extends MultiMeshInstance3D

@export_range(1, 126) var shell_count = 64
@export var noise_min: float = 0.4
@export var noise_max: float = 1.0
@export var shell_length: float = .1
@export var shell_distance_attenuation: float = 1.
@export var thickness: float = 3.4
@export var attenuation: float = 1.98
@export var occlusion_bias: float = .04
@export var shell_color: Vector3 = Vector3(0.2, 0.7, 0.2)
@export var density: int = 150

func _generate_mmi(layers: int, mmi: MultiMeshInstance3D, mesh: Mesh, material: Material, cast_shadow: bool):
	var mdt = MeshDataTool.new()
	
	if mmi.multimesh == null:
		mmi.multimesh = MultiMesh.new()
		mmi.multimesh.transform_format = MultiMesh.TRANSFORM_3D
	
	var new_mesh: Mesh = mesh.duplicate(true) as Mesh
	#new_mesh = _normals_to_vertex_color(new_mesh, material)  # saves normal data as vertex color to be used by the shader (in the orig code)
	mmi.multimesh.mesh = new_mesh
	mmi.multimesh.instance_count = layers
	mmi.multimesh.visible_instance_count = layers
	for surface in new_mesh.get_surface_count():
		material = ShaderMaterial.new()
		material.set_shader(preload("res://grass.gdshader"))
		mmi.multimesh.mesh.surface_set_material(surface, material.duplicate(true))
	
	for i in range(layers):
		#mmi.multimesh.set_instance_transform(i, Transform3D(Basis(), Vector3(0., .1 * i, 0.)))
		mmi.multimesh.set_instance_transform(i, Transform3D(Basis(), Vector3()))
		var grey = float(i) / float(layers)
		#mmi.multimesh.set_instance_color(i, Color(1., 1., 1., 1.))
		
		var mat = mmi.multimesh.mesh.surface_get_material(0)
		if mat is ShaderMaterial:
			#print("Setting shader params (", i, ")")
			#mat.set_shader_parameter("_ShellIndex", i)
			mmi.multimesh.set_instance_custom_data(i, Color(i, 0., 0., 0.))  # passes shell index for each instance
			mat.set_shader_parameter("_NoiseMin", noise_min)
			mat.set_shader_parameter("_NoiseMax", noise_max)
			mat.set_shader_parameter("_ShellLength", shell_length)
			mat.set_shader_parameter("_ShellCount", layers)
			mat.set_shader_parameter("_ShellDistanceAttenuation", shell_distance_attenuation)
			mat.set_shader_parameter("_Thickness", thickness)
			mat.set_shader_parameter("_Attenuation", attenuation)
			mat.set_shader_parameter("_OcclusionBias", occlusion_bias)
			mat.set_shader_parameter("_ShellColor", shell_color)
			mat.set_shader_parameter("_Density", density)
	
	mmi.cast_shadow = 1 if cast_shadow else 0

func _ready():
	var mat = ShaderMaterial.new()
	#var mat2 = StandardMaterial3D.new()
	mat.set_shader(preload("res://grass.gdshader"))
	self._generate_mmi(self.shell_count, self, self.get_multimesh().mesh, mat, false)
	
	print("===== Shell Texturing =====")
	print("Layers: ", self.shell_count)
	print("Noise (min): ", self.noise_min)
	print("Noise (max): ", self.noise_max)
	print("Shell length: ", self.shell_length)
	print("Shell count: ", self.shell_count)
	print("Shell distance attenuation: ", self.shell_distance_attenuation)
	print("Thickness: ", self.thickness)
	print("Attenuation: ", self.attenuation)
	print("Occlusion bias: ", self.occlusion_bias)
	print("Shell color: ", self.shell_color)
	print("Density: ", self.density)