Files
godot-docs/tutorials/3d/procedural_geometry/surfacetool.rst
2025-07-30 16:23:22 +02:00

208 lines
6.3 KiB
ReStructuredText

.. _doc_surfacetool:
Using the SurfaceTool
=====================
The :ref:`SurfaceTool <class_surfacetool>` provides a useful interface for constructing geometry.
The interface is similar to the :ref:`ImmediateMesh <class_ImmediateMesh>` class. You
set each per-vertex attribute (e.g. normal, uv, color) and then when you add a vertex it
captures the attributes.
The SurfaceTool also provides some useful helper functions like ``index()`` and ``generate_normals()``.
Attributes are added before each vertex is added:
.. tabs::
.. code-tab:: gdscript GDScript
var st = SurfaceTool.new()
st.begin(Mesh.PRIMITIVE_TRIANGLES)
st.set_normal() # Overwritten by normal below.
st.set_normal() # Added to next vertex.
st.set_color() # Added to next vertex.
st.add_vertex() # Captures normal and color above.
st.set_normal() # Normal never added to a vertex.
.. code-tab:: csharp
st.SetNormal(); // Overwritten by normal below.
st.SetNormal(); // Added to next vertex.
st.SetColor(); // Added to next vertex.
st.AddVertex(); // Captures normal and color above.
st.SetNormal(); // Normal never added to a vertex.
When finished generating your geometry with the :ref:`SurfaceTool <class_surfacetool>`,
call ``commit()`` to finish generating the mesh. If an :ref:`ArrayMesh <class_ArrayMesh>` 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.
.. tabs::
.. code-tab:: gdscript GDScript
# Add surface to existing ArrayMesh.
st.commit(mesh)
# -- Or Alternatively --
# Create new ArrayMesh.
var mesh = st.commit()
.. code-tab:: csharp
st.Commit(mesh);
// Or:
var mesh = st.Commit();
The code below creates a triangle without indices.
.. tabs::
.. code-tab:: gdscript GDScript
var st = SurfaceTool.new()
st.begin(Mesh.PRIMITIVE_TRIANGLES)
# Prepare attributes for add_vertex.
st.set_normal(Vector3(0, 0, 1))
st.set_uv(Vector2(0, 0))
# Call last for each vertex, adds the above attributes.
st.add_vertex(Vector3(-1, -1, 0))
st.set_normal(Vector3(0, 0, 1))
st.set_uv(Vector2(0, 1))
st.add_vertex(Vector3(-1, 1, 0))
st.set_normal(Vector3(0, 0, 1))
st.set_uv(Vector2(1, 1))
st.add_vertex(Vector3(1, 1, 0))
# Commit to a mesh.
var mesh = st.commit()
.. code-tab:: csharp
var st = new SurfaceTool();
st.Begin(Mesh.PrimitiveType.Triangles);
// Prepare attributes for AddVertex.
st.SetNormal(new Vector3(0, 0, 1));
st.SetUV(new Vector2(0, 0));
// Call last for each vertex, adds the above attributes.
st.AddVertex(new Vector3(-1, -1, 0));
st.SetNormal(new Vector3(0, 0, 1));
st.SetUV(new Vector2(0, 1));
st.AddVertex(new Vector3(-1, 1, 0));
st.SetNormal(new Vector3(0, 0, 1));
st.SetUV(new Vector2(1, 1));
st.AddVertex(new Vector3(1, 1, 0));
// Commit to a mesh.
var mesh = st.Commit();
You can optionally add an index array, either by calling ``add_index()`` and adding
vertices to the index array manually, or by calling ``index()`` once,
which generates the index array automatically and
shrinks the vertex array to remove duplicate vertices.
.. tabs::
.. code-tab:: gdscript GDScript
# Suppose we have a quad defined by 6 vertices as follows
st.add_vertex(Vector3(-1, 1, 0))
st.add_vertex(Vector3(1, 1, 0))
st.add_vertex(Vector3(-1, -1, 0))
st.add_vertex(Vector3(1, 1, 0))
st.add_vertex(Vector3(1, -1, 0))
st.add_vertex(Vector3(-1, -1, 0))
# We can make the quad more efficient by using an index array and only utilizing 4 vertices
# Suppose we have a quad defined by 6 vertices as follows
st.add_vertex(Vector3(-1, 1, 0))
st.add_vertex(Vector3(1, 1, 0))
st.add_vertex(Vector3(-1, -1, 0))
st.add_vertex(Vector3(1, 1, 0))
st.add_vertex(Vector3(1, -1, 0))
st.add_vertex(Vector3(-1, -1, 0))
# We can make the quad more efficient by using an index array and only utilizing 4 vertices
# Creates a quad from four corner vertices.
# add_index() can be called before or after add_vertex()
# since it's not an attribute of a vertex itself.
st.add_index(0)
st.add_index(1)
st.add_index(2)
st.add_index(1)
st.add_index(3)
st.add_index(2)
# Alternatively we can use ``st.index()`` which will create the quad for us and remove the duplicate vertices
st.index()
.. code-tab:: csharp
// Creates a quad from four corner vertices.
// AddIndex does not need to be called before AddVertex.
st.AddIndex(0);
st.AddIndex(1);
st.AddIndex(2);
st.AddIndex(1);
st.AddIndex(3);
st.AddIndex(2);
// Alternatively:
st.Index();
Similarly, if you have an index array, but you want each vertex to be unique (e.g. because
you want to use unique normals or colors per face instead of per-vertex), you can call ``deindex()``.
.. tabs::
.. code-tab:: gdscript GDScript
st.deindex()
.. code-tab:: csharp
st.Deindex();
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 ``commit()`` 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``.
You may notice that normal mapping or other material properties look broken on
the generated mesh. This is because normal mapping **requires** the mesh to
feature *tangents*, which are separate from *normals*. You can either add custom
tangents manually, or generate them automatically with
``generate_tangents()``. This method requires that each vertex have UVs and
normals set already.
.. tabs::
.. code-tab:: gdscript GDScript
st.generate_normals()
st.generate_tangents()
st.commit(mesh)
.. code-tab:: csharp
st.GenerateNormals();
st.GenerateTangents();
By default, when generating normals, they will be calculated on a per-vertex basis (i.e. they will
be "smooth normals"). If you want flat vertex normals (i.e. a single normal vector per face), when
adding vertices, call ``add_smooth_group(i)`` where ``i`` is a unique number per vertex.
``add_smooth_group()`` needs to be called while building the geometry, e.g. before the call to
``add_vertex()``.