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Utilisation du ArrayMesh

Ce tutoriel présente les bases de l'utilisation d'un ArrayMesh.

To do so, we will use the function add_surface_from_arrays(), which takes up to five parameters. The first two are required, while the last three are optional.

The first parameter is the PrimitiveType, an OpenGL concept that instructs the GPU how to arrange the primitive based on the vertices given, i.e. whether they represent triangles, lines, points, etc. See Mesh.PrimitiveType for the options available.

The second parameter, arrays, is the actual Array that stores the mesh information. The array is a normal Godot array that is constructed with empty brackets []. It stores a Packed**Array (e.g. PackedVector3Array, PackedInt32Array, etc.) for each type of information that will be used to build the surface.

Common elements of arrays are listed below, together with the position they must have within arrays. See Mesh.ArrayType for a full list.

Index

Mesh.ArrayType Enum

Array type

0

ARRAY_VERTEX

PackedVector3Array or PackedVector2Array

1

ARRAY_NORMAL

PackedVector3Array

2

ARRAY_TANGENT

PackedFloat32Array or PackedFloat64Array of groups of 4 floats. The first 3 floats determine the tangent, and the last float the binormal direction as -1 or 1.

3

ARRAY_COLOR

PackedColorArray

4

ARRAY_TEX_UV

PackedVector2Array or PackedVector3Array

5

ARRAY_TEX_UV2

PackedVector2Array or PackedVector3Array

10

ARRAY_BONES

PackedFloat32Array of groups of 4 floats or PackedInt32Array of groups of 4 ints. Each group lists indexes of 4 bones that affects a given vertex.

11

ARRAY_WEIGHTS

PackedFloat32Array or PackedFloat64Array of groups of 4 floats. Each float lists the amount of weight the corresponding bone in ARRAY_BONES has on a given vertex.

12

ARRAY_INDEX

PackedInt32Array

In most cases when creating a mesh, we define it by its vertex positions. So usually, the array of vertices (at index 0) is required, while the index array (at index 12) is optional and will only be used if included. It is also possible to create a mesh with only the index array and no vertex array, but that's beyond the scope of this tutorial. In fact, we won't use the index array at all.

All the other arrays carry information about the vertices. They are optional and will only be used if included. Some of these arrays (e.g. ARRAY_COLOR) use one entry per vertex to provide extra information about vertices. They must have the same size as the vertex array. Other arrays (e.g. ARRAY_TANGENT) use four entries to describe a single vertex. These must be exactly four times larger than the vertex array.

For normal usage, the last three parameters in add_surface_from_arrays() are typically left empty.

Setting up the ArrayMesh

In the editor, create a MeshInstance3D and add an ArrayMesh to it in the Inspector. Normally, adding an ArrayMesh in the editor is not useful, but in this case it allows us to access the ArrayMesh from code without creating one.

Next, add a script to the MeshInstance3D.

Sous _ready(), créez un nouvel Array.

var surface_array = []

This will be the array that we keep our surface information in - it will hold all the arrays of data that the surface needs. Godot will expect it to be of size Mesh.ARRAY_MAX, so resize it accordingly.

var surface_array = []
surface_array.resize(Mesh.ARRAY_MAX)

Créez ensuite les arrays pour chaque type de données que vous utiliserez.

var verts = PackedVector3Array()
var uvs = PackedVector2Array()
var normals = PackedVector3Array()
var indices = PackedInt32Array()

Une fois que vous avez rempli vos arrays de données avec votre géométrie, vous pouvez créer un maillage en ajoutant chaque array à surface_array, puis en validant le maillage.

surface_array[Mesh.ARRAY_VERTEX] = verts
surface_array[Mesh.ARRAY_TEX_UV] = uvs
surface_array[Mesh.ARRAY_NORMAL] = normals
surface_array[Mesh.ARRAY_INDEX] = indices

# No blendshapes, lods, or compression used.
mesh.add_surface_from_arrays(Mesh.PRIMITIVE_TRIANGLES, surface_array)

Note

Dans cet exemple, nous avons utilisé Mesh.PRIMITIVE_TRIANGLES, mais vous pouvez utiliser n'importe quel type primitif disponible à partir de mesh.

Mis ensemble, le code complet ressemble à ceci :

extends MeshInstance3D

func _ready():
    var surface_array = []
    surface_array.resize(Mesh.ARRAY_MAX)

    # PackedVector**Arrays for mesh construction.
    var verts = PackedVector3Array()
    var uvs = PackedVector2Array()
    var normals = PackedVector3Array()
    var indices = PackedInt32Array()

    #######################################
    ## Insert code here to generate mesh ##
    #######################################

    # Assign arrays to surface array.
    surface_array[Mesh.ARRAY_VERTEX] = verts
    surface_array[Mesh.ARRAY_TEX_UV] = uvs
    surface_array[Mesh.ARRAY_NORMAL] = normals
    surface_array[Mesh.ARRAY_INDEX] = indices

    # Create mesh surface from mesh array.
    # No blendshapes, lods, or compression used.
    mesh.add_surface_from_arrays(Mesh.PRIMITIVE_TRIANGLES, surface_array)

The code that goes in the middle can be whatever you want. Below we will present some example code for generating a sphere.

Génération de la géométrie

Voici un exemple de code pour générer une sphère. Bien que le code soit présenté en GDScript, il n'y a rien de spécifique à Godot dans l'approche de sa génération. Cette implémentation n'a rien de particulier à voir avec ArrayMeshes et n'est qu'une approche générique pour générer une sphère. Si vous avez du mal à comprendre ou si vous souhaitez en savoir plus sur la géométrie procédurale en général, vous pouvez utiliser n'importe quel tutoriel que vous trouverez en ligne.

extends MeshInstance3D

var rings = 50
var radial_segments = 50
var radius = 1

func _ready():

    # Insert setting up the PackedVector**Arrays here.

    # Vertex indices.
    var thisrow = 0
    var prevrow = 0
    var point = 0

    # Loop over rings.
    for i in range(rings + 1):
        var v = float(i) / rings
        var w = sin(PI * v)
        var y = cos(PI * v)

        # Loop over segments in ring.
        for j in range(radial_segments):
            var u = float(j) / radial_segments
            var x = sin(u * PI * 2.0)
            var z = cos(u * PI * 2.0)
            var vert = Vector3(x * radius * w, y * radius, z * radius * w)
            verts.append(vert)
            normals.append(vert.normalized())
            uvs.append(Vector2(u, v))
            point += 1

            # Create triangles in ring using indices.
            if i > 0 and j > 0:
                indices.append(prevrow + j - 1)
                indices.append(prevrow + j)
                indices.append(thisrow + j - 1)

                indices.append(prevrow + j)
                indices.append(thisrow + j)
                indices.append(thisrow + j - 1)

        if i > 0:
            indices.append(prevrow + radial_segments - 1)
            indices.append(prevrow)
            indices.append(thisrow + radial_segments - 1)

            indices.append(prevrow)
            indices.append(prevrow + radial_segments)
            indices.append(thisrow + radial_segments - 1)

        prevrow = thisrow
        thisrow = point

  # Insert committing to the ArrayMesh here.

Enregistrer

Finally, we can use the ResourceSaver class to save the ArrayMesh. This is useful when you want to generate a mesh and then use it later without having to re-generate it.

# Saves mesh to a .tres file with compression enabled.
ResourceSaver.save(mesh, "res://sphere.tres", ResourceSaver.FLAG_COMPRESS)