Materials

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Verbs for editing Material expression graphs and setting parameter overrides on MaterialInstanceConstant assets. Material graph verbs operate on expression indices (integers) rather than GUIDs.

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Material graph verbs (7)#

mat-list-expressions#

List all expressions in a Material asset.

Category: Read

Arg	Required	Description
-asset=	Yes	Material asset path

Examples:

-verb=mat-list-expressions -asset=/Game/Materials/M_Base

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mat-add-expression#

Add an expression node to a Material graph.

Category: Write (material)

Arg	Required	Description
-asset=	Yes	Material asset path
-class=	Yes	Expression class (short name or full suffix, e.g., ScalarParameter, VectorParameter, TextureSample, Multiply, Add, Constant, Lerp)
-posX=	No	X position
-posY=	No	Y position
-name=	No	Parameter name (for parameter expressions like ScalarParameter, VectorParameter)

Examples:

-verb=mat-add-expression -asset=/Game/Materials/M_Base -class=ScalarParameter -name=Roughness -posX=0 -posY=0
-verb=mat-add-expression -asset=/Game/Materials/M_Base -class=VectorParameter -name=BaseColor -posX=0 -posY=200
-verb=mat-add-expression -asset=/Game/Materials/M_Base -class=TextureSample -posX=-400 -posY=0
-verb=mat-add-expression -asset=/Game/Materials/M_Base -class=Multiply -posX=-200 -posY=100
-verb=mat-add-expression -asset=/Game/Materials/M_Base -class=Lerp -posX=-200 -posY=300
-verb=mat-add-expression -asset=/Game/Materials/M_Base -class=Constant -posX=-400 -posY=200

Notes:

• -name= is only meaningful for parameter expression types (ScalarParameter, VectorParameter, TextureParameter). It is ignored for non-parameter types like Multiply or Constant.
• The returned expression index is used by mat-connect, mat-connect-property, and mat-delete-expression.

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mat-connect#

Connect two material expression outputs to inputs.

Category: Write (material)

Arg	Required	Description
-asset=	Yes	Material asset path
-srcExpression=	Yes	Source expression index (integer)
-dstExpression=	Yes	Destination expression index (integer)
-srcOutput=	No	Source output pin name (defaults to first/empty)
-dstInput=	No	Destination input pin name (defaults to first/empty)

Examples:

# Connect expression 0 output to expression 1 input (both default pins)
-verb=mat-connect -asset=/Game/Materials/M_Base -srcExpression=0 -dstExpression=1

# Connect specific pins
-verb=mat-connect -asset=/Game/Materials/M_Base -srcExpression=0 -dstExpression=2 -srcOutput=RGB -dstInput=A

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mat-connect-property#

Connect an expression to a material property input (e.g., BaseColor, Roughness).

Category: Write (material)

Arg	Required	Description
-asset=	Yes	Material asset path
-expression=	Yes	Expression index (integer)
-property=	Yes	Material property name (see supported values below)
-output=	No	Expression output pin name (defaults to first)

Supported property values: BaseColor, Metallic, Specular, Roughness, Normal, EmissiveColor, Opacity, OpacityMask, WorldPositionOffset, AmbientOcclusion, SubsurfaceColor

Examples:

# Wire a VectorParameter to BaseColor
-verb=mat-connect-property -asset=/Game/Materials/M_Base -expression=0 -property=BaseColor

# Wire a ScalarParameter to Roughness
-verb=mat-connect-property -asset=/Game/Materials/M_Base -expression=1 -property=Roughness

# Wire the RGB output of a texture sample to Normal
-verb=mat-connect-property -asset=/Game/Materials/M_Base -expression=3 -property=Normal -output=RGB

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mat-delete-expression#

Delete a material expression by index.

Category: Write (material)

Arg	Required	Description
-asset=	Yes	Material asset path
-expression=	Yes	Expression index (integer)

Examples:

-verb=mat-delete-expression -asset=/Game/Materials/M_Base -expression=2 -save

Notes:

• Connections involving the deleted expression are broken automatically.
• Expression indices of remaining nodes may shift after deletion. Use mat-list-expressions to get updated indices.

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mat-recompile#

Recompile a material and its shaders.

Category: Write (material)

Arg	Required	Description
-asset=	Yes	Material asset path

Examples:

-verb=mat-recompile -asset=/Game/Materials/M_Base

Notes:

• Use after making structural changes (adding/removing expressions, changing connections) to ensure shader compilation is up to date.
• Recompilation can take several seconds for complex materials.

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MaterialInstance verbs (2)#

mi-list-params#

List all parameter overrides on a MaterialInstanceConstant.

Category: Read

Arg	Required	Description
-asset=	Yes	MaterialInstance asset path

Examples:

-verb=mi-list-params -asset=/Game/Materials/MI_Base_Red

Output:

{
    "success": true,
    "parameters": [
        { "name": "BaseColor", "type": "vector", "value": "(R=1.0,G=0.0,B=0.0,A=1.0)" },
        { "name": "Roughness", "type": "scalar", "value": "0.4" },
        { "name": "UseDetail", "type": "staticswitch", "value": "false" }
    ]
}

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mi-set-param#

Set a parameter value on a MaterialInstanceConstant.

Category: Write (material instance)

Arg	Required	Description
-asset=	Yes	MaterialInstance asset path
-name=	Yes	Parameter name
-value=	Yes	Value string (see format table below)
-paramType=	No	Force type: scalar, vector, texture, staticswitch. Auto-detected if omitted.

Value formats by type:

Type	Format	Example
scalar	Decimal number	"0.5"
vector	UE struct text	"(R=1.0,G=0.5,B=0.0,A=1.0)"
texture	Asset path	"/Game/Textures/T_Rock_D"
staticswitch	Boolean string	"true" or "false"

Examples:

# Set a scalar parameter
-verb=mi-set-param -asset=/Game/Materials/MI_Base_Red -name=Roughness -value=0.8 -save

# Set a vector (color) parameter
-verb=mi-set-param -asset=/Game/Materials/MI_Base_Red -name=BaseColor -value="(R=0.2,G=0.4,B=1.0,A=1.0)" -save

# Set a texture parameter
-verb=mi-set-param -asset=/Game/Materials/MI_Base_Red -name=DiffuseTexture -value=/Game/Textures/T_Metal_D -save

# Set a static switch parameter
-verb=mi-set-param -asset=/Game/Materials/MI_Base_Red -name=UseDetail -value=true -save

# Force type detection when auto-detection fails
-verb=mi-set-param -asset=/Game/Materials/MI_Base_Red -name=Emissive -value=1.0 -paramType=scalar -save

Notes:

• Type is auto-detected from the parent material's parameter definitions when -paramType= is omitted.
• Use -paramType= when the parameter name is ambiguous or the auto-detection picks the wrong type.

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Batch example: create a material with expressions wired to properties#

Build a PBR material from scratch with ScalarParameter and VectorParameter nodes connected to material property inputs, all in a single commandlet launch.

{
    "defaultAsset": "/Game/Materials/M_NewPBR",
    "operations": [
        {
            "verb": "mat-add-expression",
            "args": { "class": "VectorParameter", "name": "BaseColor", "posX": "-400", "posY": "0" },
            "id": "basecolor"
        },
        {
            "verb": "mat-add-expression",
            "args": { "class": "ScalarParameter", "name": "Metallic", "posX": "-400", "posY": "200" },
            "id": "metallic"
        },
        {
            "verb": "mat-add-expression",
            "args": { "class": "ScalarParameter", "name": "Roughness", "posX": "-400", "posY": "400" },
            "id": "roughness"
        },
        {
            "verb": "mat-add-expression",
            "args": { "class": "TextureSample", "posX": "-600", "posY": "600" },
            "id": "normaltex"
        },
        {
            "verb": "mat-connect-property",
            "args": { "expression": "$basecolor.expressionIndex", "property": "BaseColor" }
        },
        {
            "verb": "mat-connect-property",
            "args": { "expression": "$metallic.expressionIndex", "property": "Metallic" }
        },
        {
            "verb": "mat-connect-property",
            "args": { "expression": "$roughness.expressionIndex", "property": "Roughness" }
        },
        {
            "verb": "mat-connect-property",
            "args": { "expression": "$normaltex.expressionIndex", "property": "Normal", "output": "RGB" }
        },
        { "verb": "mat-recompile" }
    ],
    "save": true
}

This creates four expression nodes (BaseColor vector parameter, Metallic scalar parameter, Roughness scalar parameter, and a texture sample for the normal map), wires each to the corresponding material property input, recompiles shaders, and saves the asset.

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Tips#

• Use mat-list-expressions before writes. Expression indices can change after adding or deleting nodes. Always refresh the index list before connecting or deleting.
• Batch for multi-step material edits. Each commandlet launch loads the full editor. Use batch operations to avoid repeated 30-60 second startup costs.
• mat-recompile after structural changes. Adding expressions or changing connections requires recompilation to update shaders.
• mi-set-param for instance variation. Create MaterialInstances from a parent Material, then use mi-set-param to override specific parameters without duplicating the entire material graph.