Unreal Engine Rendering

UE4 – HLSL texture sample quick tip

Posted on July 4, 2021July 5, 2021 by Oded Maoz Erell

Software:
Unreal Engine 4.26

When sampling textures using an HLSL custom node,
The UE4 TextureObject input name, will automatically have a sampler object generated named:

<your TextureObject name>sampler

For example, if you named your TextureObject input “tex_in”, the available sampler will be named “tex_insampler”.
So the code for sampling the texture will be:

Texture2DSample(tex_in, tex_inSampler, coords);

The following is an example of a simple u-blur custom node code, with 4 node inputs:
1. tex_in – TextureObject
2. coords – float2
3. size – float
4. sample – float

int blur_samples = int(samples * 0.5f);
float3 col = 0.0f;
float2 sample_coords = 0.0f;
for (int i = -blur_samples; i < blur_samples; i ++)
{	
	sample_coords.x = i * (size / blur_samples * 2);
	col += Texture2DSample(tex_in, tex_inSampler, coords + sample_coords ) / (blur_samples * 2);
}
return col;

The above code can typed directly in the Custom node’s Code field. or loaded from an external .usf file.

UE4 – Replace the Camera component icon

Posted on June 20, 2021July 26, 2021 by Oded Maoz Erell

Software:
Unreal Engine 4.26

Note:
This seems like an awkward workaround..
So if I missed something here, and there’s a better method to do this,
I’ll be very grateful is you share it in the comments.
Also,
The following tip is only relevant for the CineCameraActor and won’t work with a regular CameraActor as it has a different built in offset (hopefully, I’ll have time to add this to the post later..)

Replacing the camera icon:
Its fairly simple to replace the Camera component’s mesh icon,
Just select the component and replace it’s Camera Mesh Static Mesh component with a different static mesh object:

So what’s the problem?
The problem is that the default mesh used for the camera icon doesn’t have its natural pivot at the focal point of the camera, but at its bottom somewhere,
And there is a hardcoded transform offset that compensates for that and places the icon mesh in a way that has the Icon lens roughly at the actual Camera actor pivot / focal point:

* I haven’t found any exposed transform parameter that allows moving the icon itself without moving the camera.
So in-order to replace the camera mesh with an alternative icon mesh, and have it be aligned properly to the camera’s pivot / focal point (without changing engine code and building it) the built-in offset must be negatively pre-added to the new mesh model:

In this example in Blender, a new icon is modeled facing positive Y, with pre-built offset to compensate for the hardcoded offset in UE.

The Camera actor with the alternative Icon:

Note:
In this example, I’ve replaced the camera icon with a much smaller model, intentionally, to suite a tiny scale project,
You can also scale the icon without replacing the model.

UE4 – Loading shaders from within the project folder

Posted on March 22, 2021May 7, 2022 by Oded Maoz Erell

Software:
Unreal Engine 4.25
*Also tested on Unreal Engine 5.0.1

Disclaimer:
I’m probably the 10th guy that’s documenting these steps on the web,
I didn’t come up with this solution myself, I learned it from the sources listed below.
The reason I’m documenting this (again) myself is to have a clear source I can come back to for this issue because I’m absolutely incapable of remembering subjects like this…… :-\
If you find inaccuracies in the steps I’m detailing or my explanation, I’ll be very grateful if you share a comment.

In short:
AFAIK since version 4.21 UE doesn’t load custom node shader code from your project/Shaders folder by default anymore, but only from the shaders folder in the engine installation, which makes it less practical for developing shaders for specific projects.

Steps for setting the UE project to load shaders from the project folder in UE 4.22:

> The examples here are for a project named: “Tech_Lab”

A. The project must be a C++ project:

So either create a new project, define as such or just create a new C++ class and compile the project with it to convert it to a C++ project.
Notes:
a. You may need to right click the .uproject file icon and and Generate Visual Studio Project Files for the project to load correctly into Visual Studio and compile.
b. You can delete the unneeded C++ class you added after the new settings took place.

B. Create a folder for the shader files:

Typically, it will be called “Shaders” and will be placed in the project root folder.

C. Add the RenderCore module to the project:

This is done by adding string “RenderCore” to array of public dependency modules in the <project>.build.cs file:

PublicDependencyModuleNames.AddRange(new string[] { "RenderCore", "Core", "CoreUObject", "Engine", "InputCore" });
(see image)

Notes:
a. In UE 4.21 it should be ShaderCore.
b. This addition is needed in-order to compile a new primary project module (next step).

D. Define a custom primary module for your project:

In <project_name>.h file add a new module named F<project_name>Module, with a StartupModule function overrides.
Notes:
a. We have add an include statement for “Modules/ModuleManager”.
b. The <project_name>.h file is located in the /Source/<project_name> folder.
c. Some sources state that you also have to override the ShutdownModule function, with an empty override, it works for me without this (maybe its just a mistake..)

E. Implement the function override,
and set the custom module as the project primary module:

In <project_name>.cpp file, add the StartupModule override,
With the definition of the added shaders path:
FString ShaderDirectory = FPaths::Combine(FPaths::ProjectDir(), TEXT("Shaders"));

and mapping this new path as “/Project” for conveniently including it:
AddShaderSourceDirectoryMapping("/Project", ShaderDirectory);

Last thing to do is to replace “FDefaultGameModuleImpl” with our custom module name in the IMPLEMENT_PRIMARY_GAME_MODULE macro:
IMPLEMENT_PRIMARY_GAME_MODULE(FTech_LabModule, Tech_Lab, "Tech_Lab" );

Notes:
a. We must include “Misc/Paths”
b. Note that the addition of this folder mapping is restricted to versions 4.22 and higher via a compiler directive condition. for version 4.21, you should state “ENGINE_MINOR_VERSION >= 21:

Note for UE5:
Unreal Engine 5 supports this from the get go so this compiler directive condition should be deleted for this to work.

F. Wrapping up:

After taking these steps and compiling the project.
You should be able to include .ush and .usf files stored in <your_ue_project>/Shaders with the “Project” path mapping:
include "/Project/test.usf"

That’s it! 🙂

I hope you found this helpful,
And if you encountered errors, or inaccuracies,
I’ll be grateful if you’ll take the time to comment.

Related:

UE4 – Technical model visualization tips

Posted on July 6, 2020July 7, 2020 by Oded Maoz Erell

Software:
Unreal Engine 4.25

This post is a summary of the tips given by Epic Games technical-artist Min Oh in his GDC 2017 lecture about improving photo-realism in product visualization, more specifically, how to render high quality surfaces.
I recommend watching the full lecture:

Render sharper reflections by increasing the Cubemap resolution of reflection captures:
Project Settings > Engine > Rendering > Reflection > Reflection Capture Resolution
* use powers of 2 values i.e. 256, 512, 1024….
Improve the accuracy of environment lighting by increasing the Cubemap resolution of the Skylight:
* use powers of 2 values i.e. 256, 512, 1024….
Improve screen space effects accuracy like screen space reflections by setting the engine to compute high precision normals for the GBuffer:
Set Project Settings > Engine > Rendering > Optimizations > GBuffer Format to:
High Precision Normals
Use a high degree of tessellation (subdivision) for the models pre-import.
Simpy put:
Use high quality models.
Improve the surfaces tangent space accuracy, and as a result also the shading/reflection accuracy by setting the model’s static mesh components to encode high precision tangent basis:
Static Mesh Editor > Details > LOD 0 > Build Settings > Use High Precision Tangent basis
Creating materials with rich dual specular layers by enabling material clear coat separate normal input:
Project Settings > Engine > Rendering > Materials > Clear Coat Enable Second Normal
Set the material Shading Model to Clear Coat and use a ClearCoatBottomNormal input node to add a normal map for the underlying layer:

Related:

UE4 – Enable DXR Raytracing

Posted on July 5, 2020July 6, 2020 by Oded Maoz Erell

Software:
Unreal Engine 4.25

Steps for activating DXR Ray-tracing in a UE4 project:

Project Settings:
Platforms > Windows > Targeted RHIs:
Set Default RHI to DirectX 12
* RHI = Rendering Hardware Interface
Project Settings:
Engine > Rendering > Ray Tracing:
Check Ray Tracing
* Requires restarting the editor, and may take a while to load the project afterwards..
* I’m actually not sure if the reason for delay in re-launching the project is a full re-build of the lighting or compiling shaders..
Post Process Volume > Rendering Features > Reflections:
Set Type to: Ray Tracing
Post Process Volume > Rendering Features > Ray Tracing Reflections:
Set Max Bounces to more than 1 if needed

No DXR Reflections:

DXR Reflections on a GTX 1070 GPU:

Related posts:

UE4 – Lighting calculation tips for Archviz

Posted on July 4, 2020July 5, 2020 by Oded Maoz Erell

Software:
Unreal Engine 4.25

The Static Lighting calculation in UE4 is performed by the Lightmass module (UE4’s integrated GI* engine), and the result of this calculation is stored in each object’s Lightmap, an extra texture map used for storing static light and shadow information.
This post provides a list of useful tips and techniques for improving your UE4 scene setup for an efficient light calculation.

Annotation 2020-07-04 223338

Notes:

The following tips are aimed at achieving a good lighting calculation/solution but they don’t include optimization methods for high performance projects.
Namely, we don’t get into manual Lightmap UV optimizations here.
The following tips don’t take into account the now real-time ray-tracing options that have become available with Nvidia Geforce RTX / DirectX DXR.

Scene Setup:

Delete unseen polygons from your mesh, so they wont waste Lightmap resolution.
* For example, in an interior Archviz project, delete the outer polygons of the walls.
Set the architectural surfaces to cast shadows from both sides:
Details > Lighting > Shadow Two Sided
Place “light blockers” around the structure to avoid light licks.
* Wrap the structure on all sides with scaled cubes that have an absolute black material:
Set the “light blockers” to be invisible in rendering:
Scale the Lightmass Importance Volume fit around the structure tightly.

Lightmap Resolution:

Optimize the architectural surfaces (static meshes) Light map resolution.
A higher resolution will allow the Light Map to store more detailed lighting.
The Static Mesh resolution setting is found in:
Static Mesh Edior > Details > General Settings > Light Map Resolution:
* This setting can also be overriden at the actor settings by selecting the actor in the map/level and activating:
Details > Lighting > Override Lightmap Res
Use the Lightmap Density optimization display mode to inspect the actual Lightmap texel density.
The Lightmap Density display mode also color codes the display to indicate the efficiency of the Lightmap resolution per object (green color being optimal, and warm colors being too dense)
* Note that in many cases of Archviz you may want a higher density than the editor displays as optimal.

Lighmass Settings:
The Lightmass setting are found in:
World Settings > Lightmass

Decrease the Volumetric Lightmap Detail Cell Size to increase the light calculation accuracy:
* This will increase the calculation time
Decrease the Indirect Lighting smoothness to get more detailed shadows:
Disable Compress Lightmaps to avoid banding artifacts in the shadow gradient:
Use the Lighting Only display mode to evaluate the lighting solution:
For final quality, set the Light Quality to Production:
Build menu > Lighting Quality > Production

* GI – “Global Illumination” is a term referring to indirect light simulation, namely a calculation of how light reflects and bounces between surfaces.

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