A detailed demonstration of the ray tracer is available on Medium.

The final ray-traced image

Soft shadows via distribution ray tracing of shadow rays on area lights

Stencil mode. Edge-detection is used to draw outlines around 3D shapes.

Voxel mode. Here, geometric primitives are approximated with little cubes.

Stencil mode and depth of field

Voxel mode + Depth of Field

The first scene I designed for the ray tracer

Unvoxelated version, with depth-of-field enabled on the right.