This Unity Tool Lets You Paint Hidden Outlines

Alexander Ameye, who recently showcased a custom renderer for creating very hard shadows, has shared another custom-made Unity project still in development. This new tool allows to paint a hidden outline map, which is then used by the outline shader.

Instead of relying on depth and normals for drawing outlines, the developer uses a custom section buffer. This buffer is not visible to the player but serves an internal purpose, enabling the drawing of outlines independently of the scene geometry.

The key advantage of this approach is that it gives full control over the placement of lines, something that's difficult to achieve with traditional depth/normals-based outlines. The tool allows the painting of a very low-resolution "section", which is then converted into a signed distance field, ensuring that the final section map remains crisp and clear when sampled.

As the developer explained, the texture he paints is UV-dependent, meaning the outlines don't rely on specific edge and face orientations but still require UVs. Seams in the UVs can cause issues, with outlines appearing strange at those points. Alexander is working on a solution to make the system completely independent of both geometry and UVs but hasn't found one yet.

You can see the original post for details here and check out the developer's outlining toolkit available on Unity Asset Store. Alexander describes this pack as the result of years of experimentation with outline rendering in Unity, offering multiple techniques for achieving any type of outline effect you need:

Learn more about Alexander Ameye's projects here and join our 80 Level Talent platform and our new Discord server, follow us on Instagram, Twitter, LinkedIn, Telegram, TikTok, and Threads, where we share breakdowns, the latest news, awesome artworks, and more.