Using the SurfaceTool

The SurfaceTool also provides some useful helper functions like and generate_normals().

Attributes are added before each vertex is added:

GDScript

When finished generating your geometry with the SurfaceTool call commit() to finish generating the mesh. If an is passed to commit() then it appends a new surface to the end of the ArrayMesh. While if nothing is passed in, commit() returns an ArrayMesh.

st.commit(mesh)
# Or:
var mesh = st.commit()

Code creates a triangle with indices

GDScript

You can optionally add an index array, either by calling add_index() and adding vertices to the index array or by calling index() which shrinks the vertex array to remove duplicate vertices.

GDScript

# Creates a quad from four corner vertices.
# Add_index does not need to be called before add_vertex.
st.add_index(1)
st.add_index(2)
st.add_index(1)
st.add_index(3)
# Alternatively:
st.index()

GDScript

If you don’t add custom normals yourself, you can add them using generate_normals(), which should be called after generating geometry and before committing the mesh using or commit_to_arrays(). Calling generate_normals(true) will flip the resulting normals. As a side note, generate_normals() only works if the primitive type is set to Mesh.PRIMITIVE_TRIANGLES.

If you don’t add custom tangents, they can be added with generate_tangents(), but it requires that each vertex have UVs and normals set already.

GDScript

st.generate_normals()
st.generate_tangents()