Diffuse Object

For objects with only diffuse reflection on the surface, the reflection equation can be written as

$$\begin{aligned} L_o(\boldsymbol{\omega}_o)=\frac{\mathrm{base\_color}}{\pi} \int_{H^2}L_i(\boldsymbol{\omega}_i)V(\boldsymbol{\omega}_i)\mathbf{n}\cdot\boldsymbol{\omega}_i \:d\Omega_i, \end{aligned}$$

where $V(\boldsymbol{\omega}_i)$ is the visibility function. For simplicity, let’s assume $L_i(\boldsymbol{\omega}_i)$ is the radiance of environment light.