UE4 – Using a Post Process material to create a simple fog effect

Software:
Unreal Engine 4.24

An example of a simple fog effect created using a Post Process material:

 

The fog material Blueprint:
The method for creating the fog effect is to take distance of the objects from the camera, map it to a value range suitable for color blending 0 – 1, and use that for blending the object’s color with the fog color, so the further away the object, the more it will be colored by the fog.
Start by creating a new material, and follow the details below to create the Blueprint:

Fog_PP_material

  1. The Material Domain is set to Post Process.
    And has its Blendable Location parameter set to Before Tonemapping so it will be applied on the raw render.
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  2. A SceneTexture node with its Scene Texture Id parameter set to PostProcessInput0 serves as the input of the view’s original rendered pixel colors:
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  3. A Lerp (LinearInterpolate) node calculates the blending of the view’s original pixel colors with the Fog color to create the fog effect.
  4. A SceneTexture node with its Scene Texture Id parameter set to SceneDepth serves as the input of depth of each pixel (distance from camera):
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  5. A ComponentMask node set to the R channel allows using the depth data as a single float value instead of a Vector4:
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  6. A Clamp node is used to clamp (limit) the depth value to the Fog’s maximum depth value (see below)
  7. A RemapValueRange maps the distance value to a fog density value that will be used as the Lerp (3) alpha parameter.
    Simply put, the further the object, the more the original color will be blended with the fog color.
  8. A Power node (raises the fog blend factor by an exponent) make the fog blending non-linear, that is beginning gently for closer objects and than increasing more drastically as the distance grows (provided that the exponent value is above 1)
  9. A Constant Vector4 serves as an input for the fog color.
    * Note that having this input be a Vector4 and not a Vector3 allows it to be interpolated with the PostProcessInput0 data, otherwise a ComponentMask (RGB) node would have been necessary to convert the PostProcessInput0 to a Vector3.
  10. a float constant serves as an input for the fog’s minimal distance (from camera)
  11. a float constant serves as an input for the fog’s maximal distance (from camera)
    *  Note that it’s connected both to the Clamp node and to the RemapValueRange node.
  12. a float constant serves as an input for the fog’s minimal opacity (blend amount)
  13. a float constant serves as an input for the fog’s maximal opacity (blend amount)
  14. a float constant serves as an input for the fog’s blend exponent.

 

Applying the Post Process material to the level:

Fog_2

  1. Select the PostProcessVolume actor in the World Outliner window.
    * Create a PostProcessVolume actor if necessary.
  2. In the Details panel, under Rendering Features > Post Process materials,
    Add a new item to the array, in the new item’s value choose Asset Reference,
    And then select your fog material:
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Related:

  1. Material Functions
  2. Blending materials
  3. Blending materials using texture paint

UE4 – Change the size of the UI and fonts

Software:
Unreal Engine 4.24

To Change the size of the UI and fonts in the Unreal Editor:

  1. Select:
    Window > Developer Tools > Widget Reflector
    To open the Widget Reflector window
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  2. In the Widget Reflector window, change the Application Scale parameter:
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UE4 Blueprints – Spawn Actor Transform Note..

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.

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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

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):
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UE4 Material Blueprint Shortcuts

Software:
Unreal\n Engine 4.24

Some useful Unreal Editor Material Blueprint shortcuts:

  1. Hold 1 and LMB Click to create a 1D Constant node:
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  2. Hold 2 and LMB Click to create a 2D Constant node:
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  3. Hold 3 and LMB Click to create a 3D Constant node:
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  4. Hold S and LMB Click to create a Scalar Parameter node:
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  5. Hold V and LMB Click to create a Vector Parameter node:
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  6. Hold L and LMB Click to create a Lerp (Linear Interpolate) node:Annotation 2019-12-26 005653
  7. Hold M and LMB Click to create a Multiply node:
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  8. Hold A and LMB Click to create a Add node:
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  9. Hold T and LMB Click to create a Texture Sample node:Annotation 2019-12-26 010504
  10. Hold U and LMB Click to create a Texture Coordinate node:
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  11. Just press C to create a comment:
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More UE4 Material Editing posts

UE4 – Enable complex collision for models

Software:
Unreal Engine 4.21

By default UE4 uses fast simplified convex collision shapes to calculate collision for static mesh actors.
This means that the player or projectiles wont be able to path through holes, openings or doors in the model.

To set complex (concave) collision for a static mesh model:

In Static Mesh editing window, in the details pane, under Collision:
Set Collision Complexity to: Use Complex Collision As Simple

Static_Mesh_Complex_Collision.jpg

This example shows the default behavior for a model that has an opening, neither the projectiles nor the player can pass:

Simple_Collision.gif

In this example collision for the model was set to Use Complex Collision As Simple:

Complex_Collision.gif

 

Vector Parameters in the UE4 Material Blueprint

Software:
Unreal Engine 4.18

UE4 Material Blueprint Numerical Vector Parameters / Constants and Colors are one and the same, which makes perfects sense, since in computer graphics colors are in fact 3D vectors, RGB quantities being equivalent to XYZ spatial dimensions (4D with an Alpha channel)

But take note that when setting the Vector values in the color picker you can’t set negative values, and when doing so through the Details window in Default Value you can.

* You can create 3D Vector Constants by clicking the background while pressing 3

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