Hello, regl!regl-canvasObservable Plot + reglInstanced WebGL CirclesDrawing Instanced Lines with reglContour Plots with regl Observable PlotSelecting the Right Opacity for 2D Point CloudsSDF Points with reglAdaptive Contouring in Fragment ShadersStrange Attractors on the GPU, Part 1: ImplementationFake Transparency for 3D SurfacesBicubic Texture Interpolation using Linear Filtering
Regl Color Scale Selector
viewof colorscale = ColorScaleSelector(regl, {
label: "Color scale",
value: "Spectral",
invalidation
})
ColorScaleSelector(regl, {
value: "Spectral",
invalidation
})
colorscale
draw = {
regl.poll();
fillWithColorScale({ colorscale });
}
fillWithColorScale = regl({
vert: `
precision highp float;
attribute vec2 xy;
varying vec2 uv;
void main () {
uv = 0.5 + 0.5 * xy;
gl_Position = vec4(xy, 0, 1);
}`,
frag: `
precision highp float;
uniform sampler2D colorscale;
varying vec2 uv;
void main () {
gl_FragColor = texture2D(colorscale, uv);
}`,
attributes: { xy: [-4, -4, 4, -4, 0, 4] },
uniforms: { colorscale: regl.prop("colorscale.texture") },
depth: { enable: false },
count: 3
})
function lookupTable(interpolator, n = 256) {
return d3.quantize(interpolator, n).map((c) => {
return (c = d3.rgb(c)), [c.r, c.g, c.b, 255];
});
}
function ColorScaleSelector(regl, args = {}) {
const input = Inputs.select(COLOR_SCALE_NAMES, args);
const gradientOutput = html`<div></div>`;
const invert = html`<input type="checkbox" checked=${
args.invert ? '"checked"' : '""'
}>`;
const wrapper = html`<div>${input}<label>${invert} Invert</label>${gradientOutput}</div>`;
invert.parentElement.style.marginRight = "10px";
wrapper.style.display = "flex";
wrapper.style.flexDirection = "row";
wrapper.style.alignItems = "center";
gradientOutput.style.width = "150px";
gradientOutput.style.height = "17px";
gradientOutput.style.border = "1px solid #888";
gradientOutput.style.borderRadius = "2px";
input.style.marginRight = "10px";
input.style.maxWidth = args.label ? "275px" : "198px";
let texture = null;
function createTexture(name) {
const data = lookupTable(d3[`interpolate${name}`]);
if (invert.checked) {
data.reverse();
}
gradientOutput.style.backgroundImage = `linear-gradient(90deg, ${data
.map(
([r, g, b], i) =>
`rgb(${r},${g},${b}) ${(100 * i) / (data.length - 1)}%`
)
.join(",")})`;
texture = (texture || regl.texture)({
width: 256,
height: 1,
data: new Uint8ClampedArray(data.flat()),
min: "linear",
mag: "linear"
});
return { texture, data };
}
if (args.invalidation) {
invalidation.then(() => {
if (texture) texture.destroy();
});
}
function emitTexture() {
wrapper.value = {
...createTexture(input.value),
name: input.value
};
wrapper.dispatchEvent(new CustomEvent("input"));
}
invert.addEventListener("change", emitTexture);
input.addEventListener("change", emitTexture);
emitTexture({ target: { value: COLOR_SCALE_NAMES.indexOf(input.value) } });
return wrapper;
}
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