book-mockup

Renders a photographic mockup of an upright book from flat artwork: front cover, spine and (optionally) back cover. The book can be turned to any angle through 360°, viewed from any height, and is lit consistently with a soft floor shadow. Everything is done in one GEGL graph.

Install

With Homebrew, from the companion tap:

brew install rogerfarrell/tap/book-mockup

From source (needs GEGL 0.4 and pkg-config/pkgconf):

make
make install PREFIX="$HOME/.local"   # or sudo make install

Usage

book-mockup -c cover.png -s spine.png -k back.png -o mockup.png

Common variations:

book-mockup -c cover.png -s spine.png -a 155 -k back.png  # back view
book-mockup -c cover.png -s spine.png -e 1.4               # look down on the pages
book-mockup -c cover.png -s spine.png -g none              # transparent PNG

Cover and spine should come from the same cover wrap at the same resolution: the book's thickness is taken from the spine image's width relative to the cover's height.

Artwork and textures can be PNG, JPEG, TIFF or WebP (chosen by file extension, case-insensitive).

Options

Option	Meaning	Default
-c, --cover=FILE	Front cover image	required
-s, --spine=FILE	Spine image	required
-k, --back=FILE	Back cover image	plain board
-o, --output=FILE	Output file; format follows the extension	mockup.png
-a, --angle=DEG	Rotation: 0 front, 90 spine, 180 back, 155 back with spine	25
-p, --perspective=N	Perspective strength; larger exaggerates the near side, 0 is flat	0.3
-W, --width=PX	Canvas width	2400
-H, --height=PX	Canvas height	2400
-b, --book-height=PX	Book height on the canvas	1800
-e, --camera-height=N	Eye height above the floor, × book height; above 1 shows the top	0.5
-g, --background=COLOR	Background color, or none for transparent	white
--shadow-direction=DEG	Shadow direction from straight back, + is left	40
--shadow-length=N	Shadow length, × book height	0.55
--shadow-opacity=N	Cast shadow opacity	0.55
--page-lines=N	Strength of page-edge lines (0 disables)	0.18
--page-grain=N	Strength of paper grain on the pages (0 disables)	0.05
-t, --texture=FILE	Texture image for the cover stock (covers and spine)	none
--texture-strength=N	Strength of --texture	0.15
--cover-grain=N	Noise grain on covers and spine	0
--seed=N	Base seed for generated noise; output is reproducible	1
--crease=N	Depth of the hinge creases (0 disables)	0.35
--crease-offset=N	Crease distance from the spine, × book height	0.03
--crease-width=N	Crease width, × book height	0.006

Notes

• Transparent output. With -g none the shadow is pure #000000 with varying alpha, so it composites cleanly onto any background. Rendering on white and removing the white later leaves a gray shadow; use -g none for assets that will sit on other backgrounds.
• Perspective strength is the book height divided by the camera's distance, so the same value gives the same view at any --book-height. 0.3 is a natural product shot; 0.6 or more looks like a close, wide-angle photo.
• The camera aims at the book. With --camera-height above or below mid-book, the camera tilts toward the book's middle, so vertical edges converge as in a real photo taken from above. It also zooms so the nearest vertical edge stays at --book-height. At --perspective 0 the camera is infinitely far away, so its height has no effect.
• Linear light. Shading and textures work in linear light, as GEGL does internally, so strengths read a little lighter than the same numbers would in an sRGB editor.

Code layout

book-mockup.c is a single file organized in four strata, each depending only on those above it, so a leading portion can be reused in another project:

1. Math — points, quads, homographies, convex hulls.
2. Scene — pinhole camera, textured faces, a rotating six-sided box, lighting and the floor shadow.
3. Render — generic GEGL graph builders.
4. App — the book itself: options, command line and main().

Strata 1–3 know nothing about books; another box-shaped product needs only a new stratum 4. Sections are separated by page breaks (C-x ] and C-x [ in Emacs).

License

GPL-3.0-or-later. See COPYING.