BRDFEstimator: implement a GUI tool.
BRDFEstimator: implement a GUI tool.

GUI allows to compute irradiance SH coeffs and BRDF pre-convolved maps for any HDR cubemap, and BRDF lookup table.


Former-commit-id: d765d3914b9ce45bdef42f373d64ceba485f271d
kosua20/GL_Template,kosua20/GL_Template