Mesh Optimization and Watertight Export

Foxel includes two important geometry-related export settings:

• Optimize
• Watertight

Both affect the exported mesh, but they solve different problems.

Optimize is mainly about efficiency.

Watertight is mainly about closed geometry.

Why This Matters

These two settings both affect mesh geometry, but they are not interchangeable.

If you treat them as the same kind of setting, export behavior becomes harder to predict.

A useful way to separate them is:

• Optimize makes the exported mesh lighter.
• Watertight attempts to make the exported mesh closed.

Optimize

Optimize optimizes the exported mesh for reduced file size and better performance.

Use it when the exported result should be lighter and more efficient for downstream use.

This is especially useful for:

• Game engines
• Real-time viewers
• Asset libraries
• Larger production workflows

What Optimize Is For

Optimize is mainly about efficiency.

It can help reduce unnecessary mesh data and make exported assets more practical to use outside Foxel.

Use it when:

• File size matters.
• Runtime performance matters.
• The asset will be used in a real-time environment.
• Many exported assets need to be managed together.

Watertight

Watertight attempts to generate closed mesh geometry without holes or gaps.

Use it when the exported result should behave more like a closed solid mesh instead of an open surface result.

What Watertight Is For

Watertight is mainly about geometric closure.

It is useful when the target workflow expects closed meshes, or when open areas in the exported geometry would cause problems.

Use it when:

• The exported mesh should behave like a solid object.
• Holes or gaps would cause issues in the target application.
• The mesh will be processed further after export.
• Closed geometry matters more than producing the lightest possible output.

Why They Are Different

A simple way to think about the difference is:

• Optimize improves efficiency.
• Watertight improves closure.

So:

• Optimize is not mainly about closing holes.
• Watertight is not mainly about reducing file size.

That is why both settings can matter in the same export workflow.

For example, you may want a mesh that is both lighter and more closed, depending on where the exported asset will be used.

When To Care Most

These settings matter most when:

• The mesh is going into a game engine or production pipeline.
• File size and runtime efficiency matter.
• The exported geometry should be cleaner and more predictable.
• Closed geometry is important for the downstream use case.
• The exported asset will be reused many times.

What To Remember

• Optimize reduces file size and can improve performance.
• Watertight attempts to generate closed mesh geometry.
• They solve different problems.
• Optimize is about efficiency.
• Watertight is about closure.
• Both are important geometry-related export settings.