   Spherical Harmonics question
  I don´t know much about spherical harmonics, but almost everything i´ve seen done with them stores them per-vertex. Why is it not common to store them per-pixel, in a lightmap? I assume that for good quality you would need at least two lighmaps to store enough coefficients, increasing memory cost...but it would be possible to use them with normal mapping and obtain better quality.So, why are them stored per vertex?   
  They are not always stored per-vertex. Check recent and previous papers from HALO developers (available on their website), they store SH per-texel in "lightmaps".   ;  Usually people use 9 SH coefficients (27 floats for RGB), or 4 for low-quality (12 floats for RGB). That's a lot of data per-pixel (3-7 textures layers for your lightmaps).Valve's famous "Half-life 2 basis" uses 3 coefficents (9 floats for RGB), which is 3 texture layers.I read an interesting paper recently that presents the "H-basis", which is like SH, but restricted to a hemisphere instead of a full sphere. They show examples for 4 and 6 coefficients (3-5 texture layers).I guess per-vertex could be popular because this is a lot of storage ;)It really depends on how tesselated your scene is, and how much high-frequency detail (e.g. shadow borders) are present in the lighting, as to wheather lightmaps or per-vertex is more appropriate, I guess.   ;  Oh, i see, so it is not that trivial to have per-pixel sh, a lot of storage is required. I read trough some Bungie papers and the way they do it in halo3, and also read some papers about different basis (wavelets and hbasis). I think for now the simplest way to go for me is the basis Valve used in HalfLife.Thanks to both of you!   