user: Describe GreasePencilEnvelopeModifier(Modifier) from the Blender manual or Python API, including usage steps and snippets.

assistant: # GreasePencilEnvelopeModifier(Modifier)

base classes — [`bpy_struct`](bpy.types.bpy_struct.html#bpy.types.bpy_struct "bpy.types.bpy_struct"), [`Modifier`](bpy.types.Modifier.html#bpy.types.Modifier "bpy.types.Modifier")

*class* bpy.types.GreasePencilEnvelopeModifier(*Modifier*)
:   Envelope stroke effect modifier

    invert_layer_filter
    :   Invert layer filter

        Type:
        :   boolean, default False

    invert_layer_pass_filter
    :   Invert layer pass filter

        Type:
        :   boolean, default False

    invert_material_filter
    :   Invert material filter

        Type:
        :   boolean, default False

    invert_material_pass_filter
    :   Invert material pass filter

        Type:
        :   boolean, default False

    invert_vertex_group
    :   Invert vertex group weights

        Type:
        :   boolean, default False

    layer_pass_filter
    :   Layer pass filter

        Type:
        :   int in [0, 100], default 0

    mat_nr
    :   The material to use for the new strokes

        Type:
        :   int in [-1, 32767], default -1

    material_filter
    :   Material used for filtering

        Type:
        :   [`Material`](bpy.types.Material.html#bpy.types.Material "bpy.types.Material")

    material_pass_filter
    :   Material pass

        Type:
        :   int in [0, 100], default 0

    mode
    :   Algorithm to use for generating the envelope

        - `DEFORM`
          Deform – Deform the stroke to best match the envelope shape.
        - `SEGMENTS`
          Segments – Add segments to create the envelope. Keep the original stroke..
        - `FILLS`
          Fills – Add fill segments to create the envelope. Don’t keep the original stroke..

        Type:
        :   enum in [`'DEFORM'`, `'SEGMENTS'`, `'FILLS'`], default `'SEGMENTS'`

    open_influence_panel
    :   Type:
        :   boolean, default False

    skip
    :   The number of generated segments to skip to reduce complexity

        Type:
        :   int in [0, inf], default 0

    spread
    :   The number of points to skip to create straight segments

        Type:
        :   int in [1, inf], default 10

    strength
    :   Multiplier for the strength of the new strokes

        Type:
        :   float in [0, inf], default 1.0

    thickness
    :   Multiplier for the thickness of the new strokes

        Type:
        :   float in [0, inf], default 1.0

    tree_node_filter
    :   Layer name

        Type:
        :   string, default “”, (never None)

    use_layer_group_filter
    :   Filter by layer group name

        Type:
        :   boolean, default False

    use_layer_pass_filter
    :   Use layer pass filter

        Type:
        :   boolean, default False

    use_material_pass_filter
    :   Use material pass filter

        Type:
        :   boolean, default False

    vertex_group_name
    :   Vertex group name for modulating the deform

        Type:
        :   string, default “”, (never None)

    *classmethod* bl_rna_get_subclass(*id*, *default=None*, */*)
    :   Parameters:
        :   **id** (*str*) – The RNA type identifier.

        Returns:
        :   The RNA type or default when not found.

        Return type:
        :   [`bpy.types.Struct`](bpy.types.Struct.html#bpy.types.Struct "bpy.types.Struct") subclass

    *classmethod* bl_rna_get_subclass_py(*id*, *default=None*, */*)
    :   Parameters:
        :   **id** (*str*) – The RNA type identifier.

        Returns:
        :   The class or default when not found.

        Return type:
        :   type