MeshDataToolの使用

The MeshDataTool is not used to generate geometry. But it is helpful for dynamically altering geometry, for example if you want to write a script to tessellate, simplify, or deform meshes.

MeshDataToolは、ArrayMeshを使用して配列を直接変更するほど高速ではありません。ただし、ArrayMeshよりも多くの情報とメッシュを操作するツールを提供します。 MeshDataToolを使用すると、特定のメッシュアルゴリズムに必要なFace(面)やEdge(エッジ/辺)などのArrayMeshでは使用できないメッシュデータが計算されます。この追加情報が必要ない場合は、ArrayMeshを使用することをお勧めします。

注釈

MeshDataToolは、PrimitiveType Mesh.PRIMITIVE_TRIANGLES を使用するメッシュでのみ使用できます。

We initialize the MeshDataTool from an ArrayMesh by calling create_from_surface(). If there is already data initialized in the MeshDataTool, calling create_from_surface() will clear it for you. Alternatively, you can call clear() yourself before re-using the MeshDataTool.

In the examples below, assume an ArrayMesh called mesh has already been created. See ArrayMesh tutorial for an example of mesh generation.

GDScript

var mdt = MeshDataTool.new()
mdt.create_from_surface(mesh, 0)

create_from_surface() uses the vertex arrays from the ArrayMesh to calculate two additional arrays, one for edges and one for faces, for a total of three arrays.

エッジは、任意の2つの頂点間の接続です。エッジ配列の各エッジには、それが構成する2つの頂点への参照と、それが含まれる最大2つの面が含まれます。

A face is a triangle made up of three vertices and three corresponding edges. Each face in the face array contains a reference to the three vertices and three edges it is composed of.

The vertex array contains edge, face, normal, color, tangent, uv, uv2, bone, and weight information connected with each vertex.

これらの配列から情報にアクセスするには、get _****() 形式の関数を使用します:

GDScript

mdt.get_vertex_count() # Returns number of vertices in vertex array.
mdt.get_vertex_faces(0) # Returns array of faces that contain vertex[0].
mdt.get_face_normal(1) # Calculates and returns face normal of the second face.
mdt.get_edge_vertex(10, 1) # Returns the second vertex comprising the edge at index 10.

これらの関数で何をするかはあなた次第です。一般的な使用例は、すべての頂点を反復処理し、何らかの方法で変換することです。

GDScript

for i in range(get_vertex_count):
    var vert = mdt.get_vertex(i)
    vert *= 2.0 # Scales the vertex by doubling size.
    mdt.set_vertex(i, vert)

These modifications are not done in place on the ArrayMesh. If you are dynamically updating an existing ArrayMesh, first delete the existing surface before adding a new one using commit_to_surface():

GDScript

mesh.surface_remove(0) # Deletes the first surface of the mesh.
mdt.commit_to_surface(mesh)

Below is a complete example that turns a spherical mesh called mesh into a randomly deformed blob complete with updated normals and vertex colors. See ArrayMesh tutorial for how to generate the base mesh.

GDScript

extends MeshInstance

var sn = OpenSimplexNoise.new()
var mdt = MeshDataTool.new()

func _ready():
    sn.period = 0.7

    mdt.create_from_surface(mesh, 0)

    for i in range(mdt.get_vertex_count()):
        var vertex = mdt.get_vertex(i).normalized()
        # Push out vertex by noise.
        vertex = vertex * (sn.get_noise_3dv(vertex) * 0.5 + 0.75)
        mdt.set_vertex(i, vertex)

    # Calculate vertex normals, face-by-face.
    for i in range(mdt.get_face_count()):
        # Get the index in the vertex array.
        var a = mdt.get_face_vertex(i, 0)
        var b = mdt.get_face_vertex(i, 1)
        var c = mdt.get_face_vertex(i, 2)
        # Get vertex position using vertex index.
        var ap = mdt.get_vertex(a)
        var bp = mdt.get_vertex(b)
        var cp = mdt.get_vertex(c)
        # Calculate face normal.
        var n = (bp - cp).cross(ap - bp).normalized()
        # Add face normal to current vertex normal.
        # This will not result in perfect normals, but it will be close.
        mdt.set_vertex_normal(a, n + mdt.get_vertex_normal(a))
        mdt.set_vertex_normal(b, n + mdt.get_vertex_normal(b))
        mdt.set_vertex_normal(c, n + mdt.get_vertex_normal(c))

    # Run through vertices one last time to normalize normals and
    # set color to normal.
    for i in range(mdt.get_vertex_count()):
        var v = mdt.get_vertex_normal(i).normalized()
        mdt.set_vertex_normal(i, v)
        mdt.set_vertex_color(i, Color(v.x, v.y, v.z))

    mesh.surface_remove(0)
    mdt.commit_to_surface(mesh)