While working with some 3D model, converting it from one format to another, I noticed something strange. The Positions and Normals arrays contained a lot duplicate values, while the Indices array - contained common data for Positions and Normals, for example, for describing Positions and Normals of two triangles, the Indices array looked like this: “0 2 4 0 1 3”. I was so much confused about this, I couldn’t understand what is going on. Why the Normals and Positions arrays contain so many duplicate coordinates? Why the Indices array is half of the size that it’s supposed to be? That looked like a hack or some kind of protection or encryption, which is not straight - forward to understand.
Could someone correct me if I’m wrong: the Positions and Normals arrays are not supposed to have duplicates, the whole point of using Indices - is to shrink, to minify the arrays with coordinates, to get rind of duplicate values, that what the Indices are used for. The indices array - is supposed to have at least 2 times more values than the amount of triangles - one set for Positions and another set for Normals. Am I right?