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Drake
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Drake
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Definition of a general (possibly non-convex) mesh.
The mesh may be a triangular surface mesh or a tetrahedral volume mesh, depending on how it used.
Meshes can be used with all three roles but, currently, the support for the proximity role is limited. Where a general mesh is not supported, the mesh is replaced by its convex hull. See the documentation of QueryObject's proximity queries for more details. The notable cases where the actual mesh topology is used includes:
This convex-hull substitution is a regrettable stop-gap solution until we fully support general, non-convex meshes throughout proximity queries.
For visual roles (illustration and perception), the specified mesh file is used as directly as possible.
The mesh is defined in a canonical frame C, implicit in the file parsed. Upon loading it in SceneGraph it can be scaled around the origin of C by a given scale amount.
Note: a negative scale can be applied. This can be useful in mirroring the geometry (e.g., using a right hand mesh for a left hand). Mirroring the geometry will typically change the "winding" of the mesh elements. By convention, Drake looks at the ordering of the vertices that form mesh elements (triangles and tetrahedra) and derives the notion of "inside" and "outside" relative to that element. In order to preserve the input mesh's definition of "inside" and "outside", when the mesh gets mirrored Drake may perturb the ordering of the vertex indices. For example, a triangle originally referencing vertices [0 1 2], when mirrored may change to [2 1 0], so don't be surprised if you introspect the details of the loaded mesh and you see such a change. An analogous change can affect the vertex ordering of tetrahedra in a volume mesh (i.e., a perturbation of the original vertex index list [0 1 2 3] to [2 1 0 3]).
#include <drake/geometry/shape_specification.h>
Public Member Functions | |
| Mesh (const std::filesystem::path &filename, double scale=1.0) | |
| Constructs a mesh shape specification from the mesh file located at the given file path. More... | |
| Mesh (const std::filesystem::path &filename, const Vector3< double > &scale3) | |
| Mesh-file variant that allows for specification of non-uniform scale. More... | |
| Mesh (InMemoryMesh mesh_data, double scale=1.0) | |
| Constructs a mesh shape specification from the contents of a Drake-supported mesh file type. More... | |
| Mesh (InMemoryMesh mesh_data, const Vector3< double > &scale3) | |
| Mesh-contents variant that allows for specification of non-uniform scale. More... | |
| Mesh (MeshSource source, double scale=1.0) | |
Constructs a mesh shape specification from the given source. More... | |
| Mesh (MeshSource source, const Vector3< double > &scale3) | |
| Mesh-source variant that allows for specification of non-uniform scale. More... | |
| ~Mesh () final | |
| const MeshSource & | source () const |
| Returns the source for this specification's mesh data. More... | |
| const std::string & | extension () const |
| Returns the extension of the mesh type – all lower case and including the dot. More... | |
| double | scale () const |
| Returns a single scale representing the uniform scale factor. More... | |
| const Vector3< double > & | scale3 () const |
| Returns general scale factors for this mesh. More... | |
| const PolygonSurfaceMesh< double > & | GetConvexHull () const |
| Reports the convex hull of the named mesh. More... | |
Implements CopyConstructible, CopyAssignable, MoveConstructible, MoveAssignable | |
| Mesh (const Mesh &)=default | |
| Mesh & | operator= (const Mesh &)=default |
| Mesh (Mesh &&)=default | |
| Mesh & | operator= (Mesh &&)=default |
 Public Member Functions inherited from Shape | |
| virtual | ~Shape () |
| void | Reify (ShapeReifier *reifier, void *user_data=nullptr) const |
Causes this description to be reified in the given reifier. More... | |
| std::unique_ptr< Shape > | Clone () const |
| Creates a unique copy of this shape. More... | |
| std::string_view | type_name () const |
| Returns the (unqualified) type name of this Shape, e.g., "Box". More... | |
| std::string | to_string () const |
| Returns a string representation of this shape. More... | |
| template<typename ReturnType = void, typename Visitor > | |
| decltype(auto) | Visit (Visitor &&visitor) const |
Calls the given visitor function with *this as the sole argument, but with *this downcast to be the shape's concrete subclass. More... | |
Additional Inherited Members | |
| Protected Types inherited from Shape | |
| using | VariantShapeConstPtr = std::variant< const Box *, const Capsule *, const Convex *, const Cylinder *, const Ellipsoid *, const HalfSpace *, const Mesh *, const MeshcatCone *, const Sphere * > |
| (Internal use only) All concrete subclasses, as const pointers. More... | |
| Protected Member Functions inherited from Shape | |
| Shape () | |
| (Internal use only) Constructor for use by derived classes. More... | |
| Shape (const Shape &)=default | |
| (Internal use only) For derived classes. More... | |
| Shape & | operator= (const Shape &)=default |
| (Internal use only) For derived classes. More... | |
| Shape (Shape &&)=default | |
| (Internal use only) For derived classes. More... | |
| Shape & | operator= (Shape &&)=default |
| (Internal use only) For derived classes. More... | |
Constructs a mesh shape specification from the mesh file located at the given file path.
Optionally uniformly scaled by the given scale factor.
The mesh file referenced can be an .obj, a volume mesh in a .vtk, or a .gltf file. However, not all file formats are appropriate for all roles. (E.g., a tetrahedral .vtk file should not be assigned a perception role.)
| filename | The file name; if it is not absolute, it will be interpreted relative to the current working directory. |
| scale | An optional scale to coordinates. |
| std::exception | if |scale| < 1e-8. Note that a negative scale is considered valid. We want to preclude scales near zero but recognise that scale is a convenience tool for "tweaking" models. 8 orders of magnitude should be plenty without considering revisiting the model itself. |
Mesh-file variant that allows for specification of non-uniform scale.
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explicit |
Constructs a mesh shape specification from the contents of a Drake-supported mesh file type.
The mesh is defined by the contents of a mesh file format supported by Drake. Those contents are passed in as mesh_data. The mesh data should include the main mesh file's contents as well as any supporting file contents as needed. See InMemoryMesh.
| mesh_data | The in-memory file contents that define the mesh data for this shape. |
| scale | An optional scale to coordinates. |
| Mesh | ( | InMemoryMesh | mesh_data, |
| const Vector3< double > & | scale3 | ||
| ) |
Mesh-contents variant that allows for specification of non-uniform scale.
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explicit |
Constructs a mesh shape specification from the given source.
| source | The source for the mesh data. |
| scale | An optional scale to coordinates. |
| Mesh | ( | MeshSource | source, |
| const Vector3< double > & | scale3 | ||
| ) |
Mesh-source variant that allows for specification of non-uniform scale.
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final |
| const std::string& extension | ( | ) | const |
Returns the extension of the mesh type – all lower case and including the dot.
If this is constructed from a file path, the extension is extracted from the path. I.e., /foo/bar/mesh.obj and /foo/bar/mesh.OBJ would both report the ".obj" extension. The "extension" portion of the filename is defined as in std::filesystem::path::extension().
If this is constructed using in-memory file contents, it is the extension of the MemoryFile passed to the constructor.
| const PolygonSurfaceMesh<double>& GetConvexHull | ( | ) | const |
Reports the convex hull of the named mesh.
Note: the convex hull is computed on demand on the first invocation. All subsequent invocations should have an O(1) cost.
| if | the referenced mesh data cannot be read or is degenerate (insufficient number of vertices, co-linear or coincident vertices, etc.) All of the vertices lying on a plane is not considered degenerate. |
| double scale | ( | ) | const |
Returns a single scale representing the uniform scale factor.
| if | the scale is not uniform in all directions. |
| const MeshSource& source | ( | ) | const |
Returns the source for this specification's mesh data.