Houdini Engine for 3ds Max
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Data Marshalling

Houdini Engine for 3ds Max is capable of marshalling data between Houdini and 3ds Max. This section will provide a description of both the inputs (from 3ds Max to Houdini) and the outputs (from Houdini to 3ds Max) that the plugin is capable of marshalling between the two programs.

Mesh Inputs

This section describes the data that gets marshalled into Houdini when you provide any geometry input to an HDA. The "3ds Max Input" column explains what the input is. The "Houdini Attribute" column provides the name of the attribute within Houdini that gets used for the input. The "Attribute Type" column indicates whether it is a point, vertex, primitive, or detail attribute. The "Description" column is used for any additional information.

3ds Max Input Houdini Attribute Attribute Type Description
Normals N Vertex Standard normal marshalling
Smoothing Groups hemax_sg Primitive Marshalls the smoothing groups for the mesh's faces
UV Layers uv ... uv99 Vertex The plugin will marshall any UV layers that it finds. The first UV layer is placed in the "uv" layer, and any subsequent uv layers are appended with a number indicating the layer
Soft Selection soft_selection Point Marshalls any soft selections the user has made
Colors Cd Vertex or Point Marshalls any vertex colors. This will be placed in either a vertex or point attribute depending on if the number of color inputs equals the number of points or equals the number of vertices
Alpha Alpha Vertex or Point Marshalls any vertex alpha values. This will be placed in either a vertex or point attribute depending on if the number of alpha inputs equals the number of points or equals the number of vertices
Illumination illumination Vertex or Point Marshalls any illumination values. This will be placed in either a vertex or point attribute depending on if the number of illumination inputs equals the number of points or equals the number of vertices
Material ID hemax_matid Primitive Marshalls the 3ds Max material ID for each face
Material Path hemax_material Primitive If there is a material on the input, this will marshall the material path. When the material is a multi-material, this attribute will store the name of the sub-material that is applied to the mesh face.
Material Path hemax_material Detail If the input object has a multi-material applied, this attribute will contain the name of the multi-material. The names of the sub-materials will be stored in the hemax_material primitive attribute.
Node Name hemax_node_name Detail The 3ds Max node name.

Mesh Input Groups

Additionally, the plugin will marshal some data into Houdini as groups:

3ds Max Input Group Name Group Type Description
Group See the description Point If the 3ds Max node belongs to a group, a point group will be created with the same name as the most immediate head group node.
Vertex Selection hemax_vertex_selection Point Group membership indicates whether the point (vertex in 3ds Max) is selected in 3ds Max. 1 indicates that the point is selected, and 0 indicates that the point is not selected.
Face/Element Selection hemax_face_selection Primitive Group membership indicates whether the primitive (face in 3ds Max) is selected in 3ds Max (either individually as a face or as a subset of an element selection). 1 indicates that the primitive is selected, and 0 indicates that the primitive is not selected.
Edge Selection hemax_edge_selection Point Edge selections must currently be sent to Houdini as a point group, which can then be promoted to a proper edge group by an HDA. Group membership indicates whether the point (vertex in 3ds Max) belongs to a selected edge in 3ds Max. 1 indicates that the point is part of a selected edge, 0 indicates that the point is not part of a selected edge.

Mesh Outputs

This section describes the data that gets marshalled into a 3ds Max polygonal mesh from Houdini. The "Houdini Attribute" column indicates the name of the attribute that the plugin will look for when creating the display geometry. The "Attribute Type" column indicates what type of attribute that attribute can be. The "3ds Max Output" column indicates where that attribute will be used. The "Description" column is used for any additional information.

Houdini Attribute Attribute Type 3ds Max Output Description
N Vertex Specified Vertex Normals Standard normal marshalling
uv, uv2 ... uv99 Vertex or Point UV Map The plugin will create a UV map for each UV layer.
hemax_sg Primitive Smoothing Groups Creates smoothing groups on each face of the 3ds Max mesh
hemax_matid Primitive Material IDs Creates material IDs on each face of the 3ds Max mesh
Cd Vertex or Point Color Map The plugin will create a color map. The number of faces in the map will always match the number of faces in the mesh. The number of vertices in the map will either be the number of points or the number of vertices (depending on if it is a vertex or point attribute).
Alpha Vertex or Point Alpha Map The plugin will create an alpha map. The number of faces in the map will always match the number of faces in the mesh. The number of vertices in the map will either be the number of points or the number of vertices (depending on if it is a vertex or point attribute).
Illumination Vertex or Point Illumination Map The plugin will create an illumination map. The number of faces in the map will always match the number of faces in the mesh. The number of vertices in the map will either be the number of points or the number of vertices (depending on if it is a vertex or point attribute).
hemax_material Detail Assigned material on object This allows you to specify the material to assign the object. See the Materials section for more information.
hemax_node_name_output Detail or Primitive INode Name The name of the outputted 3ds Max INode will be overridden with the value of this detail attribute. This attribute can also be used as a primitive attribute to override the node name of geometry created from packed primitives.
hemax_bake_layer_name Detail Layer Name The value of this attribute overrides the default name of the scene layer that gets created when baking a geometry HDA.
hemax_bake_parent_node_name Detail Node Name When baking a geometry HDA, the value of this attribute overrides the default name of the baked parent node.
meta_* Detail User Defined Properties This detail attribute prefix can be used to create user defined properties on the 3ds Max object. Any detail attributes with this prefix will be added, with the attribute name and value forming the key/value pair of the user defined property.

Mesh Output Groups

Additionally, the plugin will marshal some data into 3ds Max from Houdini groups:

3ds Max Output Group Name Group Type Description
Vertex Selection hemax_vertex_selection Point This group controls whether the 3ds Max vertex of the generated geometry will be selected. When the point is a member of the group, the vertex will be selected in 3ds Max.
Face Selection hemax_face_selection Primitive This group controls whether the 3ds Max face of the generated geometry will be selected. When the primitive is a member of the group, the face will be selected in 3ds Max.
Edge Selection hemax_edge_selection Point This group controls which edges of the generated 3ds Max geometry will be selected. In order for an edge to be selected in 3ds Max, both points that comprise the edge must be a member of the group.

Spline Inputs

This section describes the data that gets marshalled into a Houdini curve when a 3ds Max spline is provided as an input to an HDA.

3ds Max Input Houdini Attribute Attribute Type Description
Material ID hemax_matid Point This attribute stores the material ID of the 3ds Max spline segment that starts at the corresponding point.

Spline Outputs

This section describes the data that gets marshalled into a 3ds Max spline from a polygonal curve output of an HDA.

Houdini Attribute Attribute Type 3ds Max Output Description
hemax_matid Point Spline segment material IDs Sets the material ID of the 3ds Max spline segment that starts at the corresponding point.

Curve Inputs

This section describes the data that gets marshalled into a Houdini curve when a 3ds Max curve is provided as an input to an HDA.

3ds Max Input Houdini Attribute Attribute Type Description
Material ID hemax_matid Detail This attribute stores the material ID of the 3ds Max curve.

Curve Outputs

This section describes the data that gets marshalled into a 3ds Max curve from a NURBS curve output of an HDA.

Houdini Attribute Attribute Type 3ds Max Output Description
hemax_matid Detail Curve material ID Sets the material ID of the 3ds Max curve