Outlines are a fundamental part of visual storytelling, from classic comic strips to modern video games. But rendering them in 3D graphics isn’t as simple as drawing a line—it requires smart techniques and clever tricks to get them looking just right.
In this deep dive, we explore the key methods used to generate outlines in 3D rendering, including:
- ✅ Rim shaders for smooth contour detection
- ✅ Vertex extrusion for simple outlines of round surfaces
- ✅ Image-based edge detection using blurs, Sobel filters, and more
- ✅ The powerful jump-fill algorithm for thick, high-quality outlines
Along the way, we’ll break down the strengths and weaknesses of each approach, explain how they work under the hood, and share practical tips for implementing them in your own projects. Whether you’re making a stylized indie game or refining a high-end shader, these techniques will help you master the art of outlines.
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Example code
You can find the code for this video here: https://github.com/Gamelogic-Code/Out…
Additional reading
- 📝 5 ways to draw an outline (2021) by Alexander Ameye : https://ameye.dev/notes/rendering-out…
- 📝 Outline Shader by Roystan: https://roystan.net/articles/outline-…
- 📝 [Study Note] Outline Shader in Unity (2021) by “baibaiya”: / study-note-outline-shader-in-unity
- 📝 The Quest for Very Wide Outlines (2020) by Ben Golus (this describes how to use anti-aliasing in the jump fill algorithm for smoother outlines): / the-quest-for-very-wide-outlines