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UE3 to UE4 Transition Guide - Epic Wiki

# UE3 to UE4 Transition Guide

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# Contents

# Overview

Here you can find a list of procedure and terminology differences between UDK and Unreal Engine 4 gathered by the community. Keep in mind that some of those may be subject to change in time with newer UE4 releases.

# General Editor & Terminology

Scene Scale(Units)

UE3: 1uu == 2cm

UE4: 1uu == 1cm

UE3: World size = 10.48km x 10.48km

UE4: World size = 20km x 20km

Assets and Packages

UE3: Packages are used to store a collection of assets. Package format .upk - Map format .udk

UE4: Each asset is stored in its own file. Maps are still packages as they need to store a collection of assets. Asset format .uasset - Map format .umap

Mesh/Skeletal Mesh & Animation Import Formats

UE3: .psk & .psa / .FBX
Collision naming : MyMesh, UCX_MyCollision

UE4: .FBX(same Export procedure - Mesh and Skeleton split into 2 separate asset after import)
Collision naming : MyMesh, UCX_MyMesh_## (_## is a number in case you have several UCX in there)

Disabling Decal Render on Skeletal/Static Meshes:

UE3: Go to decal properties (F4) and disable bProjectOn.

UE4: Select your Mesh in Viewport.

  1. In details panel search for Decal
  2. Uncheck Receives Decals.

Spline Loft Actor

UE3: Created by dragging and dropping from Actor Classes tab. Continue drawing a path by holding Alt and dragging the icon.

UE4: It appears in the landscape editor as Spline Tools when you create a landscape. Click Manage > Edit Splines > Ctrl+click to place one then continue drawing by placing control points with Ctrl+click, finally hit Apply Settings button in the landscape editor.

Collision Terminology

UE3: Touch and Block

UE4: Overlap and Block

# Editor

Navigation, Maya Style

considering UDK <=> UE3

UE3: L + left or right mouse button

UE4: Alt + left or right mouse button

# Kismet > Blueprints(Matinee included)

Creating a Matinee

UE3: Open Kismet, right-click the canvas and select New Matinee.

UE4: Search for MatineeActor in Modes tab > All Classes, and drag it into your level.

Attaching Actors to Specific Groups inside Matinee

UE3: Create a variable for the object inside Kismet and attach it to Matinee.

UE4: Select the object in the map, open up Matinee, right click on the group you want to attach > Actors > Add(or replace) selected actors.

Sequential or random activation of multiple outputs

UDK: Switch node in Kismet.

UE4: MultiGate node in Blueprints.

# Lighting

Adding a SkyLight

UE3= Actor Classes - Lights - Sky Lights

UE4= Modes Tab > Lights > Sky Light

Adding a dynamic light

UE3= Actor Classes > Lights > AnyLightMoveable.

UE4= Add a normal light into your level - in the settings you can find Transform > Mobility > Moveable.

Lightmaps and photons

UE3= Emissive material enabled in object in the level, photons will fire from any shape: material based.

UE4= For dynamic emissive lighting, needs to be enabled in advanced material properties(for LPV.) For static emissive lighting, enable Use Emissive for Static Lighting in the object's details panel.

# Materials

Subsurface Scattering

UE3: Achieved with transmission mask

UE4: Achieved with SubsurfaceColor - choose MLM_Subsurface in the Lighting Mode

Adjusting a Particle's Color in Cascade

UE3: By multiplying the texture with a Vertex Color node in the material.

UE4: By multiplying the texture with a Particle Color node in the material.

Soft Edge for Particles and Translucent Materials

UE3: Attach the opacity mask to Alpha input of DepthBiasedAlpha and set Bias scale for fade distance.

UE4: Attach the opacity mask to Opacity input of DepthFade and set Fade Distance.

Colored Speculars

UE3: By pluging the colored specular texture to Specular input.

UE4: By giving metallic value(Constant - 1) to the material

# Coding

Spawning Actors

UE3:

var Actor MyActor;

MyActor = Spawn(class'ActorToSpawn',Location,Rotation);

UE4:

FActorSpawnParameters SpawnInfo; SpawnInfo.bNoCollisionFail = true;

ASoulHunterWeapon* NewWeapon = GetWorld()->SpawnActor(Weapon, SpawnInfo);

There are several versions of Spawn one with and without templates.

If you want to use location and rotation make sure you make variables that are const.

const FVector* SLocation; const FRotator* SRotation;

GetWorld()->SpawnActor(Weapon, SLocation, SRotation, SpawnInfo);

Spawning Objects

This can be used to create instances (or more accurately, pointers to instances of) classes derived from Object.

UE3:

var MyObject MyObjectRef;

MyObject = new class'MyObject';

UE4:

In YourClass.h:

UPROPERTY() MyObject *MyObjectRef;

In YourClass.cpp:

MyObjectRef = NewObject(this, UMyObject::StaticClass());

Also see Documentation - Objects for a detailed description.

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