neuray API Programmer's Manual

mi::neuraylib::ITriangle_connectivity Class Reference

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Description

A connectivity class for triangle mesh geometry and their attributes. A triangle connectivity maps vertices of a triangle mesh to indices. The vertices of the triangle mesh are identified by a pair of a triangle handle and a (local) vertex index in [0,3). Connectivities may have attached attribute vectors which use the connectivity information.

The meaning of the index associated with each vertex of the mesh is as follows: If the connectivity is the mesh connectivity, then this index identifies the point that belongs to a given vertex. Otherwise, the connectivity is called custom connectivity, and the index identifies an entry in an attribute vector that is associated with the given vertex. Note that attribute vectors can also be attached to the mesh connectivity (in which case an entry in the attribute vector is associated with the point mapped to the given vertex).

Attributes that have the same topological layout as the geometry typically use the mesh connectivity, e.g., normals for every point in the mesh. It is also possible to use an attribute connectivity with the same mapping as the mesh connectivity, however, using the mesh connectivity is more efficient. The use of a separate custom connectivity is necessary if the topological layout of the attribute is different from the geometry, e.g., for texture spaces with seams. Custom connectivities can also be useful to reduce the size of the attribute vector by sharing the same attribute value, e.g., for sharing the same normal between many points because of flat regions in the mesh.

Since the number of triangles is dictated by the mesh that the connectivity is associated with, it can only be changed by corresponding calls to the mi::neuraylib::ITriangle_mesh instance. It is possible to add points and triangles and to set the indices of the connectivities in alternating order, if so desired. The only constraint is that the largest connectivity index is smaller than the number of points (for the mesh connectivity) and smaller than the sizes of the attached attribute vectors (for all connectivities).

To create mesh attributes with the same connectivity, you can use a single connectivity and attach all these attribute to the same connectivity. However, when the mesh is retrieved from the DB no guarantee is given whether the attributes still share the connectivity or not.

Note:

You must not release the mesh from which this connectivity was obtained before you release the connectivity.

See also:

mi::neuraylib::ITriangle_mesh

mi::neuraylib::IAttribute_vector

mi::base::Interface_declare\< ... \>Mixin class template for deriving new interface declarations. The basic extensible interface.The basic extensible interface.

Methods related to the mapping represented by the connectivity

virtual Uint32 get_triangle_index( Triangle_handle_struct t, Uint32 vertex) const =0
Returns the index at the vertex vertex of triangle t. More...
virtual bool  is_valid_connectivity() const =0
Indicates whether this connectivity is valid. More...
virtual Sint32 set_triangle_indices( Triangle_handle_struct t, const Uint32* indices) =0
Sets the vertex indices of a triangle. More...
virtual Sint32 set_triangle_indices( Triangle_handle_struct t, Uint32 v0, Uint32 v1, Uint32 v2) =0
Sets the vertex indices of a triangle. More...
virtual Sint32 set_triangle_indices( Triangle_handle_struct t, const Triangle_point_indices_struct& triangle) =0
Sets the vertex indices of a triangle. More...
virtual Triangle_point_indices_struct triangle_point_indices( Triangle_handle_struct t) const =0
Returns the indices for all three vertices of triangle t. More...
virtual Uint32 triangles_size() const =0
Returns the number of triangles.

Methods related to the attached mesh attributes

virtual const IAttribute_vector* access_attribute_vector( Mesh_attribute_name name) const =0
Returns a non-per-primitive mesh attribute. More...
virtual Sint32 attach_attribute_vector( IAttribute_vector* attr) =0
Attaches a given non-per-primitive mesh attribute to the mesh. More...
virtual IAttribute_vector* create_attribute_vector( Mesh_attribute_name name, Uint32 dim = 1) const =0
Creates a non-per-primitive mesh attribute. More...
virtual IAttribute_vector* edit_attribute_vector( Mesh_attribute_name name) =0
Detaches and returns a non-per-primitive mesh attribute. More...
virtual bool  has_attribute( Mesh_attribute_name name) const =0
Indicates whether the connectivity has a particular mesh attribute. More...
virtual Sint32 remove_attribute_vector( Mesh_attribute_name name) =0
Removes a non-per-primitive mesh attribute. More...

Miscellaneous methods

virtual Connectivity_map_type get_map_type() const =0
Returns the type of the connectivity. More...

Member Functions

virtual const IAttribute_vector* mi::​neuraylib::​ITriangle_connectivity::access_attribute_vector( Mesh_attribute_name name) const [pure virtual]

Returns a non-per-primitive mesh attribute.

Parameters

name
The name of the attribute, see Mesh_attribute_name. The attribute must not be a per-primitive attribute.

Returns

The requested attribute vector, or NULL in case of failure.

virtual Sint32 mi::​neuraylib::​ITriangle_connectivity::attach_attribute_vector( IAttribute_vector* attr) [pure virtual]

Attaches a given non-per-primitive mesh attribute to the mesh. The attribute vector must not be used any longer after it has been attached.

See also:

create_attribute_vector(), edit_attribute_vector()

Returns

  • 0: Success.
  • -1: Invalid parameters (NULL pointer).
  • -2: The attribute vector has not been acquired from this connectivity.
  • -3: An attribute of the same name is already attached to the mesh (or to one of its connectivities).
  • -4: The connectivity is invalid.
  • -5: The attribute vector is too small for this connectivity.
virtual IAttribute_vector* mi::​neuraylib::​ITriangle_connectivity::create_attribute_vector( Mesh_attribute_name name, Uint32 dim = 1) const [pure virtual]

Creates a non-per-primitive mesh attribute. The attribute is not yet attached to the connectivity. It needs to be attached before it is released.

Note:

It is possible to create multiple attribute vectors on the same connectivity. If this connectivity is not the mesh connectivity, i.e., the attribute is not per point, but per vertex, then the connectivity information will eventually be duplicated such that each attribute vector has its own copy. This duplication happens after re-attaching the connectivity, but before it is stored in the database or the edit cycle ends.

See also:

attach_attribute_vector()

Parameters

name
The name of the attribute, see Mesh_attribute_name. The attribute must not be a per-primitive attribute.
dim
Dimension of an attribute value. Only used for those attributes that have user specifiable dimensions.

Returns

The requested attribute vector, or NULL in case of failure.

virtual IAttribute_vector* mi::​neuraylib::​ITriangle_connectivity::edit_attribute_vector( Mesh_attribute_name name) [pure virtual]

Detaches and returns a non-per-primitive mesh attribute. The attribute needs to be reattached before it is released. Otherwise, the attribute is effectively removed from the connectivity.

See also:

attach_attribute_vector()

Parameters

name
The name of the attribute, see Mesh_attribute_name. The attribute must not be a per-primitive attribute.

Returns

The requested attribute vector, or NULL in case of failure.

virtual Connectivity_map_type mi::​neuraylib::​ITriangle_connectivity::get_map_type() const [pure virtual]

Returns the type of the connectivity. Currently, only one type is supported.

virtual Uint32 mi::​neuraylib::​ITriangle_connectivity::get_triangle_index( Triangle_handle_struct t, Uint32 vertex) const [pure virtual]

Returns the index at the vertex vertex of triangle t.

Returns

The requested vertex index, or 0 if t is out of bounds, or vertex is not in the range [0,3).

virtual bool mi::​neuraylib::​ITriangle_connectivity::has_attribute( Mesh_attribute_name name) const [pure virtual]

Indicates whether the connectivity has a particular mesh attribute.

Parameters

name
The name of the attribute to query, see Mesh_attribute_name.

Returns

true if the connectivity has this attribute, false otherwise.

virtual bool mi::​neuraylib::​ITriangle_connectivity::is_valid_connectivity() const [pure virtual]

Indicates whether this connectivity is valid. A connectivity becomes invalid after it has been (re)attached to the corresponding mesh and may no longer been used.

virtual Sint32 mi::​neuraylib::​ITriangle_connectivity::remove_attribute_vector( Mesh_attribute_name name) [pure virtual]

Removes a non-per-primitive mesh attribute.

Parameters

name
The name of the attribute, see Mesh_attribute_name. The attribute must not be a per-primitive attribute.

Returns

  • 0: Success.
  • -1: There is no mesh attribute of that name on this connectivity, or the connectivity is invalid.
virtual Sint32 mi::​neuraylib::​ITriangle_connectivity::set_triangle_indices( Triangle_handle_struct t, const Uint32* indices) [pure virtual]

Sets the vertex indices of a triangle.

Note:

For best performance it is recommended to sort the triangles by their material index such that when looping over all triangles the material index changes as infrequently as possible.

Parameters

t
The triangle to modify.
indices
The new indices for triangle t.

Returns

  • 0: Success.
  • -1: Invalid parameters (NULL pointer).
  • -3: t is out of bounds.
  • -4: The connectivity is no longer valid.
virtual Sint32 mi::​neuraylib::​ITriangle_connectivity::set_triangle_indices( Triangle_handle_struct t, Uint32 v0, Uint32 v1, Uint32 v2) [pure virtual]

Sets the vertex indices of a triangle.

Note:

For best performance it is recommended to sort the triangles by their material index such that when looping over all triangles the material index changes as infrequently as possible.

Parameters

t
The triangle to modify.
v0
The first new index of triangle t.
v1
The second new index of triangle t.
v2
The third new index of triangle t.

Returns

  • 0: Success.
  • -3: t is out of bounds.
  • -4: The connectivity is no longer valid.
virtual Sint32 mi::​neuraylib::​ITriangle_connectivity::set_triangle_indices( Triangle_handle_struct t, const Triangle_point_indices_struct& triangle) [pure virtual]

Sets the vertex indices of a triangle.

Note:

For best performance it is recommended to sort the triangles by their material index such that when looping over all triangles the material index changes as infrequently as possible.

Parameters

t
The triangle to modify.
triangle
The new indices for triangle t.

Returns

  • 0: Success.
  • -3: t is out of bounds.
  • -4: The connectivity is no longer valid.
virtual Triangle_point_indices_struct mi::​neuraylib::​ITriangle_connectivity::triangle_point_indices( Triangle_handle_struct t) const [pure virtual]

Returns the indices for all three vertices of triangle t.

Returns

The requested indices, or a defaulted constructed return value if t is out of bounds.

virtual Uint32 mi::​neuraylib::​ITriangle_connectivity::triangles_size() const [pure virtual]

Returns the number of triangles.