Published
Edited
Jul 7, 2021
3 forks
9 stars
Rectangular Polyconic GLSLSatellite GLSLVan Der Grinten IV GLSLVan Der Grinten III GLSLVan Der Grinten II GLSLWinkel Tripel GLSLLee Modified Stereographic GLSLMiller Oblated Stereographic GLSLModified Stereographic GS48 GLSLModified Stereographic GS50 GLSLFoucaut GLSLLagrange GLSLKavrayskiy VII GLSLEisenlohr GLSLEckert VI GLSLEckert V GLSLEckert IV GLSLEckert III GLSLEckert II GLSLEckert I GLSLBertin1953 GLSLWagner VI GLSLPhytoplanktonBriesemeister GLSLRectilinear GLSLAzimuthal Equal-Area GLSLCordiform GLSLTransverse Mercator GLSLMercator GLSLMollweide GLSLAtlantis GLSLWiechel GLSLWagner VII GLSLTimes GLSLWagner IV GLSLEqual Earth GLSLConic Equal-Area GLSLAlbers GLSLEquirectangular GLSLConic Conformal GLSLConic Equidistant GLSLVan Der Grinten GLSLLittrow GLSLAzimuthal Equidistant GLSLArmadillo GLSLLarrivée GLSLCylindrical Equal-Area GLSLAitoff GLSLAiry GLSLAugust GLSLBerghaus GLSLBaker Transverse GLSLBaker GLSLBoggs GLSLBonne GLSLHammer GLSLBromley GLSLBottomley GLSLCollignon GLSLFahey GLSLTransverse Fahey GLSLLoximuthal GLSLCylindrical Stereographic GLSLCylindrical Equal-Area GLSLPolyconic GLSLPatterson GLSLMiller GLSLRobinson GLSL
WebMercator to globe
Also listed in…
Projections
projection = d3.geoOrthographic().rotate([-120, -30, 0])
import { zoom } from "@d3/versor-zooming"
maxTextureSize = {
const gl = document.createElement("canvas").getContext("webgl");
return gl.getParameter(gl.MAX_TEXTURE_SIZE);
}
image = d3.image(
"https://upload.wikimedia.org/wikipedia/commons/f/f7/Normal_Mercator_map_85deg.jpg",
{
crossOrigin: "anonymous"
}
)
// the image must be "power of 2" to use a mipmap
imageP2 = {
const w = Math.min(
maxTextureSize,
2 ** Math.ceil(Math.log(image.naturalWidth) / Math.log(2))
), // better upscale if possible
h = w / 1;
const context = DOM.context2d(w, h, 1);
context.drawImage(image, 0, 0, w, h);
return Object.assign(context.canvas, { style: "max-height: 100px;" });
}
function mapShader(projection, glsl, postprojection, footer) {
const pixelRatio = Math.min(1.5, devicePixelRatio);
const canvas = document.createElement("canvas");
canvas.width = Math.floor(width * pixelRatio);
canvas.height = Math.floor(height * pixelRatio);
canvas.style.width = `${width}px`;
canvas.style.height = `${height}px`;
const regl = createREGL({
canvas,
attributes: { antialias: false, preserveDrawingBuffer: true },
optionalExtensions: ['OES_standard_derivatives', 'EXT_shader_texture_lod']
});
const texture = regl.texture({
data: imageP2,
mipmap: "nice",
min: "linear mipmap linear",
mag: "linear",
wrapS: "repeat",
flipY: true
});
const draw = createDrawCommand(
regl,
projection,
glsl,
postprojection,
footer,
width,
height,
texture
);
return Object.assign(canvas, { regl, draw });
}
createREGL = require("regl")
createDrawCommand = (
regl,
projection,
proj,
postprojection,
footer,
width,
height,
texture
) =>
regl({
frag: fragmentShader(proj, postprojection, footer),
vert: vertexShader(),
attributes: {
position: [-4, 0, 0, -4, 4, 4]
},
count: 3,
uniforms: {
texture,
u_scale: () => projection.scale(),
u_angle: () => projection.angle(),
u_translate: () => {
// accounts for projection.center()
const r = projection.rotate(),
t = projection.rotate([0, 0])([0, 0]);
projection.rotate(r);
return t;
},
u_rotate: () => projection.rotate(),
u_size: () => [width, height]
},
depth: { enable: false }
})
fragmentShader = (projection, postprojection, footer) => `
#ifdef GL_EXT_shader_texture_lod
#extension GL_EXT_shader_texture_lod : enable
#endif
#ifdef GL_OES_standard_derivatives
#extension GL_OES_standard_derivatives : enable
#endif
precision highp float;
uniform sampler2D texture;
uniform vec3 u_rotate;
const float pi = 3.141592653589793;
const float halfPi = pi * 0.5;
const float tau = pi * 2.0;
const float radians = pi / 180.0;
const float degrees = 1.0 / radians;
varying vec2 p;
${applyRotation()}
void main(void) {
float x = p.x;
float y = p.y;
float lambda, phi;
bool transparent = false;
// inverse projection
${projection}
// rotate
applyRotation(u_rotate, lambda, phi);
// texture coordinates
vec2 t = vec2(fract(lambda / tau - 0.5), 0.5 + phi / pi);
#ifdef GL_OES_standard_derivatives
// avoid a mipmap seam by controlling the derivative of t.x
if (fwidth(t.x) > 0.25 && t.x < 0.5) t.x += 1.0;
#endif
${postprojection}
// read the textures
#ifdef GL_EXT_shader_texture_lod
float scale = 0.8 * cos(phi * 0.97);
gl_FragColor = texture2DGradEXT(texture, vec2(t.x, t.y * 0.996 + 0.002), dFdx(t) * scale, dFdy(t) * scale);
#else
gl_FragColor = texture2D(texture, t);
#endif
if (transparent) gl_FragColor.a = 0.0;
${footer || "// no footer"}
}
`
vertexShader = () => `
precision highp float;
uniform float u_scale;
uniform float u_angle;
uniform vec2 u_translate;
uniform vec2 u_size;
attribute vec2 position;
varying vec2 p;
vec2 rotate2d(vec2 p, float a) {
float s = sin(a), c = cos(a);
return mat2(c, -s, s, c) * p;
}
void main () {
p = u_translate - 0.5 * u_size * (position * vec2(1, -1) + 1.0);
p = rotate2d(p, -u_angle * 0.017453292519943295) / u_scale * vec2(-1, 1);
gl_Position = vec4(position, 0, 1);
}`
applyRotation = () => `
// rotations, ported from d3-geo
void applyRotation(in vec3 rotate, inout float lambda, inout float phi) {
float x, y, rho, c, cosphi, z, deltaLambda, deltaPhi, deltaGamma, cosDeltaPhi,
sinDeltaPhi, cosDeltaGamma, sinDeltaGamma, k, circle, proj, a, b;
cosphi = cos(phi);
x = cos(lambda) * cosphi;
y = sin(lambda) * cosphi;
z = sin(phi);
deltaLambda = rotate.x * radians;
deltaPhi = rotate.y * radians;
deltaGamma = rotate.z * radians;
cosDeltaPhi = cos(deltaPhi);
sinDeltaPhi = sin(deltaPhi);
cosDeltaGamma = cos(deltaGamma);
sinDeltaGamma = sin(deltaGamma);
k = z * cosDeltaGamma - y * sinDeltaGamma;
lambda = atan(y * cosDeltaGamma + z * sinDeltaGamma,
x * cosDeltaPhi + k * sinDeltaPhi)
- deltaLambda;
k = k * cosDeltaPhi - x * sinDeltaPhi;
k = clamp(k, -1.0, 1.0); // avoid a hole at the poles
phi = asin(k);
}
`
height = {
// fullscreen?
if (width > 1000) return window.screen ? window.screen.height : width * .75;
const [[x0, y0], [x1, y1]] = d3
.geoPath(projection.fitWidth(width, { type: "Sphere" }))
.bounds({ type: "Sphere" });
const dy = Math.ceil(y1 - y0),
l = Math.min(Math.ceil(x1 - x0), dy);
projection.scale((projection.scale() * (l - 1)) / l).precision(0.2);
return dy;
}
projection.fitExtent([[10, 10], [width - 10, height - 10]], { type: "Sphere" })
d3 = require("d3@7", "d3-geo-projection@3")
import { checkbox, select } from "@jashkenas/inputs"
import {fullscreen} from "@fil/fullscreen"
fullscreen(map)
import { radians } from "@fil/math"
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