Understand high quality line rendering

Rendering line topology via traditional hardware rasterization, for example to represent hair or fur, can easily suffer from image quality problems.

Use the High Quality Line Rendering override to draw line geometry with analytic anti-aliasing and transparent sorting.

An example of hardware lines.

An example of high quality lines.

The High Quality Line Renderer is a line segment software rasterizer designed for fast, high quality transparency and anti-aliasing.

Outlined below are the general steps of this raster algorithm.

The camera's view frustum is divided into many clusters. A single cluster is 8 pixels wide by 8 pixels high. The length is derived from the Cluster Count.
Each cluster computes a list of the visible line segments that intersect with it.
Clusters are processed in front-to-back order. For each cluster, the segment list is unpacked and sorted from front-to-back, and the Sorting Quality determines the maximum amount of segments sorted in a single cluster.
The sorted segment list is processed. For each segment pixel, HDRP computes the shading contribution, computes the analytically anti-aliased coverage mask, and blends the fragment behind the final tile result.
HDRP computes the average opacity of the tile. If the average opacity is greater than the Tile Opacity Threshold, the tile is complete. A threshold lower than 1.0 can greatly improve performance.
HDRP repeats steps 3 to 5 until all tiles have been processed.