generate mesh via code in gdscript example

GenerateMesh.gd

extends MeshInstance
""" 
Example:
	godot arrayMesh generate a box geometry
"""
var rings = 50
var radial_segments = 50
var radius = 1

export(float) var width_fwd = 1
export(float) var width_back = 1
export(float) var height_fwd = 1
export(float) var height_back = 1
export(float) var depth_left = 0.5
export(float) var depth_right = 0.5

# Called when the node enters the scene tree for the first time.
func _ready():
	var arr = []
	arr.resize(Mesh.ARRAY_MAX)
	var verts = PoolVector3Array()
	var uvs = PoolVector2Array()
	var normals = PoolVector3Array()
	var indices = PoolIntArray()

	# generate a sphere

	
	"""
 	# 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 
	"""

	var vts = [
		Vector3.ZERO,
		Vector3(width_fwd, 0, 0),
		Vector3(0, height_fwd, 0),
		Vector3(width_fwd, height_fwd, 0),
		Vector3(0, 0, -depth_left),
		Vector3(width_back, 0, -depth_right),
		Vector3(0, height_back, -depth_left),
		Vector3(width_back, height_back, -depth_right)
	]
	verts.append_array(vts)
	
	var faces = 6
	for n in range(0, faces):
		uvs.append_array([ Vector2.ZERO, Vector2(0, 1), Vector2(1,0), Vector2(0,1), Vector2(1,1), Vector2(1,0) ])

	normals.append_array([
				Vector3.FORWARD,Vector3.FORWARD,Vector3.FORWARD,Vector3.FORWARD,Vector3.FORWARD,Vector3.FORWARD,
				-Vector3.RIGHT,-Vector3.RIGHT,-Vector3.RIGHT,-Vector3.RIGHT,-Vector3.RIGHT,-Vector3.RIGHT,
				Vector3.RIGHT,Vector3.RIGHT,Vector3.RIGHT,Vector3.RIGHT,Vector3.RIGHT,Vector3.RIGHT,
				Vector3.UP, Vector3.UP, Vector3.UP, Vector3.UP, Vector3.UP, Vector3.UP,
				-Vector3.UP, -Vector3.UP, -Vector3.UP, -Vector3.UP, -Vector3.UP, -Vector3.UP,
				-Vector3.FORWARD,-Vector3.FORWARD,-Vector3.FORWARD,-Vector3.FORWARD,-Vector3.FORWARD,-Vector3.FORWARD
			])

	# indices.append_array([0,2,1,2,3,1])
	indices.append_array([0,2,1,2,3,1, 4,6,0,6,2,0])
	indices.append_array([1,3,5,3,7,5, 2,6,3,6,7,3])
	indices.append_array([4,0,5,0,1,5, 5,7,4,7,6,4])
	# indices.append_array([0,1,2,3,4,5])

	verts.resize(indices.size())
	# print('indices: %s, verts: %s' % indices.size(), verts.size())

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


	mesh = ArrayMesh.new()
	mesh.add_surface_from_arrays(Mesh.PRIMITIVE_TRIANGLES, arr)

pass # Replace with function body.


# Called every frame. 'delta' is the elapsed time since the previous frame.
#func _process(delta):
#	pass