cutan.carve.parts

Split a carved prop into moving parts, each with a declared pivot.

A clock’s hands come off its face, a camera into tripod, body and lens: each part is lifted out of a Carving by a mask, gets a pivot (the point it turns about), and the base keeps what is left. Where a part lay inside the base (a hand on the face), the base is painted in under it from the surrounding pixels, so the part can move without leaving a hole; where it stuck out (a lens past the body), the base simply loses it.

Masks and pivots are in the SOURCE image’s pixels, like every other coordinate cutan.carve takes, so a part spec can be written before the carve runs (the carving’s trim decides its own pixels). A mask may also be an array of the carving’s size.

>>> import numpy as np
>>> from cutan.carve import carve
>>> img = np.full((40, 60, 3), 250, np.uint8); img[10:30, 10:50] = (200, 40, 40)
>>> img[18:22, 30:46] = (40, 40, 200)                        # a blue hand on a red face
>>> face = carve(img, point=(20, 20))
>>> split = split_parts(face, {"hand": PartSpec(mask=[(29, 17), (47, 17), (47, 23), (29, 23)],
...                                             pivot=(30, 20))})
>>> hand = split.parts[0]
>>> (hand.origin[0] + hand.pivot[0], hand.origin[1] + hand.pivot[1]) == face.to_part([(30, 20)])[0]
True
>>> tuple(int(v) for v in np.asarray(split.base)[10, 35])   # painted in under the hand, opaque
(200, 40, 40, 255)

Functions

split_parts(carving, parts, *[, paint_out, ...])

Lift parts ({name: PartSpec}, in draw order) off carving.

Classes

Part(name, image, pivot, origin, draw_order)	One lifted part: its RGBA image, its pivot in that image, where it sits in the carving.
PartSet(carving, base[, parts])	A carving split into a base (None when every pixel went to a part) and parts.
PartSpec(mask, pivot[, grow, reach])	What to lift off a carving: a mask and the pivot it turns about.

class cutan.carve.parts.Part(name, image, pivot, origin, draw_order)

Bases: object

One lifted part: its RGBA image, its pivot in that image, where it sits in the carving.

property anchor: tuple[float, float]

The pivot as an attachment anchor (0..1 of the image).

class cutan.carve.parts.PartSet(carving, base, parts=list())

Bases: object

A carving split into a base (None when every pixel went to a part) and parts.

class cutan.carve.parts.PartSpec(mask, pivot, grow=1, reach=None)

Bases: object

What to lift off a carving: a mask and the pivot it turns about.

mask: a polygon [(x, y), ...] in source pixels, a matte called on the carving’s RGB with the carving’s frame as its hint (so a matte’s own coordinates are source pixels too; ~FlatColour(colours=[grey], connected=False) selects the grey strokes), or an array of the carving’s size (bool or 0..1). pivot: (x, y) in source pixels. grow: carving px the mask is widened by before lifting (anti-aliased strokes). reach: keep only the mask’s pieces that come within this many source px of the pivot (a colour key also matches specks elsewhere: a tick’s grey edge).

cutan.carve.parts.split_parts(carving, parts, *, paint_out=True, inpaint_radius=4, pad=2)

Lift parts ({name: PartSpec}, in draw order) off carving.

Each part takes the carving’s pixels under its mask. Parts are drawn in the order listed, the last on top, and the one drawn on top owns a pixel two masks share (a clock’s hub cap, listed after the hands, keeps the hub). The base keeps the rest, and stays opaque under a part’s soft edge (no seam at rest); where a part was enclosed by the base, paint_out re-paints the base under it (cv2.inpaint) so it stays whole when the part moves. A part’s origin and pivot are in the carving’s pixels (where write_prop() places it).

Return type:

PartSet