extends MeshInstance3D

var mat: StandardMaterial3D
var ang: float = 0.0
var poslist: PackedVector3Array = PackedVector3Array()

func _ready():
	mat = StandardMaterial3D.new()
	mat.albedo_color = Color(1, 0, 0, 0.5)
	mat.cull_mode = BaseMaterial3D.CULL_DISABLED
	mat.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
	# mat.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
	
	mesh = ImmediateMesh.new()
	
	var n = 30
	for i in range(0, n, 1):
		poslist.append(Vector3.ZERO)


func _process(delta):
	
	# store positon to PackedVector3Array
	for i in range(0, poslist.size(), 1):
		var x1 = 6.0 + 4.0 * sin(deg_to_rad((ang + 10 * i) * 0.75))
		var y1 = 4.0 + 4.0 * sin(deg_to_rad(ang + 10 * i))
		var z1 = 10 - 1.0 * i
		poslist[i] = Vector3(x1, y1, z1)

	# set ImmediateMesh
	mesh.clear_surfaces()
	mesh.surface_begin(Mesh.PRIMITIVE_TRIANGLES, mat)
	# mesh.surface_set_color(Color.WHITE)
	for i in range(1, poslist.size(), 1):
		var v0 = poslist[i - 1]
		var v1 = poslist[i]
		mesh.surface_add_vertex(Vector3(v1.x, v1.y, v1.z))
		mesh.surface_add_vertex(Vector3(v0.x + 0.5, v0.y, v0.z))
		mesh.surface_add_vertex(Vector3(v0.x - 0.5, v0.y, v0.z))
	
	mesh.surface_end()
	
	ang += 120.0 * delta