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3791d83a0b
`vertex_array` is defined as a Vector3, but it only contains 2 elements (I assume this was a mistake). So I have added the third element (being 0) to complete the size (i.e. make it a 3-component vector). These vertex vectors should now define the coordinates of a triangle in 3D space.
145 lines
4.0 KiB
ReStructuredText
145 lines
4.0 KiB
ReStructuredText
.. _doc_procedural_geometry:
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Procedural geometry generation
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==============================
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Users often ask how to generate geometry from code. This is not very complicated, but it's not obvious.
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Godot provides a few classes entirely dedicated to make it this easy. Still, the best tool for the job depends
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entirely on the use case.
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SurfaceTool
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-----------
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This is the most common helper. :ref:`SurfaceTool<class_SurfaceTool>` is a class you can instantiate to generate :ref:`Meshes<class_Mesh>`, specifically *Mesh Surfaces*.
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It has a similar API to OpenGL 1.x, and it's meant for static content. This means, the mesh is generated once and then used.
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Here is a simple example of how to use it to add a single triangle.
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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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# Create indices, indices are optional.
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st.index()
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# Commit to a mesh.
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var mesh = st.commit()
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Just explore the APIs and the possibilities.
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ImmediateGeometry
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-----------------
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Unlike *SurfaceTool*, :ref:`ImmediateGeometry<class_ImmediateGeometry>` is an actual node. It's similar in the "OpenGL 1.x" style API,
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but it's actually designed to create content on the fly and modify it every frame efficiently.
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Generating complex geometry (several thousand vertices) with this node is inefficient, even if it's done only once. Instead, *ImmediateGeometry* is designed to generate simple geometry that changes every frame.
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It's used similar to *SurfaceTool*.
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.. tabs::
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.. code-tab:: gdscript GDScript
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extends ImmediateGeometry
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void _process(delta):
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# Clean up before drawing.
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clear()
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# Begin draw.
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begin(Mesh.PRIMITIVE_TRIANGLES)
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# Prepare attributes for add_vertex.
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set_normal( Vector3(0, 0, 1))
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set_uv(Vector2(0, 0))
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# Call last for each vertex, adds the above attributes.
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add_vertex(Vector3(-1, -1, 0))
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set_normal(Vector3(0, 0, 1))
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set_uv(Vector2(0, 1))
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add_vertex(Vector3(-1, 1, 0))
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set_normal(Vector3(0, 0, 1))
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set_uv(Vector2(1, 1))
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add_vertex(Vector3(1, 1, 0))
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# End drawing.
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end()
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Arrays
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------
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Lastly, the final way to do this is to create arrays themselves. This is the most efficient way to create static geometry, and is only
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recommended when SurfaceTool is not fast enough.
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Similar code as before, but draw a square using indices:
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.. tabs::
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.. code-tab:: gdscript GDScript
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var arrays = []
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arrays.resize(Mesh.ARRAY_MAX)
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var normal_array = []
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var uv_array = []
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var vertex_array = []
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var index_array = []
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normal_array.resize(4)
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uv_array.resize(4)
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vertex_array.resize(4)
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index_array.resize(6)
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normal_array[0] = Vector3(0, 0, 1)
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uv_array[0] = Vector2(0, 0)
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vertex_array[0] = Vector3(-1, -1, 0)
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normal_array[1] = Vector3(0, 0, 1)
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uv_array[1] = Vector2(0,1)
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vertex_array[1] = Vector3(-1, 1, 0)
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normal_array[2] = Vector3(0, 0, 1)
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uv_array[2] = Vector2(1, 1)
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vertex_array[2] = Vector3(1, 1, 0)
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normal_array[3] = Vector3(0, 0, 1)
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uv_array[3] = Vector2(1, 0)
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vertex_array[3] = Vector3(1, -1, 0)
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# Indices are optional in Godot, but if they exist they are used.
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index_array[0] = 0
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index_array[1] = 1
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index_array[2] = 2
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index_array[3] = 2
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index_array[4] = 3
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index_array[5] = 0
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arrays[Mesh.ARRAY_VERTEX] = vertex_array
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arrays[Mesh.ARRAY_NORMAL] = normal_array
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arrays[Mesh.ARRAY_TEX_UV] = uv_array
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arrays[Mesh.ARRAY_INDEX] = index_array
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var mesh = ArrayMesh.new()
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mesh.add_surface_from_arrays(Mesh.PRIMITIVE_TRIANGLES,arrays)
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