Utilisation du ArrayMesh

This tutorial will present the basics of using an ArrayMesh.

Pour ce faire, nous utiliserons la fonction add_surface_from_arrays(), qui prend jusqu'à quatre paramètres. Les deux premiers sont obligatoires, tandis que les deux autres sont facultatifs.

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 Pool**Array (e.g. PoolVector3Array, PoolIntArray, etc.) for each type of information that will be used to build the surface.

The possible elements of arrays are listed below, together with the position they must have within arrays. See also Mesh.ArrayType.

Index

Mesh.ArrayType Enum

Array type

0

ARRAY_VERTEX

PoolVector3Array or PoolVector2Array

1

ARRAY_NORMAL

PoolVector3Array

2

ARRAY_TANGENT

PoolRealArray of groups of 4 floats. First 3 floats determine the tangent, and the last the binormal direction as -1 or 1.

3

ARRAY_COLOR

PoolColorArray

4

ARRAY_TEX_UV

PoolVector2Array or PoolVector3Array

5

ARRAY_TEX_UV2

PoolVector2Array or PoolVector3Array

6

ARRAY_BONES

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

7

ARRAY_WEIGHTS

PoolRealArray of groups of 4 floats. Each float lists the amount of weight an determined bone on ARRAY_BONES has on a given vertex.

8

ARRAY_INDEX

PoolIntArray

The array of vertices (at index 0) is always required. The index array is optional and will only be used if included. We won't use it in this tutorial.

All the other arrays carry information about the vertices. They are also 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 two parameters in add_surface_from_arrays() are typically left empty.

ArrayMesh

In the editor, create a MeshInstance 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.

Ensuite, ajoutez un script au MeshInstance.

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 = PoolVector3Array()
var uvs = PoolVector2Array()
var normals = PoolVector3Array()
var indices = PoolIntArray()

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

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

Note

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

Put together, the full code looks like:

extends MeshInstance

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

    # PoolVector**Arrays for mesh construction.
    var verts = PoolVector3Array()
    var uvs = PoolVector2Array()
    var normals = PoolVector3Array()
    var indices = PoolIntArray()

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

    # Assign arrays to mesh 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.
    mesh.add_surface_from_arrays(Mesh.PRIMITIVE_TRIANGLES, surface_array) # No blendshapes or compression used.

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 MeshInstance

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

func _ready():

    # Insert setting up the PoolVector**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, 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("res://sphere.tres", mesh, ResourceSaver.FLAG_COMPRESS)