Unreal Engine – Oded Erell's CG Log

UE4 – Blueprints – Set Parent Class

Posted on March 22, 2020March 22, 2020 by Oded Erell

Software:
Unreal Engine 4.24

When It comes to OOP inheritance, the best practice is to take a moment to think about code structure and decide which classes should be be extensions of a common super-class. But in a wild hackathon or game-jam, we may be blueprinting too hastily for that, and we may find out different blueprint classes actually have to be child classes of a common parent class after they already exist and have existing blueprints in them.
In this case will have to Set their parent class as a different class than the class we chose when we initially created them, and also create calls to the parent class event functions if needed.

Setting a BP’s parent class:

Click Class Settings, and under Class Options, in the Parent Class drop-down select the wanted parent class (superclass).

Calling the Parent Class’s event functions:

Note:
When creating a BP class that is defined as child class in its creation this is done automatically

Right-Click the current class’s Event icon, and select Add call to parent function:
Connect the execution flow graph, and other inputs if necessary:

UE4 Blueprints – Spawn Actor Transform Note..

Posted on March 22, 2020March 22, 2020 by Oded Erell

Software:
Unreal Engine 4.24

Short version:
When Spawning new actors via the SpanActor Blueprint node, initial transform must be supplied to the SpanActor node, and not defined in the spawned Actor Class’s Blueprint.

Annotation 2020-03-22 131138

Explanation:
Just found out the hard way, that when you spawn an Actor using the SpawnActor blueprint node, the transform data connected to the SpawnActor node is actually applied after the actors Construction Script and BeginPlay Event.
This means any transform you will try to apply in the spawned Actor’s Blueprint will be overridden and therefore not work.

UE4 – First Person Projectile Overlap Event

Posted on March 14, 2020 by Oded Erell

Software:
Unreal Engine 4.24

Had some frustrating time not understanding why doesn’t the FirstPersonProjectile Actor doesn’t “play ball” and generate Overlap Events when hitting my bad guys..
It turns out I had to change its collision (sphere) component’s collision settings to overlap dynamic objects (see image):

UE4 Material Blueprint Shortcuts

Posted on December 26, 2019January 16, 2020 by Oded Erell

Software:
Unreal\n Engine 4.24

Some useful Unreal Editor Material Blueprint shortcuts:

Hold 1 and LMB Click to create a 1D Constant node:
Hold 2 and LMB Click to create a 2D Constant node:
Hold 3 and LMB Click to create a 3D Constant node:
Hold S and LMB Click to create a Scalar Parameter node:
Hold V and LMB Click to create a Vector Parameter node:
Hold L and LMB Click to create a Lerp (Linear Interpolate) node:
Hold M and LMB Click to create a Multiply node:
Hold A and LMB Click to create a Add node:
Hold T and LMB Click to create a Texture Sample node:
Hold U and LMB Click to create a Texture Coordinate node:
Just press C to create a comment:

More UE4 Material Editing posts

UE4 – Basic Material Blending

Posted on December 26, 2019January 7, 2020 by Oded Erell

Software:
Unreal Engine 4.24

The example explained in this article is creating a blend between a mud material, and a mud-leaves material using a mask (Alpha) texture.
>> The scanned PBR materials in demonstrated in this post are from Texture Haven (texturehaven.com)

How does it work?
There is actually no blending of Unreal materials, but rather a regular Unreal material in which each of the parameters is defined as a linear blend between 2 different source values for that parameter.
We could create such a material blueprint that uses a Lerp (Linear Interpolate) node’s to provide each of the material parameters with a blend of 2 input textures/colors or parameters, connecting the alpha texture to all the Lerp nodes’s Alpha input, and effectively achieve blending of 2 different materials, but it would be a complex blueprint in which it’s very inconvenient to design each of the individual materials participating in the blend:

This complexity can be greatly simplified by collecting each of the participating materials parameters into a Material Attributes data structure.
The Material Attributes data structure contains all the data needed to compile a material, and allows input, output, and processing of this data as a single blueprint data stream (connection).
For example, when the material parameters are grouped as a Material Attributes data structure, they can be blended by connecting them into a single BlendMaterialAttributes node, instead of “Lerping” (blending) between 2 inputs to create each individual material parameter, which produces an unworkable complex material blueprint like the previous example.

> To collect material parameters into a Material Attributes data structure, connect them into a MakeMaterialAttributes node:

> To create a blend between 2 Material Attributes data streams, use the BlendMaterialAttributes node:
* The Alpha parameter determines the weights of the blend (a black and white texture can be connected to it as the blend mask)

> In order for the material output to receive a grouped Material attributes input instead of individual inputs for each parameter, select the material output, and in the Details panel, check the Use Material Attributes option:

Using the Material Attributes data structure, the blended material’s Blueprint in now much simpler and cleaner, while producing the exact same result as before:

But designing 2 different materials within one material Blueprint is still far from being ideal..
What if we want to use just one of these materials on some surfaces?
What if the individual materials are not as simple as the materials shown here, it would be mush more efficient to be able to have one Blueprint for each of the materials allowing to focus on its development and preview it.
We can achieve this desired workflow by developing each of the materials as a Material Function.
Each of the participating materials is created as a Material Function with a Material Attributes output.

> One of the huge advantages of UE4’s material editing is that it allows us to preview a full material while developing it as a Material Function.
* This may sound trivial, but it isn’t. the Material Function isn’t compiled by itself as a material, it just produces data needed to define a material. in many other media production systems, this would have meant that you can develop data within the function but only preview it in the main material where the function is used.

> Learn how to create Material Functions

The Material Function defining the mud material:

The Material Function defining the mud-leaves material:
Annotation 2019-12-26 024906.jpg

The Blend material using the Material Function nodes:

Note:
When blending a non-metallic material with a metal material, the alpha values (mask colors) should be only 0 or 1 (black or white), otherwise blend areas that have a mid-range metallic value will make no sense visually.
> A RemapValueRange node can be used to force a color threshold on the mask texture or value.

UE4 – Material Functions explanation and Example

Posted on December 24, 2019December 26, 2019 by Oded Erell

Software:
Unreal Engine 4.24

Material Functions encapsulate shading flow graphs (material blueprints) into reusable shading nodes that have their own inputs and outputs.
This allows development of custom shading nodes, and saving the time it takes to recreate the same flow graphs multiple times or even copy and paste material flow graphs.
Common shading processes and operations that have to be performed in many different materials, and even multiple times in a single material can be defined as a Material Function for quick and easy re-usability.
Material functions can also be used to encapsulate a full material blueprint with a Material Attributes output. this provides a convenient workflow for blending different materials together.

In this post I’ll detail the steps needed to create and use a Material Function.
The Material Function example we’ll create, called “ColorAngleBlend” performs a commonly needed shading operation of blending 2 colors or textures according to the surface viewing angle (facing ratio).

The ColorAngleBlend Material Function will have the following inputs:

color a:
The color or texture appearing when viewing the surface at perpendicular angle.
color b:
The color or texture appearing when viewing the surface at grazing view angle.
curve exponent:
The steepness of the blend curve between the colors, 1 being a linear blend and higher values displaying color a at more angles “pushing” color b to be seen only at grazing angle.
base color blend:
The percent of color b seen at perpendicular view angle.
normal:
bump normals input.

The final “ColorAngleBlend” Material Function Blueprint:
* The internals of the “ColorAngleBlend” Material Function

An example of the “ColorAngleBlend” Material Function node used to create a reach view-angle dependent color blend for a steampunk metal material:

An example of the “ColorAngleBlend” Material Function node used to create a reach color for a car-paint material:

An example of the “ColorAngleBlend” Material Function node used to create a washed-out effect for a cloth material:
Steps for creating the “ColorAngleBlend” Material Function:

In the content browser, create a Material Function Object and name it “ColorAngleBlend”:
Double click the ColorAngleBlend Material Function to open it for editing:
Click the background of the work space to deselect the Output Result Node,
So that the Details panel on the left will display the Material Functions‘s properties.
Type a description into the Description field, check the Expose to Library option so that the new Material Function will be available to all materials in the Palate and node search, and define in which node categories it should appear:
Select the Output Result node and in the Details panel on the left set its output name to “color”:
Add a Linear Interpolate (Lerp) node, a Fresnel node and a Transform Vector (Tangent space to World space) node to the Blueprint and connect the nodes like this:
* The Lerp node will blend the 2 color inputs with the Fresnel providing view angle data as the alpha for the Lerp.
The Transform Vector node is needed to convert normal (bump) input to world space for the Fresnel node.
Adding function inputs:
Create 2 Function Input nodes, in their Details panel, name them “color a” and “color b”, leave their Input Type as default Vector3D, check the option Use Preview Value as Default, number their Sort Priority parameters 0 and 1 to make them appear as the first inputs of the ColorAngleBlend node as it will appear when used in a material, and connect them to the Lerp node’s A and B inputs:
Adding function inputs:
Create 2 new Function Input nodes, name them “curve exponent” and “base color blend”, this time set their Input Type to Scalar, check the option Use Preview Value as Default, set their Sort Priority parameters to 2 and 3 and connect their outputs to the Fresnel node’s ExpoentIn and BaseReflectFractionIn inputs:
Adding function inputs:
Create the final Function Input node, name it “normal“, set its Input Type to Vector3D, check its Preview Value as Default option, set its Sort Priority to 4, and connect its output to the Fresnel node’s Normal input:
Adding default inputs:
Finally, add constant nodes to serve as default input values for the Material Function.
A pure white Constant3Vector (color) constant as the default value for “color a” input,
A pure black Constant3Vector (color) constant as the default value for “color a” input,
A Constant with value 1.0 as the default value for “curve exponent” input,
A Constant with value 0.0 as the default value for”base color blend” input,
A pure blue Constant3Vector (color) constant as the default value for “normal” input.
> Tip for quick creation of constant value nodes
Save the new Material Function.

To use the new ColorAngleBlend Material Function create a new material, in the node search start typing color… to locate the ColorAngleBlend node and create it, and connect it to the desired material input.

Annotation 2019-12-24 173809.jpg

> Material Functions can also be used by dragging them from the Content Browser into the Material Blueprint.

Related posts:
UE4 Material Instances
UE4 Fresnel node

UE4 – RemapValueRange Node

Posted on December 23, 2019December 24, 2019 by Oded Erell

Software:
Unreal Engine 4.24

Having to remap a value range is very common in designing shaders, whether it’s to perform a traditional “levels” operation on a texture, or use just a specific range of values in a float input.
The RemapValueRange node let’s us do just that. this node has 5 inputs:

Input: The input value
Input Low: Input mapping range minimum
Input High: Input mapping range maximum
Target Low: Output range minimum
Target Height: Output range maximum

Mono Noise examples:

The original noise pattern:
Mapping input 0 -> 1 to output 0 -> 1 obviously has no effect:
Mapping input 0 -> 1 to output 0.3 -> 0.7 reduces the pattern contrast:
Mapping input 0.3 -> 0.7 to output 0 -> 1 increases the pattern contrast:
Mapping input 0 -> 1 to output 1 -> 0 inverts the pattern:

In this example RemapValueRange nodes are applied to a texture’s individual color channels to increase contrast (Levels):
> Note that this operation can be performed using a simpler graph by using float3d adding and multiplication operations on the texture color (this will be a subject for a different post)
> Note that a different remapping operation can be performed on each color channel of a texture to adjust its color balance.

Before the value remapping:

After the value remapping tha value in each channel 0.1 -> 0.9 to 0.0 to 1.0:

The same operation performed by multiplication by 1.2 and subtracting 0.1: