Unity Spherical Harmonics Tools

Overview

In this project the are two tools: the first one takes an input cubemap and project into the spherical harmonic basis and print the first three bands (9 coefficients). It's possible to compute this projection with 3 different techniques:

• On the CPU with uniform sampling, which means reading all the texels of the cubemap.
• On the CPU with Monte Carlo sampling, which means less texture readings, more rapid but with an approximated result.
• On the GPU with Monte Carlo sampling, with a result similar to the CPU one but faster.
• On the GPU with uniform sampling, using a Compute Shader, this gives the accuracy of CPU uniform sampling with maximum speed. I Recommend using this.

Once the result is computed you can see it and toggle the original version and the projected one.

The Geometry Factor describes the visibility from the vertex (so 0 if the vertex is occluded or 1 if the vertex can see direclty the environment from direction v) multiplied with che cosine of the vertex normal with the direction v.

At the momenty Unity doesn't support custom vertex attributes so i had to put the 9 coefficients in the existing ones, organizing them in this way: first 4 coefficients in the vertex color rgba, the next 2 in the uv2, the next 2 in the uv3 and the last one in the x component of uv4. It's a temporary solution and i hope to find a better workaround.