Godot 3.1 Vector2.cubic_interpolate() demo

CubicInterp.tscn

[gd_scene load_steps=2 format=2]

[sub_resource type="GDScript" id=2]

script/source = "extends GraphEdit

func _process(delta):
	update()

func _draw():
	var a = $A.rect_global_position
	var b = $B.rect_global_position
	var pre_a= $PreA.rect_global_position
	var post_b= $PostB.rect_global_position
	var line = []
	
	var times = 100.0
	for i in range(times):
		var value = i / times
		var pos = a.cubic_interpolate(b, pre_a, post_b, value)
		line.append(pos)
	
	draw_polyline(line, Color.white, 2, true)
	draw_line(a, pre_a, Color.red, 1, true)
	draw_line(b, post_b, Color.green, 1, true)
	draw_line(pre_a, post_b, Color.blue, 1, true)"

[node name="CubicInterp" type="Control"]
anchor_right = 1.0
anchor_bottom = 1.0

[node name="GraphicEditor" type="GraphEdit" parent="."]
anchor_right = 1.0
anchor_bottom = 1.0
use_snap = false
script = SubResource( 2 )

[node name="A" type="GraphNode" parent="GraphicEditor"]
modulate = Color( 1, 1, 1, 0.501961 )
margin_left = 800.0
margin_top = 450.0
margin_right = 841.0
margin_bottom = 479.0
rect_pivot_offset = Vector2( 20, 14 )
mouse_filter = 1
mouse_default_cursor_shape = 2
title = "A"
offset = Vector2( 800, 450 )

[node name="B" type="GraphNode" parent="GraphicEditor"]
modulate = Color( 1, 1, 1, 0.501961 )
margin_left = 800.0
margin_top = 450.0
margin_right = 841.0
margin_bottom = 479.0
rect_pivot_offset = Vector2( 20, 14 )
mouse_filter = 1
mouse_default_cursor_shape = 2
title = "B"
offset = Vector2( 800, 450 )

[node name="PreA" type="GraphNode" parent="GraphicEditor"]
modulate = Color( 1, 1, 1, 0.501961 )
margin_left = 800.0
margin_top = 450.0
margin_right = 862.0
margin_bottom = 479.0
rect_pivot_offset = Vector2( 31, 14.5 )
mouse_filter = 1
mouse_default_cursor_shape = 2
title = "PreA"
offset = Vector2( 800, 450 )

[node name="PostB" type="GraphNode" parent="GraphicEditor"]
modulate = Color( 1, 1, 1, 0.501961 )
margin_left = 800.0
margin_top = 450.0
margin_right = 869.0
margin_bottom = 479.0
rect_pivot_offset = Vector2( 34.5, 14.5 )
mouse_filter = 1
mouse_default_cursor_shape = 2
title = "PostB"
offset = Vector2( 800, 450 )