --> 00:25:35.878
we'll attach it to the Component

362
00:25:37.228 --> 00:25:40.878
To organize it neatly

363
00:25:43.028 --> 00:25:49.928
I'll create a reroute node and double-click to make the connection look tidy like this

364
00:26:00.528 --> 00:26:05.128
When attaching, there's a rule involved

365
00:26:05.128 --> 00:26:09.928
This rule includes three options: Keep Relative

366
00:26:09.928 --> 00:26:13.878
Keep World, and Snap to Target

367
00:26:14.228 --> 00:26:17.928
The "Snap to Target" option means that when grabbed

368
00:26:17.928 --> 00:26:20.178
 it moves to exactly match the position of my hand

369
00:26:20.178 --> 00:26:23.528
aligning precisely with it

370
00:26:23.528 --> 00:26:27.128
"Keep World" or "Keep Relative" means that when grabbed, it maintains its position relative to the world

371
00:26:27.128 --> 00:26:30.078
or relative to its parent

372
00:26:30.078 --> 00:26:32.478
while being attached

373
00:26:32.478 --> 00:26:35.328
at the moment it's grabbed

374
00:26:35.328 --> 00:26:38.378
Since it's a bit tricky to explain verbally

375
00:26:38.378 --> 00:26:40.978
I'll set all of these to

376
00:26:40.978 --> 00:26:44.378
"Keep World" for now

377
00:26:46.128 --> 00:26:49.728
Next, we'll attach it

378
00:26:49.728 --> 00:26:51.078
to my hand

379
00:26:51.078 --> 00:26:55.728
So, we'll fetch the Right Hand

380
00:26:55.728 --> 00:27:01.628
and set it as the Parent for the attachment

381
00:27:01.628 --> 00:27:06.078
So, I'll compile and save to attach it to the hand

382
00:27:07.278 --> 00:27:21.578
Then let's play again to see how it works

383
00:27:21.578 --> 00:27:24.728
It seems to be located below

384
00:27:24.728 --> 00:27:27.878
Anyway, what happens when you grab it like this?

385
00:27:27.878 --> 00:27:29.178
When you grab it now

386
00:27:29.178 --> 00:27:32.028
 it should attach precisely to your hand

387
00:27:32.028 --> 00:27:33.528
at the position where you grabbed it

388
00:27:33.528 --> 00:27:37.228
You've confirmed that when you grab it, it attaches to your hand like this

389
00:27:37.228 --> 00:27:41.028
although you haven't made the release action yet

390
00:27:41.028 --> 00:27:45.028
Implementing object grabbing functionality

391
00:27:45.028 --> 00:27:48.628
But what happens to us when it attaches like this?

392
00:27:48.628 --> 00:27:51.228
It might feel a bit awkward, right?

393
00:27:51.228 --> 00:27:55.328
If we want to specify a precise grab point

394
00:27:55.328 --> 00:27:57.678
 and have it attach exactly there

395
00:27:57.678 --> 00:28:00.378
we should change the Location Rule

396
00:28:01.778 --> 00:28:06.328
from Keep

397
00:28:06.328 --> 00:28:10.428
to Snap to Target

398
00:28:10.428 --> 00:28:13.278
instead of Keep World

399
00:28:13.278 --> 00:28:16.178
Rotation should also be set to Snap to Target

400
00:28:16.178 --> 00:28:20.178
There's no need to change Scale

401
00:28:20.178 --> 00:28:23.128
There's no need to adjust it to fit the size of the hand, just the statue

402
00:28:23.128 --> 00:28:25.228
Let's ignore scaling

403
00:28:25.228 --> 00:28:29.228
and just align the position and rotation according to the hand's direction

404
00:28:29.228 --> 00:28:33.328
I'll go ahead and compile and save these changes

405
00:28:35.528 --> 00:28:37.628
Let's test it again to see how it behaves now

406
00:28:42.578 --> 00:28:46.978
I've grabbed it
Now, when I grab it

407
00:28:46.978 --> 00:28:51.028
does it attach exactly to the position of my hand like this?

408
00:28:51.028 --> 00:28:54.478
But it seems like the position isn't quite what we wanted

409
00:28:54.478 --> 00:28:57.028
So, now we can use a Socket

410
00:28:57.028 --> 00:29:03.178
as the Grab Point

411
00:29:04.428 --> 00:29:08.278
If you look at the viewport, I'll show you the Right Hand

412
00:29:08.278 --> 00:29:12.430
If you look at the Right Hand

413
00:29:12.430 --> 00:29:15.478
you'll see that currently the pivot is around the wrist area

414
00:29:15.478 --> 00:29:19.478
So, when the statue snapped to attach

415
00:29:19.478 --> 00:29:21.828
it ended up attaching at this wrist position where the pivot is currently located

416
00:29:21.828 --> 00:29:24.028
So, earlier it looked a bit odd because of that

417
00:29:24.028 --> 00:29:28.778
So, you would typically want it to attach

418
00:29:28.778 --> 00:29:30.228
around the palm area instead

419
00:29:30.228 --> 00:29:35.078
To align it around the palm area

420
00:29:35.078 --> 00:29:38.128
you can specify the attachment point on the palm using something called a Socket

421
00:29:38.128 --> 00:29:43.478
To go to the location

422
00:29:43.478 --> 00:29:45.478
where the original file SKM_MannyXR_right for Right Hand is located

423
00:29:45.478 --> 00:29:49.778
If you click on the folder icon below

424
00:29:49.778 --> 00:29:52.478
you'll see the original location where it's located

425
00:29:52.478 --> 00:29:54.719
It's located in the Characters - Meshes folder

426
00:29:54.719 --> 00:29:59.328
Please double-click to open this file

427
00:30:03.328 --> 00:30:05.778
Please click on the skeletal icon at the top

428
00:30:05.778 --> 00:30:09.178
the skull icon

429
00:30:09.178 --> 00:30:11.928
So

430
00:30:16.178 --> 00:30:20.828
right-click

431
00:30:20.828 --> 00:30:23.378
 below the root and

432
00:30:25.078 --> 00:30:26.828
add a Socket

433
00:30:26.828 --> 00:30:29.128
to create a new socket there

434
00:30:29.128 --> 00:30:32.578
In the Details panel

435
00:30:35.178 --> 00:30:41.128
 I'll name the socket "GrabPoint" and position it where we want it to be

436
00:30:43.928 --> 00:30:52.678
Now, with the GrabPoint selected

437
00:30:52.678 --> 00:30:58.728
 I'll move it to align around the center of the hand, like this

438
00:30:59.628 --> 00:31:04.428
This looks about right

439
00:31:09.978 --> 00:31:13.778
If it's centered on the hand and facing upwards in the front direction

440
00:31:13.778 --> 00:31:18.428
the statue should be grabbed like this

441
00:31:18.428 --> 00:31:21.928
So, to match the shape of the hand

442
00:31:21.928 --> 00:31:26.278
we need to rotate it so that the front direction

443
00:31:26.278 --> 00:31:36.729
 points towards the front of the hand

444
00:31:36.729 --> 00:31:39.479
If you feel confused at any point

445
00:31:39.479 --> 00:31:42.379
you can attach a preview here to help visualize it beforehand

446
00:31:42.379 --> 00:31:45.379
You can add a preview asset here

447
00:31:45.379 --> 00:31:49.879
by clicking on "Add Preview Asset"

448
00:31:49.879 --> 00:31:51.579
and attaching the statue here as a mock-up

449
00:31:51.579 --> 00:31:53.529
The size might be a bit large

450
00:31:55.429 --> 00:31:58.829
 but you can adjust it to match the shape and orientation of the hand

451
00:31:58.829 --> 00:32:02.679
So, with this orientation

452
00:32:02.679 --> 00:32:05.479
we should adjust the Grab Point slightly downward, right?

453
00:32:05.479 --> 00:32:09.029
We should lower it slightly

454
00:32:09.029 --> 00:32:12.329
so that it aligns like this when grabbed

455
00:32:12.329 --> 00:32:13.929
considering that we actually reduced the size by half (0.5 scale)

456
00:32:13.929 --> 00:32:16.529
and adjusted accordingly

457
00:32:16.529 --> 00:32:19.129
I'll set the socket position

458
00:32:19.129 --> 00:32:23.579
like this for attachment

459
00:32:24.779 --> 00:32:30.779
save the rotation and position

460
00:32:30.779 --> 00:32:33.529
and copy the name "Grab Point" with Ctrl + C for the socket

461
00:32:33.529 --> 00:32:36.029
To make it easier

462
00:32:36.029 --> 00:32:38.579
let's go back to the Blueprint settings

463
00:32:38.579 --> 00:32:40.779
and in the Event Graph

464
00:32:40.779 --> 00:32:46.079
use Attach Actor To Component again

465
00:32:46.079 --> 00:32:49.979
but this time specify the socket name directly

466
00:32:49.979 --> 00:32:53.479
So, we'll specify the socket name as "GrabPoint" when attaching it

467
00:32:53.479 --> 00:32:56.629
 directly telling it to attach there

468
00:32:56.629 --> 00:33:00.179
Attach to the Grab Point socket on the Right Hand

469
00:33:00.179 --> 00:33:04.279
using Snap for both location and rotation

470
00:33:04.279 --> 00:33:06.329
We won't apply scaling

471
00:33:06.329 --> 00:33:08.679
We'll maintain the scale

472
00:33:08.679 --> 00:33:11.079
as it originally was for the object

473
00:33:12.529 --> 00:33:18.529
I'll compile, save, and then let's test grabbing it again

474
00:33:26.529 --> 00:33:29.679
How does it feel picking it up again now?

475
00:33:29.679 --> 00:33:33.279
Now it has become like this, fitting to my hand

476
00:33:33.279 --> 00:33:35.429
But it's a bit too high up, right?

477
00:33:35.429 --> 00:33:38.979
Because we lowered the statue a bit

478
00:33:38.979 --> 00:33:43.079
I think it would fit better if we raise it a bit

479
00:33:43.079 --> 00:33:48.679
So earlier, we lowered it from the hand socket

480
00:33:48.679 --> 00:33:51.329
but I'll try raising it a bit

481
00:33:51.329 --> 00:33:55.479
Shall we raise it about this much?

482
00:33:59.629 --> 00:34:01.279
Then, how about holding it like this again?

483
00:34:01.279 --> 00:34:06.429
Now it feels like we're really holding the statue

484
00:34:08.079 --> 00:34:12.079
Implementing the object placement function

485
00:34:12.579 --> 00:34:18.479
Now that we've grasped it, let's try placing it down once

486
00:34:18.479 --> 00:34:21.279
It's very easy to place it down

487
00:34:21.279 --> 00:34:24.129
When is the right time to put it down?

488
00:34:24.129 --> 00:34:29.279
When we've completed it, that's when we'll put it down, right?

489
00:34:35.179 --> 00:34:39.279
Use "Detach From Actor" to

490
00:34:39.279 --> 00:34:44.129
If you use "Detach From Actor,"

491
00:34:44.129 --> 00:34:47.729
you'll be able to detach what's currently attached

492
00:34:47.729 --> 00:34:50.079
When you detach something using "Detach From Actor,"

493
00:34:50.079 --> 00:34:51.779
 you can detach what's currently attached

494
00:34:51.779 --> 00:34:54.179
However, if you haven't saved or stored what you're currently holding

495
00:34:54.179 --> 00:34:58.129
you won't be able to detach it because the system doesn't remember what you were holding at that moment

496
00:34:58.129 --> 00:35:02.379
So, when you attach something here

497
00:35:02.379 --> 00:35:06.779
you'll save this attached actor to a variable

498
00:35:06.779 --> 00:35:09.779
You'll create a variable

499
00:35:11.979 --> 00:35:21.020
and name it something like "Current Grabbed Actor,"

500
00:35:21.020 --> 00:35:24.970
of type "BP Grab Object,"

501
00:35:24.970 --> 00:35:29.579
to store the actor you're currently holding

502
00:35:29.579 --> 00:35:31.929
And you'll select the actual object reference

503
00:35:31.929 --> 00:35:37.679
the Grab Object, for its Object Reference

504
00:35:37.679 --> 00:35:42.379
Compile and save to ensure the variable is compiled properly

505
00:35:42.379 --> 00:35:46.179
Then you'll set this variable

506
00:35:50.279 --> 00:35:52.229
When you set it

507
00:35:52.229 --> 00:35:55.279
you'll tidy up this Grabbed Actor

508
00:35:59.379 --> 00:36:01.229
 a bit beforehand

509
00:36:02.979 --> 00:36:07.879
We're going to save

510
00:36:07.879 --> 00:36:10.129
the currently attached actor

511
00:36:10.129 --> 00:36:11.729
 into the Current Grabbed Actor variable

512
00:36:11.729 --> 00:36:14.029
Then, when you grab an object

513
00:36:14.029 --> 00:36:16.879
the actual object you're holding will be stored in this variable, right?

514
00:36:16.879 --> 00:36:23.929
So, when you release it

515
00:36:23.929 --> 00:36:27.829
you'll retrieve it from Current Grabbed Actor and detach that actor

516
00:36:27.829 --> 00:36:31.029
When releasing it

517
00:36:31.029 --> 00:36:39.229
you'll detach it from its current position

518
00:36:39.229 --> 00:36:41.379
keeping it in the world coordinate system (Keep World)

519
00:36:41.379 --> 00:36:44.629
 so it drops from its current position without changing its original world coordinates

520
00:36:44.629 --> 00:36:46.579
If you just detach it without any additional actions

521
00:36:46.579 --> 00:36:48.479
it will remain suspended in the air

522
00:36:48.479 --> 00:36:51.579
Then you'll turn on physics again

523
00:36:51.579 --> 00:36:56.129
You'll set "Simulate Physics" on the box

524
00:37:03.979 --> 00:37:06.629
to turn physics simulation back on

525
00:37:08.179 --> 00:37:10.279
Compile and then save

526
00:37:12.829 --> 00:37:15.179
Should we test it out again?

527
00:37:17.520 --> 00:37:22.420
Press play, grab the object

528
00:37:22.420 --> 00:37:25.420
and now when you release it, it should drop like this

529
00:37:25.420 --> 00:37:30.479
Now you can grab and throw objects like this

530
00:37:32.479 --> 00:37:34.929
So, once you know how to grab

531
00:37:34.929 --> 00:37:38.329
 releasing is very easy

532
00:37:39.779 --> 00:37:43.779
Handling exceptions

533
00:37:44.179 --> 00:37:49.779
So, leaving it like this seems too complex

534
00:37:49.779 --> 00:37:52.729
so I'll refactor this into a function

535
00:37:52.729 --> 00:37:57.179
So, let's add a function

536
00:37:57.179 --> 00:38:03.279
I'll create a function named GrabAction

537
00:38:03.279 --> 00:38:05.529
Next, I'll create a function named GrabAction

538
00:38:05.529 --> 00:38:09.079
and then I'll cut out all the actions we did

539
00:38:09.079 --> 00:38:17.279
when we started from the Event Graph with Ctrl + X

540
00:38:17.279 --> 00:38:18.929
Next, I'll paste everything we cut with Ctrl + X

541
00:38:18.929 --> 00:38:25.379
into the GrabAction function

542
00:38:25.379 --> 00:38:28.279
and connect it accordingly

543
00:38:29.479 --> 00:38:32.729
Then, return to the Event Graph

544
00:38:32.729 --> 00:38:40.929
 and connect the GrabAction to the "Started" event

545
00:38:42.479 --> 00:38:45.779
Similarly, I'll create a function for releasing as well

546
00:38:45.779 --> 00:38:53.879
I'll create a function named ReleaseAction for releasing

547
00:38:53.879 --> 00:38:55.829
We had actions for

548
00:38:55.829 --> 00:38:57.629
when we completed the release in the Event Graph

549
00:38:57.629 --> 00:39:00.529
I'll cut those actions from the Event Graph with Ctrl + X

550
00:39:00.529 --> 00:39:03.179
paste them into the ReleaseAction function with Ctrl + V

551
00:39:03.179 --> 00:39:07.879
and connect the execution pin accordingly

552
00:39:07.879 --> 00:39:10.729
Then, return to the Event Graph

553
00:39:10.729 --> 00:39:14.179
and connect ReleaseAction

554
00:39:14.179 --> 00:39:16.179
to the "Completed" event

555
00:39:17.429 --> 00:39:20.179
Now it should be much cleaner and organized

556
00:39:20.179 --> 00:39:23.279
And now each functionality is neatly organized in its respective functions

557
00:39:23.279 --> 00:39:25.829
making it easier to review

558
00:39:25.829 --> 00:39:29.229
and understand each part

559
00:39:39.079 --> 00:39:41.929
 Let's wrap it up here for now then

560
00:39:41.929 --> 00:39:44.679
Let's work on

561
00:39:44.679 --> 00:39:47.029
adding movement functionality next time

562
00:39:47.029 --> 00:39:50.779
Thank you for your hard work and patience throughout this long session

563
00:39:51.529 --> 00:39:54.779
I'll summarize what we've learned in this session

564
00:39:54.779 --> 00:39:58.429
First, to attach an object to a Hand Component

565
00:39:58.429 --> 00:40:02.579
you need to use the "Attach Actor To Component" function node

566
00:40:02.579 --> 00:40:05.029
It's important to note that

567
00:40:05.029 --> 00:40:08.579
this can only be done

568
00:40:08.579 --> 00:40:10.879
when the "Simulate Physics" feature of the object you're attaching is set to false

569
00:40:10.879 --> 00:40:13.729
Secondly, when searching for objects that can be grabbed around the hand in VR

570
00:40:13.729 --> 00:40:17.529
it's important to note that

571
00:40:17.529 --> 00:40:19.929
the visual information in VR may not perfectly match the actual sense of distance for a person

572
00:40:19.929 --> 00:40:21.929
Therefore

573
00:40:21.929 --> 00:40:24.229
you should define

574
00:40:24.229 --> 00:40:27.379
the detection area slightly wider than

575
00:40:27.379 --> 00:40:29.929
the actual size of the hand

576
00:40:29.929 --> 00:40:33.329
Otherwise, users might feel uncomfortable when trying to grab objects

577
00:40:33.329 --> 00:40:35.579
as the virtual representation may not align perfectly with their real-world perception of reach and distance

578
00:40:35.579 --> 00:40:38.680
Lastly, the third point we covered is

579
00:40:38.680 --> 00:40:40.480
using the Axis values of buttons like the Index Trigger or Hand Trigger

580
00:40:40.480 --> 00:40:42.680
to smoothly animate the fingers of the hand mesh in response to button inputs

581
00:40:42.680 --> 00:40:45.280
This method simplifies handling

582
00:40:45.280 --> 00:40:47.280
and was demonstrated

583
00:40:47.280 --> 00:40:49.880
through

584
00:40:49.880 --> 00:40:51.929
practical exercises

585
00:40:52.730 --> 00:40:53.230
Applying Hand Animations
Preparing Input Functionality

586
00:40:53.230 --> 00:40:53.730
Create the IA_HandTrigger_Right file in the Inputs folder for handling object grabbing inputs
Set the Value type to Digital (Bool) for the IA_HandTrigger_Right file

587
00:40:53.730 --> 00:40:54.230
Inputs received for passing to the Hand Animation Blueprint
Create two files: IA_HandTriggerFloat_Right and IA_IndexTriggerFloat_Right

588
00:40:54.230 --> 00:40:54.730
Set the Value type to Axis1D (Float) to receive values corresponding to the degree of button press

589
00:40:54.730 --> 00:40:55.230
Implement functionality to pass input values to the hand animation
Double-click on the ABP_HunetHand file to open its settings window

590
00:40:55.230 --> 00:40:55.730
In the Animation Settings window of ABP_HunetHand, navigate to the Anim Preview Editor tab located in the bottom left corner

591
00:40:55.730 --> 00:40:56.230
Find the Default variables and adjust the Pose Alpha Grasp value to any random value between 0 and 1. Then, observe the animation to see it in motion

592
00:40:56.230 --> 00:40:56.730
Adjust the Pose Alpha Index Curl value to any random value between 0 and 1 to observe the movement of the index finger in the animation

593
00:40:56.730 --> 00:40:57.380
Implementing the object grabbing functionality
Creating the Grab Object

594
00:40:57.380 --> 00:40:58.080
In the Content Drawer, drag the SM_TableRound file from StarterContent - Props folder onto the viewport to place it

595
00:40:58.080 --> 00:40:58.730
Adjust the Scale value to 1.2 times to make it a comfortable height for picking up objects

596
00:40:58.730 --> 00:40:59.380
Apply gravity to the object so that it naturally falls downward when placed

597
00:40:59.380 --> 00:41:00.080
Select the Box component in the left Component panel
Check (True) the Simulate Physics property in the right Details panel

598
00:41:00.080 --> 00:41:00.730
Implement the Grab function
Keep World method, Snap to Target method

599
00:41:00.730 --> 00:41:01.230
Implement the drop object functionality
Implement the release function

600
00:41:01.230 --> 00:41:01.730
Drag the Completed execution pin of the IA_HandTrigger_Right input event node

601
00:41:01.730 --> 00:41:02.230
and connect it to the Detach From Actor node to detach the actor from its parent component

602
00:41:02.230 --> 00:41:02.730
Specify the Current Grabbed Actor variable, which was stored when grabbing the object, to detach

603
00:41:02.730 --> 00:41:03.230
Set Location Rule, Rotation Rule, and Scale Rule all to Keep World

604
00:41:03.230 --> 00:41:03.730
Call the Simulate Physics node on the Box component of the detached actor and check the Simulate property

605
00:41:03.730 --> 00:41:04.230
Since the object has been released, clear the value of the Current Grabbed Actor variable that was storing the grabbed object

606
00:41:04.230 --> 00:41:04.730
Play the game and confirm that when releasing the right hand trigger, the object drops and flies away

607
00:41:04.730 --> 00:41:05.230
Exception handling
Organizing Blueprint Node
Declare functions named 'GrabAction' and 'ReleaseAction'

608
00:41:05.230 --> 00:41:05.730
Move the grab function nodes connected to the Started execution pin of the IA_HandTrigger_Right node into the implementation of the Grab Action function node

609
00:41:05.730 --> 00:41:06.230
Similarly, move the release function nodes connected to the Completed execution pin into the implementation of the Release Action function node

610
00:41:06.230 --> 00:41:06.730
Handle preventing duplicate grabs

611
00:41:06.730 --> 00:41:07.230
To prevent grabbing overlapping objects, connect an Is Valid node in the Grab Action function node to execute detection

612
00:41:07.230 --> 00:41:07.730
only when the Current Grabbed Actor variable is initially empty

613
00:41:07.730 --> 00:41:08.230
Conversely, connect an Is Valid node at the beginning of the Release Action function implementation to execute the release function

614
00:41:08.230 --> 00:41:08.730
only when there is a held object (Current Grabbed Actor)