files/en-us/web/api/xrlightestimate/primarylightintensity/index.md
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The read-only primaryLightIntensity property of the {{DOMxRef("XRLightEstimate")}} interface returns a {{domxref("DOMPointReadOnly")}} representing the intensity of the primary light source from the probeSpace of an {{domxref("XRLightProbe")}}.
A {{domxref("DOMPointReadOnly")}} object where an RGB value is mapped to the x, y, and z values. The w value is always 1.0. If no estimated values from the user's environment are available, the point will be {x: 0.0, y: 0.0, z: 0.0, w: 1.0}, representing no illumination.
Within an {{domxref("XRFrame")}} loop, you can use the primaryLightDirection and primaryLightIntensity properties
to render shadows based on the most prominent light source, for example.
const lightProbe = await xrSession.requestLightProbe();
// frame loop
function onXRFrame(time, xrFrame) {
let lightEstimate = xrFrame.getLightEstimate(lightProbe);
// Render lights
// Available properties
lightEstimate.primaryLightDirection;
lightEstimate.primaryLightIntensity;
}
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