When creating a forest scene in iClone 8, you may notice characters running through grass, leaves, or rocks without proper collision. This usually depends on the asset format you are using.

1. Why Some Grass Has No Collision

For instance, Tthe Total Plants 2: Botanical World pack mainly uses iGrass format, which:

• Has no collision mesh
• Cannot be set as Static/Dynamic
• Cannot trim NavMesh directly
• Does not support physics interaction
• iGrass file cannot be exported as FBX

That’s why characters pass through it.

In contrast, the grass used in this demo: https://youtu.be/s2CHj5bxC2E?si=nfDUDedXyE5-jo0o&t=292

Apocalyptic London is iProp-based and supports Soft Cloth physics, allowing grass to react when characters walk through it.

2. Workaround for iGrass defection in Motion Director

If you must use iGrass:

1. Create a Box (Create → 3D Block → Box)
2. Scale it to overlap the grass area
3. Generate NavMesh
4. Trim the NavMesh with the box
5. Set the box to Dummy in Modify panel

This creates a hidden collision proxy.

Note:

For natural terrain movement, using Motion Director is recommended.

It automatically follows NavMesh and avoids obstacles, making it more efficient than manually creating a path.