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108 lines
3.5 KiB
ReStructuredText
108 lines
3.5 KiB
ReStructuredText
.. _doc_surfacetool:
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Using the SurfaceTool
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=====================
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The :ref:`SurfaceTool <class_surfacetool>` provides a useful interface for constructing geometry.
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The interface is similar to the :ref:`ImmediateGeometry <class_immediategeometry>` node. You
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set each per-vertex attribute (e.g. normal, uv, color) and then when you add a vertex it
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captures the attributes.
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The SurfaceTool also provides some useful helper functions like ``index()`` and ``generate_normals()``.
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Attributes are added before each vertex is added:
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.. tabs::
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.. code-tab:: gdscript GDScript
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st.add_normal() # Overwritten by normal below.
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st.add_normal() # Added to next vertex.
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st.add_color() # Added to next vertex.
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st.add_vertex() # Captures normal and color above.
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st.add_normal() # Normal never added to a vertex.
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When finished generating your geometry with the :ref:`SurfaceTool <class_surfacetool>`
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call ``commit()`` to finish generating the mesh. If an :ref:`ArrayMesh <class_ArrayMesh>` is passed
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to ``commit()`` then it appends a new surface to the end of the ArrayMesh. While if nothing is passed
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in, ``commit()`` returns an ArrayMesh.
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.. tabs::
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.. code-tab:: gdscript GDScript
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st.commit(mesh)
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# Or:
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var mesh = st.commit()
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Code creates a triangle with indices
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.. tabs::
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.. code-tab:: gdscript GDScript
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var st = SurfaceTool.new()
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st.begin(Mesh.PRIMITIVE_TRIANGLES)
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# Prepare attributes for add_vertex.
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st.add_normal(Vector3(0, 0, 1))
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st.add_uv(Vector2(0, 0))
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# Call last for each vertex, adds the above attributes.
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st.add_vertex(Vector3(-1, -1, 0))
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st.add_normal(Vector3(0, 0, 1))
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st.add_uv(Vector2(0, 1))
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st.add_vertex(Vector3(-1, 1, 0))
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st.add_normal(Vector3(0, 0, 1))
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st.add_uv(Vector2(1, 1))
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st.add_vertex(Vector3(1, 1, 0))
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# Commit to a mesh.
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var mesh = st.commit()
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You can optionally add an index array, either by calling ``add_index()`` and adding
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vertices to the index array or by calling ``index()`` which shrinks the vertex array
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to remove duplicate vertices.
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.. tabs::
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.. code-tab:: gdscript GDScript
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# Creates a quad from four corner vertices.
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# Add_index does not need to be called before add_vertex.
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st.add_index(0)
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st.add_index(1)
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st.add_index(2)
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st.add_index(1)
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st.add_index(3)
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st.add_index(2)
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# Alternatively:
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st.index()
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Similarly, if you have an index array, but you want each vertex to be unique (e.g. because
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you want to use unique normals or colors per face instead of per-vertex), you can call ``deindex()``.
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.. tabs::
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.. code-tab:: gdscript GDScript
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st.deindex()
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If you don't add custom normals yourself, you can add them using ``generate_normals()``, which should
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be called after generating geometry and before committing the mesh using ``commit()`` or
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``commit_to_arrays()``. Calling ``generate_normals(true)`` will flip the resulting normals. As a side
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note, ``generate_normals()`` only works if the primitive type is set to ``Mesh.PRIMITIVE_TRIANGLES``.
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If you don't add custom tangents, they can be added with ``generate_tangents()``, but it requires
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that each vertex have UVs and normals set already.
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.. tabs::
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.. code-tab:: gdscript GDScript
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st.generate_normals()
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st.generate_tangents()
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By default, when generating normals, they will be calculated on a per-face basis. If you want
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smooth vertex normals, when adding vertices, call ``add_smooth_group()``. ``add_smooth_group()``
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needs to be called while building the geometry, e.g. before the call to ``add_vertex()``
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(if non-indexed) or ``add_index()`` (if indexed).
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