Mesh

A Mesh is a data structure that represents a triangulated surface.

A structure of a mesh includes:

• vertices (red) - triangle points, each defined by a 3D coordinate;
• faces (green) - triangles formed from available vertices, defined by vertex indices (for example f1 is defined by vertices v1, v2, v5);
• halfedges (blue) - directed edges, each defined by a vertex it points to and a face to which it belongs (for example he1 is defined by vertex v1 and face f1). In other words, when some property is assigned to a halfedge, it’s assigned to a corresponding vertex of a corresponding face.

Each triangle is expected to have a counterclockwise winding order. If a mesh that doesn’t satisfy this condition is loaded, the program will either try to re-orient the triangles or - if that’s not possible - it will duplicate them.

An optional list of properties includes:

• face normals - normal assigned to each face;
• face labels - label assigned to each face;
• vertex normals - normal assigned to each vertex;
• vertex colors - color assigned to each vertex;
• vertex texture coordinates - coordinates assigned to each vertex for a look-up in a 2D texture map attached to the mesh;
• vertex labels - label assigned to each vertex;
• halfedge normals - normal assigned to each halfedge;
• halfedge colors - color assigned to each halfedge;
• halfedge texture coordinates - coordinates assigned to each halfedge for a look-up in a 2D texture map attached to the mesh.

See tutorial video on how to work with meshes here

Annotation

Mesh annotation belongs to a special data annotation. When a mesh is created/loaded, its annotation will show up in the 3D view. Besides the algorithms, there are several ways to manipulate the mesh data or change its annotation visualization:

• Context menu
• Mesh Display Options
• Mesh Data Controller

Context menu

A right-click on the mesh annotation in the annotation widget opens a context menu containing different algorithms, visualization options and other actions applicable to meshes.

• Algorithms. Refer to this page for the documentation of some available algorithms.

• Visualization options. The list of options available specifically for the mesh annotations includes:

  • Change Line Width. When MPR views are open and their planes intersect a mesh, the intersection contours will be visualized in these views. The line width controls the thickness of these contours.

  • Show Cross-Section. Fills in the intersection contour in the MPR views.

  • Change Cross-Section Color. Allows to change the fill color of the intersection contour in the MPR views.

  • Draw Normals. When checked, mesh normals will be visualized.

  • Lighting Mode (Enable Front, Enable Back). Controls the lighting for front and back side of the faces.

  • Render Mode:

    • Surface. Only the surface of the mesh is visualized.
    • Wireframe. Only the triangle edges are visualized.
    • Surface + Wireframe. Both, surface and triangle edges, are rendered.

  • Change Wireframe Color. Changes the color of the triangle edges in Wireframe and Surface + Wireframe modes.

  • Material Mode. Possible available options are:

    • Uniform. Surface of the mesh is rendered with a uniform color
    • Color. Surface of the mesh is rendered using vertex or halfedge colors
    • Texture`. Surface of the mesh is rendered using an attached texture map
    • Shader. Surface of the mesh is rendered using an attached custom shader
    • Face Label. Surface of the mesh is rendered using colors of assigned face labels
    • Vertex Label. Surface of the mesh is rendered using colors of assigned vertex labels

  • Change Color. This parameter changes color of the mesh in a Uniform material mode and color of the intersection contours in MPR views.

• Other actions:

  • Move to Center. Applies a transformation matrix to the mesh such that it is afterwards centered in the world coordinate system.
  • Burn-in Transformation. Transforms all the vertices and normals of the mesh.
  • Reset Transformation. Sets the transformation matrix to identity.
  • Use Local Coordinates. Specifies to use mesh local coordinates when initializing Mesh Manipulator (see below).

  Refer to transformation dialog dialog to view or modify mesh transformation matrix (note: convention of the mesh matrix is from local to world).

Mesh Display Options

Mesh Display Options is a data component that allows configuring advanced rendering options. To open, right-click on mesh in the annotation widget, select Inspect Properties -> MeshDisplayOptions.

Mesh Data Controller

Depending on the current setting this controller can be either detached, or located in a toolbar, a primary or a secondary dock.

Available options can be split into following categories:

• Visualization:

  • Render Mode: Surface, Wireframe or Surface + Wireframe (described earlier).
  • Material Mode: Uniform, Color, Texture, Shader, Face Label, Vertex Label (described earlier).
  • Lighting: on or off for both, front and back side of a mesh.
  • Triangle Normals: if on, mesh surface will be rendered using face normals instead of vertex normals.

• Mesh Manipulator

  • Translate: adds a manipulator for translating the mesh (this changes transformation matrix of the mesh).
  • Rotate: adds a manipulator for rotating the mesh (this changes transformation matrix of the mesh).

• Mesh Info Overlay (View Mesh Info). Shows selected information as a text overlay in the left corner of the 3D View. Available options are:

  • Triangle info. Displays all available information that a particular triangle has: face index, face normal, face label, 3 vertex indices, 3 vertex positions, 3 vertex normals, 3 vertex colors, 3 vertex texture coordinates, 3 vertex labels, 3 halfedge normals, 3 halfedge colors, 3 halfedge texture coordinates.
  • Vertex info. Displays all available information that a particular vertex has: index, position, normal, color, label.
  • Edge info. Displays all available information that a particular edge has: face index, 2 vertex indices, 2 vertex positions, 2 halfedge normals, 2 halfedge colors, 2 halfedge texture coordinates.
  • Show holes. Displays a contour of the boundary faces.
  • Show non-manifold vertices. Displays non-manifold vertices. These are vertices that are either known to have duplicates, or if more than one gap exists, i.e. more than one outgoing boundary halfedge.