extends MeshInstance3D

@export var normal : Vector3

func regenerate_mesh():
	var arrays := []
	arrays.resize(Mesh.ARRAY_MAX)
	
	var vertex_array := PackedVector3Array()
	var uv_array := PackedVector2Array()
	var normal_array := PackedVector3Array()
	
	var index_array := PackedInt32Array()
	
	var resolution := 5
	var num_vertices : int = resolution * resolution
	var num_indices : int = (resolution-1) * (resolution-1) * 6
	
	vertex_array.resize(num_vertices)
	normal_array.resize(num_vertices)
	uv_array.resize(num_vertices)
	index_array.resize(num_indices)
	
	var tri_index : int = 0
	var a_axis := Vector3(normal.y, normal.z, normal.z)
	var b_axis : Vector3 = normal.cross(a_axis)
	for y in range(resolution):
		for x in range(resolution):
			var i : int = x + y*resolution
			var percent := Vector2(x,y) / (resolution-1)
			var point_on_cube : Vector3 = normal + (percent.x - 0.5)*2.0*a_axis + (percent.y - 0.5)*2.0*b_axis
			vertex_array[i] = point_on_cube
			if x != resolution-1 and y != resolution-1:
				index_array[tri_index + 2] = i
				index_array[tri_index + 1] = i+resolution+1
				index_array[tri_index] = i+resolution
				
				index_array[tri_index + 5] = i
				index_array[tri_index + 4] = i+1
				index_array[tri_index + 3] = i+resolution+1
				tri_index += 6