---
title: "Rasterizer State"
date: 2021-01-27T15:30:01-08:00
weight: 6
---

Rasterization is, essentially, the process of converting 3D vertex information into pixels on a surface. There are many different ways that we may wish to control rasterization.

Note that I am mostly going to discuss triangles here. Many of these options will be ignored unless you are using triangle primitives, for soon to be obvious reasons.

`FrontFace` specifies which triangles we will designate as "front-facing", using what we call "winding order". If we use `FrontFace.CounterClockwise`, then triangles listed in counter-clockwise order will be designated as front faces. Likewise, if we use `FrontFace.Clockwise`, clockwise triangles will be designated as front faces. Which order you choose depends on the format of your vertex data.

Why is this important? The answer is "primitive culling". A lot of the time we have no need to render triangles that are facing away from the camera, so we can save a lot of processing time by not rasterizing those triangles.

`CullMode` has four options: `None`, `Front`, `Back`, and `FrontAndBack`.

`FillMode` tells the rasterizer how to fill in the triangles. `Fill` completely fills the triangle. `Line` only renders the edges of the face. `Point` only renders the input points. `Line` mode is also referred to as "wireframe rendering" which is useful for debugging.

`LineWidth` describes lines in terms of pixel width. Maximum line width above 1f is hardware-specific so be careful with this one.

Finally, the rasterizer can alter depth values by adding a constant factor or biasing them based on slope. This can sometimes be useful for shadow mapping. Most of the time you won't be needing this and you can just set `DepthBiasEnable` to false.

```cs
var myRasterizerState = new RasterizerState
{
    FrontFace = FrontFace.Clockwise,
    CullMode = CullMode.Back,
    FillMode = FillMode.Fill,
    LineWidth = 1f,
    DepthBiasEnable = false
};
```