Latitude/longitude tessellation rather than an icosphere: it is the layout
whose uv is a plain rectangle, which is what makes an equirectangular texture
— the one people actually have for spheres — map without a seam chart.
The cost is the pole singularity, where a row of quads degenerates into
zero-area triangles; those rasterize to nothing and the surrounding normals
stay exact, because they are the analytic position / radius.
Uv is u = θ / 2π (0 at +X, advancing with the winding) and v = 0 at the
south pole, 1 at the north — so v grows with +Y, matching §7a.
A UV sphere centred on the origin (§53 "sphere").
Latitude/longitude tessellation rather than an icosphere: it is the layout whose uv is a plain rectangle, which is what makes an equirectangular texture — the one people actually have for spheres — map without a seam chart. The cost is the pole singularity, where a row of quads degenerates into zero-area triangles; those rasterize to nothing and the surrounding normals stay exact, because they are the analytic
position / radius.Uv is
u = θ / 2π(0 at +X, advancing with the winding) andv = 0at the south pole,1at the north — sovgrows with+Y, matching §7a.