Week 10 - Depth of Field

This week we learned about depth of field and had an in-class competition on friday.

Depth of field is an effect that causes objects that are out of focus to appear blurry.
Computer graphics uses the pinhole camera model which results in perfectly sharp images. The pinhole camera model only lets a single ray through. Real cameras use lenses with finite dimensions which is what causes depth of field.

Depth of Field Implementation:
- Use destination alpha channel to store per-pixel depth and blurriness information.
- Use fragment shader for post-processing
- Downsample and pre-blur the image
- Use variable size filter kernel to approximate circle of confusion
- Blend between original and pre-blurred image for better image quality
- Take measures to prevent "leaking" sharp foreground into blurry background
- We pass the camera distance of three planes to scene shaders
     - Focal plane: points on this plane are in focus
     - Near plane: Everything closer than this is fully blurred
     - Far plane: Everything beyond the far plane is fully blurred