HLSL Overview

HLSL is the shader language used by Unreal's material Custom nodes. DreamShaderLang borrows some HLSL-style types and helper-function syntax, but Graph code still generates Unreal material nodes.

Basic Shape

float Luma(float3 color)
{
    return dot(color, float3(0.2126, 0.7152, 0.0722));
}

Common Types

HLSL	DreamShaderLang equivalent
`float`	`float`
`float2`	`float2` / `vec2`
`float3`	`float3` / `vec3`
`float4`	`float4` / `vec4`
`Texture2D`	`Texture2D`

Variables and Expressions

float3 tinted = color * tint;
float y = saturate(tinted.r);

DreamShaderLang Function bodies use familiar HLSL-style expressions for helper logic.

Control Flow

if (x > 0.5)
{
    return 1.0;
}
return 0.0;

Complex control flow is best placed in Function, not directly in Graph.

Common Builtins

Function	Use
`dot`	Dot product.
`lerp`	Linear interpolation.
`saturate`	Clamp to `0..1`.
`sin`, `cos`	Trigonometry.
`normalize`	Normalize a vector.

Common Keywords

Keyword	Meaning
`return`	Return a function value.
`if`, `else`	Conditional flow.
`for`, `while`	Loop constructs in helper code when supported.
`out`	Output parameter.
`inout`	Input/output parameter.

Relation to DreamShaderLang

HLSL area	DreamShaderLang usage
Helper functions	`Function` and `GraphFunction` bodies.
Vector math	Graph expressions and helpers.
Raw node graph	Use `Graph` and `UE.*`, not plain HLSL.
Material settings	Use `Settings`, not HLSL code.