viewof animation = md`<input type=checkbox>`
/*
* Buckminster Fuller’s spherical triangle transformation procedure
*
* Based on Robert W. Gray’s formulae published in “Exact Transformation Equations
* For Fuller's World Map,” _Cartographica_, 32(3): 17-25 (1995).
*
* Implemented for D3.js by Philippe Rivière, 2018 (https://visionscarto.net/)
*
* To the extent possible under law, Philippe Rivière has waived all copyright
* and related or neighboring rights to this implementation. (Public Domain.)
*/
function GrayFullerRaw() {
// standard symbols
var sqrt = Math.sqrt,
cos = Math.cos,
sin = Math.sin,
atan2 = Math.atan2,
SQRT_3 = sqrt(3.);
// Gray’s constants
var Z = sqrt(5. + 2. * sqrt(5.)) / sqrt(15.),
el = sqrt(8.) / sqrt(5. + sqrt(5.)),
dve = sqrt(3. + sqrt(5.)) / sqrt(5. + sqrt(5.));
return function(lambda, phi) {
var cosPhi = cos(phi),
s = Z / (cosPhi * cos(lambda)),
x = cosPhi * sin(-lambda) * s,
y = sin(phi) * s,
a1p = atan2(2. * y / SQRT_3 + el / 3. - el / 2., dve),
a2p = atan2(x - y / SQRT_3 + el / 3. - el / 2., dve),
a3p = atan2(el / 3. - x - y / SQRT_3 - el / 2., dve);
return [SQRT_3 * (a2p - a3p), 2. * a1p - a2p - a3p];
};
}
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
