Proposal:Window:shape

window:shape
Proposal status:	Proposed (under way)
Proposed by:	b-unicycling
Tagging:	`window:shape=*`
Applies to:
Definition:	Defining the basic shape of a window for 3D rendering and general mapping.
Statistics:
Draft started:	2022-01-11
RFC start:	2022-01-12

Proposal

It is proposed to standardize the tagging of window shapes under the key window:shape=* and window:top:shape=* to avoid confusion with window:type=*.

Rationale

Windows are generically rendered as rectangles. However, churches, castles, temples etc often feature more elaborate shapes of windows. In the long run, it would be beneficial to have those windows rendered closer to what they look like in real life. Also, for users interested in architectural characteristics of a building, the window shape plays a role in the aesthetic.

Terms like "Gothic" or "Romanesque" should be avoided in favour of simple geometrical terms, because they are probably more user friendly. Also, these terms could fall under the architecture=* tag and a building with "Gothic" shape windows could be Neo-Gothic or Tudor revival.

As the taginfo for window:shape and window:top:shape shows, some shapes like rectangular, circle and semicircle are already in use. However, fewer cases have these characteristics tagged as window:type. This should be reserved for sashed windows or French windows etc.

Some of these shapes can also be applied with doors.

Tagging

For window shapes with rectangular bottom parts (also applies to doors)
Suggested tag	Synonyms	In use?
`window:top:shape=rectangle` (presumed as default)	square	no
`window:top:shape=semicircle`	Romanesque	yes
`window:top:shape=pointed`	Gothic	no
`window:top:shape=triangle`		no
`window:top:shape=ogee`	onion-shaped	no
`window:top:shape=double-ogee`	double-onion-shaped	no

Window shapes with non-rectangular bottom parts
Suggested tag	Synonyms	In use?
`diamond`		yes
`circle`	round	yes
`pentagon`	five-sided	no
`hexagon`	six-sided	no
`octagon`	eight-sided	no
`trefoil`	flower with 3 petals	no
`quatrefoil`	flower with 4 petals	no
`hexafoil`	flower with 6 petals	no
`octofoil`	flower with 8 petals	no
`dodecafoil`	flower with 12 petals	no

Examples

Rectangular windows at Brzeg Castle
Circular window at the Church of Holy Name in Okříšky
Circular window at St Anne's in Aigburth
Diamond shaped window
Semi-circular(Romanesque) windows at the church Saint-Aubin de Boisney (Eure, France)
Pointed (Gothic) window
Remains of a double-ogee window in a castle ruin in Co. Kilkenny, Ireland
Pentagonal window at St Giles, Sheldon
Irregular pentagonal window
Hexgonal window in Joensuu, Finland
Octagonal window in Brighton, England
Trefoil windows at High Beach, Sussex, England
Quatrefoil window at Upper Sheringham
Octafoil window in a church
Combination of hexafoil and trefoil windows at a Wesleyan chapel