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[WIP] 1404 Get Raster Pixel Color At Location #12116

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[WIP] 1404 Get Raster Pixel Color At Location #12116

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f348763
debug demo page
jbeuckm Apr 8, 2022
a80a3a7
version of render to get pixel color
jbeuckm Apr 8, 2022
ee09de4
simplify render function
jbeuckm Apr 10, 2022
c71b104
pixel ratio
Jul 26, 2022
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61 changes: 61 additions & 0 deletions debug/query-raster.html
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Original file line number Diff line number Diff line change
@@ -0,0 +1,61 @@
<!DOCTYPE html>
<html>
<head>
<title>Mapbox GL JS debug page</title>
<meta charset="utf-8" />
<meta
name="viewport"
content="width=device-width, initial-scale=1.0, user-scalable=no"
/>
<link rel="stylesheet" href="../dist/mapbox-gl.css" />
<style>
body {
margin: 0;
padding: 0;
}
html,
body,
#map {
height: 100%;
}
#swatch {
position: absolute;
top: 0;
left: 0;
width: 100px;
height: 100px;
}
</style>
</head>

<body>
<div id="map"></div>
<div id="swatch"></div>

<script src="../dist/mapbox-gl-dev.js"></script>
<script src="../debug/access_token_generated.js"></script>
<script>
var map = (window.map = new mapboxgl.Map({
container: "map",
zoom: 12.5,
center: [-77.01866, 38.888],
style: "mapbox://styles/mapbox/satellite-v9",
hash: true,
}));

map.on("load", function () {

map.on("mousemove", (event) => {
const pixel = map.colorForLayerPoint(
"satellite",
event.point
);

document.getElementById(
"swatch"
).style.backgroundColor = `rgba(${pixel[0]},${pixel[1]},${pixel[2]},${pixel[3]})`;
});
});
</script>
</body>
</html>
55 changes: 55 additions & 0 deletions src/render/painter.js
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Original file line number Diff line number Diff line change
Expand Up @@ -718,6 +718,61 @@ class Painter {
}
}

colorForLayerPoint(layerId: string, point: PointLike) {

const layer = this.style._layers[layerId];
if (layer.type !== 'raster') { return }

const sourceCache = this.style._getLayerSourceCache(layer);

sourceCache.prepare(this.context);

const coordsAscending: Array<OverscaledTileID> = sourceCache.getVisibleCoordinates();
const coordsDescending: Array<OverscaledTileID> = coordsAscending.slice().reverse();

// Rebind the main framebuffer now that all offscreen layers have been rendered:
// this.context.bindFramebuffer.set(null);
this.context.viewport.set([0, 0, this.width, this.height]);

this.context.clear({
color: 'rgba(0,0,0,0)', //options.showOverdrawInspector ? Color.black : clearColor,
depth: 1,
});
this.clearStencil();

this._showOverdrawInspector = false; //options.showOverdrawInspector;

this.renderPass = "translucent";

// For symbol layers in the translucent pass, we add extra tiles to the renderable set
// for cross-tile symbol fading. Symbol layers don't use tile clipping, so no need to render
// separate clipping masks
const coords = sourceCache
? coordsDescending
: undefined;

this._renderTileClippingMasks(
layer,
sourceCache,
sourceCache ? coordsAscending : undefined
);
this.renderLayer(this, sourceCache, layer, coords);

const gl = this.context.gl;
var pixel = new Uint8Array(4);
gl.readPixels(
point.x * window.devicePixelRatio,
this.height - point.y * window.devicePixelRatio,
1,
1,
gl.RGBA,
gl.UNSIGNED_BYTE,
pixel
);

return pixel;
}

renderLayer(painter: Painter, sourceCache?: SourceCache, layer: StyleLayer, coords?: Array<OverscaledTileID>) {
if (layer.isHidden(this.transform.zoom)) return;
if (layer.type !== 'background' && layer.type !== 'sky' && layer.type !== 'custom' && !(coords && coords.length)) return;
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4 changes: 4 additions & 0 deletions src/ui/map.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1504,6 +1504,10 @@ class Map extends Camera {

/** @section {Querying features} */

colorForLayerPoint(layerId: string, point: PointLike) {
return this.painter.colorForLayerPoint(layerId, point)
}

/**
* Returns an array of [GeoJSON](http://geojson.org/)
* [Feature objects](https://tools.ietf.org/html/rfc7946#section-3.2)
Expand Down