TODO
- Transformations
- Matrix
- Spheres
- BxDFs
- Primitives
- Area lights
- Better sampling for spheres and triangles
- Emissive textures
- Handled flipped normals correctly
- Handle rounding error properly
- Disc shape
- Textures
- Film
- Thin lens camera
- Samplers
- Fix cosine_sample_hemisphere assert failing with SobolSampler
- Spectrum