GLSL for POPs in TouchDesigner: Lesson 7 (GLSL Advanced POP - Voronoi Fracture pt. 2)

You made it!! In this final lesson, we take the Voronoi region data from Part 1 and extract the actual crack lines where two Voronoi cells meet. This is where the effect comes alive. Using GLSL, we detect exact boundary crossings on triangle edges and reposition prebuilt line segments entirely on the GPU — no SOPs, no CPU passes, no extra geometry creation.

You’ll learn how to compute signed distance differences between sites, solve for f_dist = 0 along each mesh edge, and output perfectly precise Voronoi crack lines. This system is ideal for stylized cracks, procedural erosion, organic cell borders, simulation-driven splitting effects, and any algorithmic linework on arbitrary meshes.

📌 Key Topics Covered:✅ Using f_dist to find where Voronoi boundaries cut across triangle edges✅ Computing exact boundary intersections with linear interpolation (GPU-side)✅ Handling 2-point crack edges and 3-point junctions✅ Repositioning pre-allocated line geometry for efficient GPU rendering✅ Coloring, styling, and organizing crack outputs✅ Strategies for visual debugging and numerical stability

🎨 Exercises & Challenges:🛠️ Add anti-aliased crack rendering with width and softness controls🛠️ Drive site positions with audio or sensor data for reactive cracks🛠️ Generate multiple line segments per triangle to visualize full junction graphs🛠️ Blend cracks with shaders for stylized erosion, fracture, or organic growth

🔗 Further Learning:
TouchDesigner Docs → https://docs.derivative.ca
Writing GLSL POPs → https://derivative.ca/UserGuide/Exper...
GLSL in TouchDesigner (Courses & Files) →   / water__shed  

Find me online:
🔹 Project Files & Patreon:   / water__shed  
🔹 Portfolio: https://www.lakeheckaman.com
🔹 Instagram:   / lake_heckaman  

00:00 - Start
00:02 - Intro
01:59 - GLSL Adv POP Extra Output Setup Example
05:59 - Voronoi Lines