ABSTRACT
As a designer of virtual worlds you will probably spend a great deal of time thinking about meshes. Meshes comprise a significant portion of a virtual environment, and their appearance and physical behavior in response to an avatar’s actions is crucial to creating an immersive sense of space for the visitor. Now, please understand that a highly detailed, almost realistic version of some real-world scene that you built for your game-based virtual environment may go mostly unnoticed by your visitor. This is not a bad thing; in fact, the ability to create an environment that is easily understandable and supports an instinctual interaction for the visitor is the hallmark of a good designer. A familiar environment clears the way for good communication too, because it sets up a common frame of reference for all the visitors. Of course, you may want to design an alien-fantasy environment that comes directly from your imagination and has elements not included in our typical real-world environment. If you wind the constructs of the alien-fantasy world around your core awareness of real-world design, so that the visitor is at once experiencing the alien and familiar, then your overall design will become deeply immersive. They will be thinking, “So this is how the aliens create a meeting space. I understand its function, but how strangely interesting and different it is!” This is what meshes are; they are the fabric of your imagination. But, what is a mesh actually? It is a data set that contains spatial and visual information about the elements within it. The simplest element of a mesh is a polygon, or many-sided plane. Every polygon in your mesh is subdivided into triangles, which, as you know from basic geometry, contain the smallest number of vertices necessary to determine a plane in space or a face on a polygonal mesh. The information about where these vertices are located in 3D space, data about the kinds of materials and shaders on the faces (triangles) of each part of the mesh, and how each face is lit or shaded by a light source in the scene are all part of the mesh data set that is passed on to the rendering engine in your computer. In Figure 10.1 is a diagram showing the structure of a polygonal mesh (the classic teapot) and how all of its parts work together to create a mesh model in your virtual world. Notice how the triangles form the basic elements of every mesh, no matter how complex. In the lower half of Figure 10.1, note how the Texture (diffuse) graphic of a mesh can be created from a process called baking, which calculates the lighting and reflections on the entire surface and renders it out onto a flat graphic, which is also known as a UV map (UV coordinates are the XY equivalents on graphics, maps, and textures in a 3D modeler). This baked map will be wrapped back onto the mesh once it is imported into your virtual environment. This is the best way to create a realistic look with the least amount of real-time processing,
A Mesh is a Database
A baked texture shows the light and shadow on its surface and can be re-wrapped around the mesh geometry in the virtual environment.
