Function and Helper

Function and GraphFunction let you move reusable logic out of raw Graph statements. Use Function for HLSL-style computation, and GraphFunction when the helper needs to create or call Unreal graph nodes through UE.*.

Basic Declaration

Function float Luma(vec3 color)
{
    return dot(color, vec3(0.2126, 0.7152, 0.0722));
}

Use it from Graph code:

Graph = {
    float y = Luma(Tint);
}

Multiple Outputs

Multi-output helpers use out parameters:

Function void SplitColor(vec3 color, out float r, out float g, out float b)
{
    r = color.r;
    g = color.g;
    b = color.b;
}

Call multi-output helpers with explicit variables:

Graph = {
    float r;
    float g;
    float b;
    SplitColor(Tint, r, g, b);
}

GraphFunction

GraphFunction can call UE.* inside its body:

GraphFunction float Pulse(float speed)
{
    float t = UE.Time();
    return sin(t * speed) * 0.5 + 0.5;
}

The generator turns UE.Time() into a graph node and wires it into the Custom node used for the helper.

Texture Parameters

When helpers sample textures, keep texture and sampler-like inputs explicit. Editor metadata from the VSCode extension includes Unreal texture sampling helpers and common HLSL intrinsics.

Function vec3 ApplyTint(vec3 color, vec3 tint)
{
    return color * tint;
}

Function Builtins

VSCode extension 1.4.9 unifies metadata for:

The compiler side still follows DreamShaderLang's supported syntax and generator rules.

Normal vs Self-contained Functions

Use a normal Function when the helper can be emitted as shared HLSL. Use a SelfContained helper when the generated Custom-node code needs to carry its own helper body and avoid relying on external generated includes.

SelfContained Function float SaturatePulse(float x)
{
    return saturate(sin(x) * 0.5 + 0.5);
}

Namespaced Functions

Functions can be grouped in a namespace:

Namespace ColorTools
{
    Function float Luma(vec3 color)
    {
        return dot(color, vec3(0.2126, 0.7152, 0.0722));
    }
}

Call:

float y = ColorTools::Luma(Tint);

Design Suggestions

Common Errors