[BUG]: scatterpolargl drops points between 10000 and 100000 points #8148

Description

scatterpolargl does not set opts.marker.snap as scattergl does. This limits how many markers are displayed at certain zoom levels due to how regl-scatter2d handles rendering with its default snap value (10000). See #4323.

Screenshots

scatterpolargl vs. scattergl with the same data:

Steps to reproduce

• Open Plotly devtools and paste the following into the browser devtools console:

const n = 90000;
const gauss = () => (Math.random() + Math.random() + Math.random() + Math.random() - 2) / 2;

const x = [];
const y = [];
const r = [];
const theta = [];
for (let i = 0; i < n; i++) {
    const px = 0.05 * gauss();
    const py = 0.05 * gauss();
    x.push(px);
    y.push(py);
    r.push(Math.hypot(px, py));
    theta.push(Math.atan2(py, px) * 180 / Math.PI);
}

const marker = {color: 'rgba(0,0,255,0.01)', size: 3};

Plotly.newPlot(gd, [
    {type: 'scatterpolargl', mode: 'markers', r, theta, marker, subplot: 'polar'},
    {type: 'scattergl', mode: 'markers', x, y, marker, xaxis: 'x', yaxis: 'y'}
], {
    width: 760,
    height: 420,
    showlegend: false,
    polar: {domain: {x: [0, 0.45]}},
    xaxis: {domain: [0.58, 1], anchor: 'y'},
    yaxis: {domain: [0.1, 0.9], anchor: 'x', scaleanchor: 'x'}
});

• Note that the scatterpolargl plot is pale compared to scattergl

Notes

• For a scatterpolargl trace with more than 10000 points, regl-scatter2d builds its own cluster tree. It then draws only the level-of-detail subset of points. The same data on scattergl draws every point.
• scattergl had this bug but it got fixed in Fix scattergl mising points plot and react #4323
• The same fix can be applied to this trace: set opts.marker.snap = len after convert.style in src/traces/scatterpolargl/calc.js