extends SceneTree

## Fixed simulation step — see _lock_timestep.
const STEP := 1.0 / 60.0

## Dev tool: is the thigh THROUGH the skirt, or just showing past its edge?
##
##   godot --path . --windowed --resolution 900x900 \
##       -s res://debug/skirt_clip_view.gd -- <out_dir> [skin]
##
## debug/skirt_closeup.gd renders the character as it ships, and at that point
## the two failures look identical: a wedge of thigh against dark cloth reads the
## same whether the leg is in front of a panel or simply visible between two of
## them. Both were guessed at, in both directions, before this existed.
##
## So: every cloth surface is painted flat MAGENTA and the body flat GREY,
## unshaded, no outline.
##
## Alongside each pair it writes `hip_N.txt`: the screen row of the hip joint.
## tools/measure_clipview.py counts only BELOW that line, because the torso is
## legitimately in front of the skirt's waistband and counting it reported 5% of
## the cloth covered on a pose that is actually clean. Colouring the legs
## separately does not work — the bare thigh is part of the body mesh, and a
## per-surface colour caught only the boots. Cloth is then a solid silhouette, and the question
## has one answer — any grey inside the magenta is the leg in front of the skirt,
## and grey outside it is just the leg past the hem, which is correct.
##
## Each shot is saved twice: `clipview_N` with the whole character, and
## `cloth_N` with the body hidden. A grey wedge that is a HOLE in the cloth-only
## image is the leg showing between two panels that have drifted apart, which is
## a different bug with a different fix; a grey wedge over solid magenta is the
## leg in front of the cloth.
##
## Cloth is identified from the skin itself (a surface whose vertices are mostly
## driven by the sidecar's cloth chains), not by material or surface name.

const SHOT_EVERY := 3
## Frames to let every exponential smoother settle before measuring anything.
const WARMUP := 120
## Shots taken. A whole run cycle rather than a handful of samples of it:
## the capture is not locked to the simulation step, so a few samples land on
## a different phase every run and the total swings 2-3x. Averaged over the
## full cycle that phase noise cancels and the number is comparable again.
const SHOTS := 40
## The movement states the skirt has to survive, one per shot pair. Running is
## where the defect was first seen, but a jump and a slide put the thigh through
## the front of the skirt in poses a run never reaches.
const STATES := [["ground", 9.0], ["ground", 3.0], ["air", 6.0], ["air", -8.0],
	["slide", 10.0], ["dash", 14.0], ["ground", 9.0], ["air", 6.0]]

var _frames := 0
var _out := "."
var _model: SkinnedPlayerModel = null
var _cam: Camera3D = null
var _shots := 0
var _painted := false
## [MeshInstance3D, surface, body material] for every non-cloth surface, so the
## body can be blanked for the cloth-only frame and put back.
var _body: Array = []
var _blank: Material = null
var _grey: Material = null


func _initialize() -> void:
	var args := OS.get_cmdline_user_args()
	_out = args[0] if args.size() > 0 else "."
	var path := "res://assets/characters/skins/taila.glb"
	if args.size() > 1:
		path = "res://assets/characters/skins/%s.glb" % args[1]
	var scene := Node3D.new()
	root.add_child(scene)
	current_scene = scene

	var env := WorldEnvironment.new()
	var e := Environment.new()
	e.background_mode = Environment.BG_COLOR
	e.background_color = Color(0.05, 0.05, 0.08)
	e.ambient_light_source = Environment.AMBIENT_SOURCE_COLOR
	e.ambient_light_color = Color(1, 1, 1)
	e.ambient_light_energy = 1.0
	env.environment = e
	scene.add_child(env)

	_model = SkinnedPlayerModel.new()
	_model.model_path = path
	scene.add_child(_model)
	_cam = Camera3D.new()
	_cam.fov = 30.0
	scene.add_child(_cam)
	_cam.current = true


## Flat unshaded colours: magenta for anything the cloth chains drive, grey for
## the rest. Overrides, so the character's own toon materials are untouched.
func _paint(skel: Skeleton3D) -> void:
	var cloth := {}
	var side: String = _model.model_path.get_basename() + ".rig.json"
	var info = JSON.parse_string(FileAccess.get_file_as_string(side))
	if typeof(info) == TYPE_DICTIONARY:
		for c in info.get("chains", []):
			for n in c.get("bones", []):
				var i := skel.find_bone(String(n))
				if i >= 0:
					cloth[i] = true

	# Which bones are LIMBS, so their surfaces can be told from the torso.
	var limb := {}
	if typeof(info) == TYPE_DICTIONARY:
		for c in info.get("colliders", []):
			for key in ["bone", "child"]:
				var bn := String(c.get(key, ""))
				for b in skel.get_bone_count():
					var n := skel.get_bone_name(b)
					if n == bn or n.begins_with(bn + "."):
						limb[b] = true

	# DEPTH, written into the colour channel — not a flat tag colour.
	#
	# A silhouette test cannot answer this question. With the legs apart you see
	# the FAR side of the skirt through the gap between them, the thigh is
	# correctly in front of that, and a mask test counts every one of those
	# pixels: it reported 25% of the cloth covered on poses that are fine, and
	# sent two rounds of tuning after a defect that was not there. Comparing
	# distances instead, a leg only counts when it is nearer than the NEAREST
	# CLOTH at that pixel, which is exactly what "the thigh is showing through
	# the skirt" means.
	#
	# 0 stays "no geometry here", so real depths start just above it.
	var sh := Shader.new()
	# The cloth pass culls BACK FACES, so only the NEAR surface of the garment is
	# drawn. Without that the far side of the skirt — what you see through the gap
	# between the legs — is in the mask too, the thigh is correctly in front of it,
	# and every one of those pixels reads as a defect.
	sh.code = "shader_type spatial;
" 		+ "render_mode unshaded, cull_back;
" 		+ "varying float view_z;
" 		+ "void vertex() { view_z = -(MODELVIEW_MATRIX * vec4(VERTEX, 1.0)).z; }
" 		+ "void fragment() {
" 		+ "  float d = clamp((view_z - 0.4) / 1.6, 0.0, 0.96);
" 		+ "  ALBEDO = vec3(0.02 + d);
" 		+ "}
"
	var mag := ShaderMaterial.new()
	mag.shader = sh
	var sh_body := Shader.new()
	sh_body.code = sh.code.replace("cull_back", "cull_disabled")
	var body_mat := ShaderMaterial.new()
	body_mat.shader = sh_body
	var cyan := body_mat
	_grey = body_mat
	var grey := body_mat

	for mi in _model.find_children("*", "MeshInstance3D", true, false):
		if mi.mesh == null:
			continue
		if mi.skin == null:
			# The model's own outline shell has no skin and would hide
			# everything behind it.
			mi.visible = false
			continue
		var skin: Skin = mi.skin
		var bone_of := {}
		for b in skin.get_bind_count():
			var bi := skin.get_bind_bone(b)
			if bi < 0:
				bi = skel.find_bone(skin.get_bind_name(b))
			bone_of[b] = bi
		for s in range(mi.mesh.get_surface_count()):
			var arrays: Array = mi.mesh.surface_get_arrays(s)
			var verts: PackedVector3Array = arrays[Mesh.ARRAY_VERTEX]
			var bones: PackedInt32Array = arrays[Mesh.ARRAY_BONES]
			var weights: PackedFloat32Array = arrays[Mesh.ARRAY_WEIGHTS]
			var is_cloth := false
			var is_limb := false
			if not bones.is_empty() and not verts.is_empty():
				var per: int = bones.size() / verts.size()
				var n := 0
				var legn := 0
				for v in verts.size():
					# The SUM of the cloth chains' share, not the single
					# heaviest bone. tools/retarget.py's bind_cloth_to_legs
					# hands cloth vertices resting on a thigh most of their
					# weight, so on the panels that matter here the dominant
					# bone is the LEG and a heaviest-bone test calls the whole
					# skirt body.
					var w := 0.0
					for k in per:
						if cloth.has(bone_of[bones[v * per + k]]):
							w += weights[v * per + k]
					if w > 0.25:
						n += 1
					var lw := 0.0
					for k in per:
						if limb.has(bone_of[bones[v * per + k]]):
							lw += weights[v * per + k]
					if lw > 0.5:
						legn += 1
				is_cloth = n * 4 > verts.size()
				is_limb = not is_cloth and legn * 2 > verts.size()
			var mat: Material = grey
			if is_cloth:
				mat = mag
			elif is_limb:
				mat = cyan
			mi.set_surface_override_material(s, mat)
			if not is_cloth:
				_body.append([mi, s, mat])
			print("   %s/%d  %s" % [mi.name, s,
				"CLOTH" if is_cloth else ("LIMB" if is_limb else "body")])
	_blank = StandardMaterial3D.new()
	_blank.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
	_blank.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
	_blank.albedo_color = Color(0, 0, 0, 0)
	_blank.no_depth_test = false
	_blank.depth_draw_mode = BaseMaterial3D.DEPTH_DRAW_DISABLED
	print("painted %d cloth bones' surfaces magenta" % cloth.size())


## Screen row of the hip joint, so the measurement can ignore the torso.
func _write_hip_row() -> void:
	var skel: Skeleton3D = _model.skeleton
	var h := skel.find_bone("DEF-thigh.L")
	if h < 0:
		h = skel.find_bone("DEF-spine")
	if h < 0:
		return
	var world: Vector3 = skel.global_transform * skel.get_bone_global_pose(h).origin
	var f := FileAccess.open("%s/hip_%d.txt" % [_out, _shots], FileAccess.WRITE)
	if f:
		f.store_string("%d" % int(_cam.unproject_position(world).y))
		f.close()


## Drive the animation and the solver on a FIXED timestep.
##
## Both advance on the real frame delta otherwise, so the pose at a given frame
## drifts between runs and the same build measured 146k and 398k offending
## pixels. Every A/B comparison made without this was noise, and several tuning
## decisions were taken on the strength of it.
##
## The modifier stack needs pinning too: on PHYSICS it runs a variable number
## of times per rendered frame, so with a fixed step the amount of simulated
## time per frame still wandered.
func _lock_timestep() -> void:
	var skel: Skeleton3D = _model.skeleton
	if skel:
		skel.modifier_callback_mode_process = \
			Skeleton3D.MODIFIER_CALLBACK_MODE_PROCESS_IDLE
		var spring := skel.get_node_or_null("SpringBones")
		if spring:
			spring.fixed_delta = STEP
	for n in _model.find_children("*", "AnimationTree", true, false):
		n.callback_mode_process = AnimationMixer.ANIMATION_CALLBACK_MODE_PROCESS_MANUAL


## One fixed step of the animation. Call once per rendered frame.
func _step_anim() -> void:
	for n in _model.find_children("*", "AnimationTree", true, false):
		n.advance(STEP)

func _process(_delta: float) -> bool:
	_frames += 1
	if _frames < 10 or not _model.loaded:
		return false
	if not _painted:
		if _model.skeleton == null:
			return true
		# Fixed timestep, or nothing here is repeatable: the solver integrates
		# against the real frame delta, so the same build measured 93k and 76k
		# offending pixels on consecutive runs and every A/B comparison was noise.
		_lock_timestep()
		_paint(_model.skeleton)
		_painted = true
		return false
	var st: Array = STATES[clampi(_shots * STATES.size() / SHOTS, 0, STATES.size() - 1)]
	_model.update_state(st[0], st[1], false)
	_model.set_locomotion(0.0, 1.0, 0.0)
	_step_anim()

	var hips := 0.95
	if _model.skeleton:
		var h := _model.skeleton.find_bone("DEF-spine")
		if h >= 0:
			hips = _model.skeleton.get_bone_global_pose(h).origin.y
	# Level with the hem and dead in front: the view a player actually gets.
	# Long warm-up before the first shot. The pose layer's lean/hold smoothers
	# still run on the real frame delta and only converge exponentially, so
	# sampling early made the run irreproducible however tightly the solver and
	# the animation were pinned.
	if _frames > WARMUP and _shots < SHOTS:
		var phase := _frames % SHOT_EVERY
		if phase == 0:
	# NEGATIVE Z is the FRONT. SkinnedPlayerModel spins the imported scene 180
	# degrees (`facing_flip`: glTF forward is +Z, players face -Z), so a camera
	# on +Z looks at the character's BACK. Every tool in here used to sit on +Z,
	# and every "front" judgement made from them was of the back of the skirt.
			_cam.position = Vector3(0.0, hips - 0.10, -0.95)
			_cam.look_at(Vector3(0, hips - 0.14, 0), Vector3.UP)
		elif phase == 1:
			root.get_texture().get_image().save_png(
				"%s/clipview_%d.png" % [_out, _shots])
			for e in _body:
				e[0].set_surface_override_material(e[1], _blank)
		elif phase == 2:
			# Same pose, one frame later — near enough to read the coverage.
			root.get_texture().get_image().save_png(
				"%s/cloth_%d.png" % [_out, _shots])
			_write_hip_row()
			for e in _body:
				e[0].set_surface_override_material(e[1], e[2])
			print("saved clipview_%d (%s %.0f) + cloth_%d" % [
				_shots, st[0], st[1], _shots])
			_shots += 1
	if _shots >= SHOTS or _frames > WARMUP + SHOTS * SHOT_EVERY + 40:
		return true
	return false