# DoF (depth of field)

Depth of field simulates camera-lens behavior: objects at the **focus distance** are sharp,
everything else is progressively blurred (the cinematic "bokeh" look). DoF is a post-process
that operates on the HDR texture + depth buffer, before tone mapping.

> **Prerequisite**: like bloom, DoF reads the HDR texture (and the depth buffer for the
> focus/blur computation). Enable HDR together with it.

## Activation

DoF is opt-in through the builder. Without it, no DoF textures are allocated and the pipeline
cost is **zero**:

```rust
use wsg_lib::prelude::*;

let app = AppBuilder::new()
    .with_hdr(ToneMapper::Aces)
    .with_dof(DoFConfig::cinematic(4.0))  // sharp at 4.0 world units
    .build()
    .await?;
```

## `DoFConfig`

| Field | Type | Meaning |
|-------|------|---------|
| `focus_distance` | `f32` | World distance where the image is perfectly sharp |
| `aperture` | `f32` | Blur intensity (0.0–1.0, clamped). Scales the circle of confusion |
| `max_blur` | `f32` | Maximum blur radius in pixels (clamps the CoC) |

Presets:

```rust
DoFConfig::new(focus_distance, aperture, max_blur)  // custom
DoFConfig::cinematic(focus_distance)                // aperture 0.3, max blur 12 px (cutscenes)
DoFConfig::subtle(focus_distance)                   // aperture 0.1, max blur 8 px (gameplay)
```

## Runtime change

The `dof` example switches focus presets with the keys `1`–`4` (near / mid / far / infinity)
and follows the zoom:

```sh
cargo run -p wsg-lib --example dof
```

## Cost

- **Without DoF** (default): zero overhead — no textures, no pass.
- **With DoF**: 1 extra fullscreen pass + 2 intermediate textures (the bokeh buffer), before
  tone mapping.

## Limitations (MVP)

- A single focus distance per frame (no per-pixel focus / rack-focus over time).
- The blur is a fixed-radius Gaussian scaled by the circle of confusion.

## Links

- [User README](../README.md) · [Bloom](bloom.md) · [HDR & tone mapping](hdr.md) · [Examples](../examples.md)
- [Root README](../../../README.md)