Sylpheed/port/scripts/screen_view.gd

# Draws one exported screen, either at a moment on its timeline or at the
# `rest` pose the export declares.
#
# TIMELINE is the real behaviour and the default. A keyframe is the start of a
# LINEAR ramp toward the next, and the unit of `t` comes from
# `authored/timing.json` -- it is measured, not on the disc, which is why it is
# authored and applied in exactly one place.
#
# REST reproduces what the export's `rest` field says, which is what
# `sylpheed-cli screen render` draws. It is kept so `tools/verify-screen` can
# hold both renderers to the same assumption. The two modes DISAGREE on six
# elements in this export, and the running game sides with the timeline -- see
# `docs/DECISIONS.md`.
#
# One CanvasItem draws the whole screen in `_draw`, rather than a node per
# element. The export's `paint_order` is already back-to-front, so honouring it
# is a loop; z-indexing sixteen nodes to reproduce the same order would be the
# same information expressed less directly, and would hide a tie behind Godot's
# own sibling rules.
class_name ScreenView
extends Node2D

## Skip `kind & 0x4` template instances that duplicate a plain element.
## docs/FORMAT.md: those are motion-trail ghosts and are not on screen at rest.
## The narrow form of the rule matters -- 174 elements on the disc carry the bit
## with no template to duplicate, and a blanket skip would erase them.
const KIND_TEMPLATE_INSTANCE := 0x4

enum Pose { TIMELINE, REST }

## Which pose to draw. TIMELINE walks the keyframes at `time_units`; REST draws
## the export's declared `rest` and is there for renderer-vs-renderer diffing.
var pose_mode: Pose = Pose.TIMELINE

## Position on the timeline, in the disc's own keyframe units. `t` is left raw
## everywhere; seconds appear only where `units_per_second` is applied.
var time_units: float = 0.0
var units_per_second: float = 60.0

var tree: ExportTree = null
var screen: Dictionary = {}
var textures: Dictionary = {}
var skipped: Array[String] = []
var drawn: Array[String] = []

## Which button is highlighted, by element id. P1 leaves it empty: initial focus
## was measured as unstable boot to boot (HANDOFF Q5) and picking one is an
## authored decision that belongs to P5.
var focused_id: String = ""


func load_screen(t: ExportTree, name: String) -> bool:
	tree = t
	screen = t.screen(name)
	if screen.is_empty():
		push_error(t.error)
		return false
	var design: Array = screen.get("design", [1280, 720])
	# The export's coordinates are in this space and the viewport matches it, so
	# a mismatch means the export is not what this project was built to draw.
	var viewport := Vector2i(
		ProjectSettings.get_setting("display/window/size/viewport_width"),
		ProjectSettings.get_setting("display/window/size/viewport_height"))
	if Vector2i(int(design[0]), int(design[1])) != viewport:
		push_warning("screen %s is authored at %sx%s, viewport is %s" % [name, design[0], design[1], viewport])
	_load_textures()
	queue_redraw()
	return true


func _load_textures() -> void:
	textures.clear()
	for element: Dictionary in screen.get("elements", []):
		for key in ["sprite", "focus_sprite"]:
			var rel: String = element.get(key, "")
			if rel != "" and not textures.has(rel):
				var tex := tree.texture(rel)
				if tex == null:
					push_warning(tree.error)
				else:
					textures[rel] = tex


# `tint_rgba` is RGBA and `fade_argb` is ARGB -- different byte orders, on
# purpose, because the disc spells them differently and a silent swap looks like
# an art bug rather than a parse bug. They multiply per channel.
static func modulate_of(pose: Dictionary) -> Color:
	var tint := _rgba(pose.get("tint_rgba", "0xffffffff"))
	var fade := _argb(pose.get("fade_argb", "0xffffffff"))
	return Color(tint.r * fade.r, tint.g * fade.g, tint.b * fade.b, tint.a * fade.a)


static func _rgba(hex: String) -> Color:
	var v := hex.hex_to_int()
	return Color8((v >> 24) & 0xff, (v >> 16) & 0xff, (v >> 8) & 0xff, v & 0xff)


static func _argb(hex: String) -> Color:
	var v := hex.hex_to_int()
	return Color8((v >> 16) & 0xff, (v >> 8) & 0xff, v & 0xff, (v >> 24) & 0xff)


## The drawn rectangle of an element at a pose.
##
## `pos` is the top-left at 1:1 and `pivot` is the anchor scale grows about, so
## the top-left moves by `-pivot*(s-1)` and the size is the natural size times
## `s`. At 100 % the pivot cancels, which is why it can be got wrong invisibly.
static func placement(pose: Dictionary, pivot: Vector2, natural: Vector2) -> Rect2:
	var pos := _vec(pose.get("pos", [0, 0]))
	var s := _vec(pose.get("scale", [100, 100])) / 100.0
	return Rect2(pos - pivot * (s - Vector2.ONE), natural * s)


static func _vec(a: Array) -> Vector2:
	return Vector2(float(a[0]), float(a[1]))


## The pose of one element at `time_units`.
##
## The timed keyframes are the whole timeline. Before the first, the element
## holds its first pose (the pre-roll a staggered menu needs -- the five buttons
## start at t=28,30,32,34,36). After the last TIMED keyframe it holds that pose.
##
## It never plays into the final, untimed keyframe. That frame is the screen's
## EXIT pose, and the disc gives no time slot for the ramp into it, so playing
## it would mean inventing a duration. The exit is the transition, and it is
## P3's, with its own measured evidence. See `authored/timing.json`.
func pose_at(element: Dictionary, t: float) -> Dictionary:
	var frames: Array = element.get("keyframes", [])
	var timed: Array = []
	for k: Dictionary in frames:
		if k.has("t"):
			timed.append(k)
	if timed.is_empty():
		# No timed frame at all: the group is a single static pose.
		return frames[0] if not frames.is_empty() else element.get("rest", {})
	if t <= float(timed[0]["t"]):
		return timed[0]
	for i in range(timed.size() - 1):
		var a: Dictionary = timed[i]
		var b: Dictionary = timed[i + 1]
		var t0 := float(a["t"])
		var t1 := float(b["t"])
		if t < t1:
			# A keyframe is the start of a ramp toward the next, and the ramp is
			# linear -- measured, `authored/timing.json`.
			return _lerp_pose(a, b, 0.0 if t1 <= t0 else (t - t0) / (t1 - t0))
	return timed[timed.size() - 1]


# Channels are integers on the disc. The running game's own fade lands on
# `round(255*k/15)`, so rounding -- not truncation -- is what was measured.
static func _lerp_pose(a: Dictionary, b: Dictionary, f: float) -> Dictionary:
	return {
		"pos": [_ilerp(a["pos"][0], b["pos"][0], f), _ilerp(a["pos"][1], b["pos"][1], f)],
		"scale": [_ilerp(a["scale"][0], b["scale"][0], f), _ilerp(a["scale"][1], b["scale"][1], f)],
		"tint_rgba": _hex_lerp(a["tint_rgba"], b["tint_rgba"], f),
		"fade_argb": _hex_lerp(a["fade_argb"], b["fade_argb"], f),
	}


static func _ilerp(a: float, b: float, f: float) -> int:
	return int(round(a + (b - a) * f))


# Byte-wise, so it works for both orders without knowing which one it has.
static func _hex_lerp(a: String, b: String, f: float) -> String:
	var x := a.hex_to_int()
	var y := b.hex_to_int()
	var out := 0
	for shift in [24, 16, 8, 0]:
		out |= (_ilerp((x >> shift) & 0xff, (y >> shift) & 0xff, f) & 0xff) << shift
	return "0x%08x" % out


## The last moment anything on this screen is still moving, in keyframe units.
func settle_time() -> float:
	var last := 0.0
	for element: Dictionary in screen.get("elements", []):
		for k: Dictionary in element.get("keyframes", []):
			if k.has("t"):
				last = maxf(last, float(k["t"]))
	return last


# An element is a ghost only when another element on the same screen carries the
# same id *without* the template bit -- the template it is a repeat of.
func _template_instance_ids() -> Dictionary:
	var plain := {}
	for element: Dictionary in screen.get("elements", []):
		if int(String(element.get("kind_raw", "0x0")).hex_to_int()) & KIND_TEMPLATE_INSTANCE == 0:
			plain[element.get("id", "")] = true
	var ghosts := {}
	for element: Dictionary in screen.get("elements", []):
		var kind := int(String(element.get("kind_raw", "0x0")).hex_to_int())
		if kind & KIND_TEMPLATE_INSTANCE != 0 and plain.has(element.get("id", "")):
			ghosts[int(element.get("index", -1))] = true
	return ghosts


func _draw() -> void:
	if screen.is_empty():
		return
	var elements: Array = screen.get("elements", [])
	var ghosts := _template_instance_ids()
	skipped.clear()
	drawn.clear()
	for index: int in screen.get("paint_order", []):
		var element: Dictionary = elements[index]
		var id: String = element.get("id", "")
		if ghosts.has(index):
			skipped.append("%s (template instance)" % id)
			continue
		var pose: Dictionary = element.get("rest", {}) if pose_mode == Pose.REST \
			else pose_at(element, time_units)
		var colour := modulate_of(pose)
		if colour.a <= 0.0:
			skipped.append("%s (transparent at rest)" % id)
			continue
		var pivot := _vec(element.get("pivot", [0, 0]))
		var rel: String = element.get("sprite", "")
		if focused_id == id and element.get("focus_sprite", "") != "":
			rel = element["focus_sprite"]
		if rel != "":
			var tex: Texture2D = textures.get(rel)
			if tex == null:
				skipped.append("%s (sprite failed to load)" % id)
				continue
			draw_texture_rect(tex, placement(pose, pivot, tex.get_size()), false, colour)
			drawn.append(id)
		elif element.get("role", "") == "primitive" and element.has("size"):
			# A primitive has no texture; the quad is its declared size and its
			# colour is the pose's own modulate.
			draw_rect(placement(pose, pivot, _vec(element["size"])), colour, true)
			drawn.append(id)
		else:
			# A .t32 element whose sprite the exporter could not produce. Saying
			# so is the point -- a silently missing element looks like art.
			skipped.append("%s (no sprite in the export)" % id)