I know one good reason to prefer explicit location definition. Consider that you hold your geometry data in Vertex Array Objects. For a given object, you create a VAO in such way that the indices correspond to, for example: index 0: positions, index 1: normals, index 2: texcoords Now consider that you want to draw … Read more
(I’m taking a bit of a punt here, because your picture does not show exactly what I would expect from texturing a trapezoid, so perhaps something else is happening in your case – but the general problem is well known) Textures will not (by default) interpolate correctly across a trapezoid. When the shape is triangulated … Read more
Since you’ve tagged this with OpenGL ES 2.0, let me suggest an alternative approach for creating smooth spheres, and that’s to draw them as raytraced impostors. Rather than calculate the many vertices you’ll need to replicate a smooth sphere, you can take advantage of the fact that a sphere looks pretty much the same from … Read more