Unreal custom node in which our HLSL code is placed has useful properties for defines and include paths.

This allows for more possibilities when creating hlsl material functions including usage of .ush files.

This pull request adds ability to set those properties for all functions in library as well as update function on changes to included files.

As just adding those properties was very easy most of the code changes are related to watching for changes in includes and supporting that properly.

Those changes fix compilation on UE5.0 release branch.

Pretty minor but had to fully disable permutation window feature and do a little hack in 8b86ea6335547965f558ebe9064ca59b8da88fc5 to keep support for UE5 Early Access.

One of the main limitations of the custom node is that it doesn't allow for multiple functions to be defined/used in a single node. A workaround exists where functions can be defined within a struct.

It would be awesome if the plugin could perform this process automatically, such that functions get automatically wrapped into a struct and calls to functions are swapped for calls to the function within the struct. Or alternatively, there may be a better workaround.

At the current state adding structs to the code breaks parsing, especially structs with functions which is the only easy way of adding non-material function "libraries" to the code node in UE4, i.e:

struct Functions 
{
    float4 SomeLocalFunction(float4 A, float4 B)
    {
        return lerp(A, B, 0.25);
    } 
};


void MaterialFunc(
    float4 A,
    float4 B
    out float4 Color)
{
    Functions fun;

    Color = fun.SomeLocalFunction(A, B);
}

If file contains multiple material functions, structs will be added to all of the code nodes.

When UHLSLMaterialFunctionLibrary::OnDirectoryChanged is called array of FFileChangeData has paths that are always full, not relative.

Filepath in HLSLMaterialFunctionLibrary is stored as relative filepath when possible. Which is good as this allowes for having shared hlsl directory in the project for all project users.

But when OnDirectoryChanged is called with those full paths it fails to find matching files.

With this change GetFilePath always returns full, not relative path

I met these matters:

• when using include, UE5 only supports .usf or .ush
• simply using #include "basic.usf" does not work, how to write the correct path so UE can find it?

When parsing includes in hlsl file all of them are added even if they are guarded by failed #ifdef

#include "header_a.ush"

#ifndef SOMEDEF
#include "header_b.ush"
#endif

Right now both header_a and header_b are included and this leads to compilation errors.

Hey, me again 😄

I propose small improvement to includes parsing that allows working with paths that IDEs have less problems with.

When using IDEs like Rider for developing shaders they often have problems with finding includes when included as virtual paths.

See for example https://youtrack.jetbrains.com/issue/RIDER-69615

This can be often worked around when working with global shaders by using relative paths to virtual shader location.

This cannot be done same way for code generated with HLSLMaterial.

This change adds fallback mechanism when we find that include path isn't real virtual path. We try to check if this path is relative path to our hlsl file and if it is we try to find it in virtual mappings.

Ideally this plugin would be able to differentiate between content that needs to definitely be part of a Custom node and everything else in order to take advantage of constant folding.

Function code:

void testFunc(float3 color, float intensity, out float3 diffuse, out float x) {

	float val = 0.1;
	int i = 0;
	while ( i <= 10 ) {
		diffuse.x = (val * (float)i);
		i += 1;
	}

	x = intensity * 0.5;
}

• Generated graph:

• Expected format: Intensity parameter and X output are not used within the while loop, and therefore could be broken out from the custom node: