![]() Additionally, very high resolution meshes are less subject to issues that would require smoothing groups, as their polygons are so small as to make the need irrelevant. As an alternative to providing surfaces/smoothing groups, a mesh may contain other data for calculating the same data, such as a splitting angle (polygons with normals above this threshold are either automatically treated as separate smoothing groups or some technique such as splitting or chamfering is automatically applied to the edge between them). Thus, some way of determining where to cease smoothing is needed to group smooth parts of a mesh, just as polygons group 3-sided faces. Rendered as a single, Phong-shaded surface, the crease vertices would have incorrect normals. For smooth shading of the sides, all surface normals must point horizontally away from the center, while the normals of the caps must point straight up and down. ![]() Consider a cylinder with caps, such as a soda can. surfaces More often called smoothing groups, are useful, but not required to group smooth regions. Mathematically a polygonal mesh may be considered an unstructured grid, or undirected graph, with additional properties of geometry, shape and topology. However, most rendering hardware supports only 3- or 4-sided faces, so polygons are represented as multiple faces. In systems that support multi-sided faces, polygons and faces are equivalent. face A closed set of edges, in which a triangle face has three edges, and a quad face has four edges. Vertex A position (usually in 3D space) along with other information such as color, normal vector and texture coordinates. However, many renderers either support quads and higher-sided polygons, or are able to convert polygons to triangles on the fly, making it unnecessary to store a mesh in a triangulated form. A renderer may support only 3-sided faces, so polygons must be constructed of many of these, as shown above. In many applications, only vertices, edges and either faces or polygons are stored. These include vertices, edges, faces, polygons and surfaces. Objects created with polygon meshes must store different types of elements. Several methods exist for mesh generation, including the marching cubes algorithm. Volumetric meshes are distinct from polygon meshes in that they explicitly represent both the surface and volume of a structure, while polygon meshes only explicitly represent the surface (the volume is implicit). If the mesh's edges are rendered instead of the faces, then the model becomes a wireframe model. Algorithms also exist for ray tracing, collision detection, and rigid-body dynamics with polygon meshes. The variety of operations performed on meshes may include: Boolean logic ( Constructive solid geometry), smoothing, simplification, and many others. Different representations of polygon meshes are used for different applications and goals. The study of polygon meshes is a large sub-field of computer graphics (specifically 3D computer graphics) and geometric modeling. The faces usually consist of triangles ( triangle mesh), quadrilaterals (quads), or other simple convex polygons ( n-gons), since this simplifies rendering, but may also be more generally composed of concave polygons, or even polygons with holes. In 3D computer graphics and solid modeling, a polygon mesh is a collection of vertices, edges and faces that defines the shape of a polyhedral object. Example of a low poly triangle mesh representing a dolphin
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