# shz_vec4_refract

Source: https://sh4zam.com/api/vector/shz_vec4_refract/

> Refracts the given 4D incidence vector against a surface with the given normal using the given refraction index ratio, eta

```c
SHZ_INLINE shz_vec4_t shz_vec4_refract(shz_vec4_t incidence, shz_vec4_t normal, float eta) SHZ_NOEXCEPT;
```

Refracts the given 4D `incidence` vector against a surface with the given `normal` using the given refraction index ratio, `eta`.

## Parameters

| Name | Type | Description |
| --- | --- | --- |
| `incidence` | `shz_vec4_t` |  |
| `normal` | `shz_vec4_t` |  |
| `eta` | `float` |  |

## Returns

`shz_vec4_t`

## Availability

- **C++ equivalent:** [`shz::vec4::refract`](https://sh4zam.com/api/cpp/vec4/#refract)
- **Type-generic form:** [`shz_vec_refract()`](https://sh4zam.com/api/vector/shz_vec_refract/)
- **Back-ends:** SH4: shared C implementation · SW: portable C · SPU: shared C implementation
- **Defined in:** [`sh4zam/shz_vector.h:544`](https://github.com/gyrovorbis/sh4zam/blob/ba1e30c88d49df0311870b229e1dd860ef26c477/include/sh4zam/shz_vector.h#L544)
- **Module:** [Vector](https://sh4zam.com/api/vector/), section "Binary Operations"