194 lines
5.6 KiB
GDScript
194 lines
5.6 KiB
GDScript
class_name FacePainter
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extends Node
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## 面部画笔：直接往一张 Image 的字节缓冲上盖笔刷印章。
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##
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## 为什么不用 Control._draw()：Godot 4 的 canvas 已经没有「擦除」混合模式了
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## （CanvasItemMaterial 只有 mix / add / sub / mul / premult，也没有 draw_set_blend_mode），
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## 橡皮没法靠 blend_mode 实现。自己管像素反而更直接：
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## 画 = 标准的 source-over alpha 混合；擦 = 把目标的 alpha 乘掉；存档 = 就是存这张图。
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var image: Image
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var texture: ImageTexture
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var canvas_size: int = 512
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## 当前笔刷。绘画面板改这几个值，下一笔生效。
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var brush_color: Color = Color.BLACK
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var brush_width: float = 12.0
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var erasing: bool = false
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## 像素缓冲（RGBA8）。所有绘制都改它，一笔画完再一次性推给显卡。
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var _buf: PackedByteArray
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## 圆形笔刷的覆盖度，边长 _stamp_d
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var _cov: PackedFloat32Array
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var _stamp_d: int = 0
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var _stamp_rgb: Vector3 = Vector3.ZERO
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var _last_stamp: Vector2 = Vector2.INF
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func _init(size: int = 512) -> void:
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canvas_size = size
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func _ready() -> void:
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_buf = PackedByteArray()
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_buf.resize(canvas_size * canvas_size * 4)
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_sync()
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# ---------------- 画笔接口 ----------------
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func begin_stroke(pos: Vector2) -> void:
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_rebuild_stamp()
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_last_stamp = Vector2.INF
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_stamp_at(pos)
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_last_stamp = pos
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_sync()
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func extend_stroke(pos: Vector2) -> void:
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if not _last_stamp.is_finite():
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_stamp_at(pos)
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_last_stamp = pos
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_sync()
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return
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var spacing := maxf(1.0, brush_width * 0.25)
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var dist := _last_stamp.distance_to(pos)
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if dist < spacing:
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return
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# 鼠标动得快时两点之间得补章，否则线是一串断点
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var steps := int(ceil(dist / spacing))
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for i in range(1, steps + 1):
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_stamp_at(_last_stamp.lerp(pos, float(i) / float(steps)))
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_last_stamp = pos
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_sync()
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func end_stroke() -> void:
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_last_stamp = Vector2.INF
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func clear() -> void:
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_buf.fill(0)
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_last_stamp = Vector2.INF
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_sync()
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## 拍一张当前笔画层的快照。绘画面板打开时存一份，点「取消」时还原
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func snapshot() -> PackedByteArray:
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return _buf.duplicate()
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## 还原到快照。尺寸对不上就忽略（换过画布大小）
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func restore(data: PackedByteArray) -> void:
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if data.size() != _buf.size():
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return
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_buf = data.duplicate()
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_last_stamp = Vector2.INF
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_sync()
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# ---------------- 存档 ----------------
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## 笔画层存成一张透明底 PNG
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func save_png(path: String) -> void:
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_sync()
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image.save_png(path)
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## 读回笔画层。尺寸对不上就当没读到（换了画布大小的话）
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func load_png(path: String) -> void:
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if not FileAccess.file_exists(path):
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return
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set_image(Image.load_from_file(path))
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## 从一张 Image 直接载入笔画层 —— 联机收到别人的脸时走这条，不用落盘
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func set_image(img: Image) -> void:
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if img == null:
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return
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if img.get_width() != canvas_size or img.get_height() != canvas_size:
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push_warning("笔画层尺寸是 %s，画布是 %d，忽略" % [img.get_size(), canvas_size])
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return
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img.convert(Image.FORMAT_RGBA8)
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_buf = img.get_data()
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_last_stamp = Vector2.INF
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_sync()
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## 当前笔画层的 PNG 字节 —— 联机同步用，不落盘
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func to_png_bytes() -> PackedByteArray:
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_sync()
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return image.save_png_to_buffer()
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# ---------------- 内部 ----------------
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## 把字节缓冲变成 Image 再推给显卡。一笔画完调一次 —— 512² 一次就是 1MB，别每盖一个印章都来
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func _sync() -> void:
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image = Image.create_from_data(canvas_size, canvas_size, false, Image.FORMAT_RGBA8, _buf)
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if texture == null:
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texture = ImageTexture.create_from_image(image)
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else:
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texture.update(image)
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## 按当前粗细和颜色重造笔刷。边缘留 1 像素羽化 —— 硬边的线很难看。
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func _rebuild_stamp() -> void:
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var r := maxi(2, int(round(brush_width * 0.5)))
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var d := r * 2
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_stamp_d = d
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_stamp_rgb = Vector3(brush_color.r, brush_color.g, brush_color.b)
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_cov.resize(d * d)
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for y in d:
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for x in d:
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var dx := float(x) - float(r) + 0.5
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var dy := float(y) - float(r) + 0.5
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var dist := sqrt(dx * dx + dy * dy) / float(r)
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_cov[y * d + x] = clampf((1.0 - dist) * float(r), 0.0, 1.0)
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## 在 pos 处盖一个印章。越界像素直接跳过，所以画到边上也不会出错。
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func _stamp_at(pos: Vector2) -> void:
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var d := _stamp_d
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# d 恒为偶数（上方是按 r * 2 算出来的），这里的整除不会丢精度。
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# 所以只抑制警告、不改算法 —— 换成浮点反而会引入半像素偏移。
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@warning_ignore("integer_division")
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var r := d / 2
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var cx := int(round(pos.x)) - r
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var cy := int(round(pos.y)) - r
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var sr := _stamp_rgb.x * 255.0
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var sg := _stamp_rgb.y * 255.0
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var sb := _stamp_rgb.z * 255.0
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for sy in d:
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var ty := cy + sy
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if ty < 0 or ty >= canvas_size:
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continue
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var row := ty * canvas_size * 4
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var srow := sy * d
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for sx in d:
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var tx := cx + sx
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if tx < 0 or tx >= canvas_size:
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continue
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var cov := _cov[srow + sx]
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if cov <= 0.001:
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continue
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var o := row + tx * 4
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if erasing:
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# 擦：把 alpha 按覆盖度乘掉。RGB 留着不管 —— shader 只看 alpha
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_buf[o + 3] = int(float(_buf[o + 3]) * (1.0 - cov))
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continue
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var sa := cov
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var da := float(_buf[o + 3]) / 255.0
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var na := sa + da * (1.0 - sa)
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if na <= 0.0001:
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continue
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var ws := sa / na
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var wd := da * (1.0 - sa) / na
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_buf[o] = int(clampf(sr * ws + float(_buf[o]) * wd, 0.0, 255.0))
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_buf[o + 1] = int(clampf(sg * ws + float(_buf[o + 1]) * wd, 0.0, 255.0))
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_buf[o + 2] = int(clampf(sb * ws + float(_buf[o + 2]) * wd, 0.0, 255.0))
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_buf[o + 3] = int(clampf(na * 255.0, 0.0, 255.0))
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