Introduction

🤔 N-Gons are one of the most debated topics in 3D modeling! They’re usually associated with smoothing artifacts and ‘bad’ topology.

Figure 1. N-gons where cylinders intersect.

Figure 1. N-gons where cylinders intersect.

Figure 2. Zebra matcap showing smoothing artifacts around the intersection area.

Figure 2. Zebra matcap showing smoothing artifacts around the intersection area.

Attempt to Fix N-Gons

😤 When n-gons are present, the initial response is to convert them to quads. It’s common to manually edit and reroute topology to eliminate n-gons. In this case, despite having only quads, shading artifacts are still present.

Figure 3. Eliminating n-gons using rerouting tricks.

Figure 3. Eliminating n-gons using rerouting tricks.

Figure 4. Same mesh in Fig 3 showing shading artifacts.

Figure 4. Same mesh in Fig 3 showing shading artifacts.

Figure 5. https://topologyguides.com/

Figure 5. https://topologyguides.com/

⁉️ So how do we have clean shading? First, we should change our perspective. Instead of focusing on eliminating them, we should question why we have n-gons in the first place.

Problem Is the Base Mesh

💡 If we zoom out and see the bigger picture, we can see that underlying shapes don’t have a consistent geometry density. The cylinder is denser than the pipe. Edges don’t align and they have nowhere to go, which produces smoothing artifacts and n-gons. To solve this, we should go back to the block out.

Figure 6. Showing the process of how we got here in the first place.

Figure 6. Showing the process of how we got here in the first place.

Figure 7. Base mesh. Highlighted edges have nowhere to flow.

Figure 7. Base mesh. Highlighted edges have nowhere to flow.

  1. First, ensure that the base shape, the pipe, has sufficient geometry to support different shapes and details.
  2. Then, adjust segments of the cylinder for consistent geometry throughout the model. This consistent geometry will ensure continuous edge flow across different meshes.

Figure 8. Adjusting geometry density to achieve consistency. (Sorry, can’t animate curves in Blender 😭)

Figure 8. Adjusting geometry density to achieve consistency. (Sorry, can’t animate curves in Blender 😭)