Global distance field sample in Custom node problems

So there is this really simple setup to just read the distance field and write it to Emissive colour.

No custom node

What I would like to do is acces this same information inside of a custom node.

float3 GlobalUV = ComputeGlobalUV(WorldPosition, 0);
float DistanceToSurface = 0;
DistanceToSurface = Texture3DSampleLevel(GlobalDistanceFieldTexture0, SharedGlobalDistanceFieldSampler0, GlobalUV, 0).x;
return DistanceToSurface;

This works, but only partially.

The results show up in preview viewports, and in the global distance field, and mesh distance field visualisation modes, but not in the main viewport.

Default Viewmode

SDF Visualisation mode

If anyone has any ideas, that would be super appreciated.

Hi Wyvery,

Try to put a float instead of a Sampler in your second input. Maybe that’s helps.

Texture3DSampleLevel(GlobalDistanceFieldTexture0, (float instead of sampler), GlobalUV, 0).x;

Here is link for this function.


Hey yunus, thank you for your reply!

That’s a very good suggestion, I hadn’t thought to try it.
Unfortunately this also doesn’t work.

First of all the link you sent is for Texture3D::SampleLevel, not Texture3DSampleLevel.
Or in other words, the function shouldn’t become
Texture3DSampleLevel(GlobalDistanceFieldTexture0, (float instead of sampler), GlobalUV, 0).x;
GlobalDistanceFieldTexture0.SampleLevel(SharedGlobalDistanceFieldSampler0, GlobalUV, 0).x;
Minor problem, mostly just saying this for people coming here from google searching for a similar problem
GlobalDistanceFieldTexture0 is my texture3D object here.

I believe Texture3DSampleLevel(Texture3D, samplerState, float, float [,int]) might just be a function in unreal to wrap the function you showed.

This code compiles, but the same issue still persists.

I tried a few other things while I’m at it.
When using the DistanceToNearestSurface node, this code gets generated.

So with the custom node this would be replaced by my custom expression

Where I call the same function

I ran this through a code compare tool and the lines I’m showing are the only differences between the two
shaders. Except for that, the two shaders are identical.

Yet the issue still persists


Hey Wyvery,

you are welcome!

I see…

i guess the “Get Distance To Nearest Surface Global” is included by any function library.
You will find the “include” files and the path in the upper part of your hlsl code.
Mostly this include file collecting a bunch of functions also macros etc or other methods.

I hope this will help.

It’s part of GlobalDistanceFieldShared.ush
I opened this file inside of vs and copied over the code from there originally, that’s where the ComputeGlobalUV and Texture3DSampleLevel Functions came from.

1 Like