![]() The vertices v0, v1, v2 and v3 are making up the first face, while connecting vertices v0, v3, v4 and v5 in this order gives the second face. Finally for each face, we need to know how the vertices are connected to other to create the faces, their indexes in the vertex array list, and the order in which they should be connected. The size of this array is equal to the number of faces in the mesh (2). The first and the second face from our mesh have 4 vertices therefore this array would contain the following data. We also need an array of integers which indicates how many vertices each face is made of (the face index array). The other information we need is the total number of faces the mesh contains. In this example we would have 6 vertices v0, v1, v2, v3, v4 and v5. ![]() Let's consider an example of two quads sharing a common edge (figure 1). The first thing we expect to define a mesh is therefore a list of vertices. Mesh Definitionįigure 1: a simple mesh with 2 faces and 6 vertices.Ī polygon mesh is made out of vertices which are connected to each other to form faces. The goal of this basic lesson is to learn how to define a polygon mesh in our program (chapter 2) and render this mesh using ray tracing (chapter 3). Polygon meshes are simple in principle but have they own set of problems: for instance how do we smooth a low poly mesh (a mesh that has a small number of polygons may appear blocky), or how do we efficiently encode the vertex connectivity data of a mesh? These techniques will be studied in the advanced section. We can also combine polygons together to create complex polyhedral objects. Three vertices define a triangle, and four define a quad. Therefore, the number of vertices making up a face has to be greater or equal to three. Two vertices connected to each other form an edge. A polygon or a face is a flat surface (it should be but if the vertices making up the face are not coplanar it won't be) which is defined by a set of vertices connected to each other to form a closed shape. These objects are made out of polygons which we also call faces. Polygon meshes are not used much in film (where a more sophisticated type of primitive, the subdivision surface is preferred) but they stay very popular in games and real time applications in general. Usually the simplest form of object we can find right after simple primitives such as spheres and triangles, are polygonal objects (which are also called polygon meshes). ![]() We learned how to render triangles in the previous lesson which leads us to the next step: rendering more complex objects. Want to report bugs, errors or send feedback? Write at We do this for free, please be kind. Source Code Keywords: ray-tracing, polygon mesh, tessellation, triangulation, triangle, barycentric coordinates, interpolation, normals, vertex attribute, texture coordinates.
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