版本：9.3.0
模型首次渲染事件监听

监听已加载三维模型的首次渲染完成事件。
<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8"/>
    <title>模型首次渲染事件监听</title>
    <meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no"/>
    <style>
        body {
            margin: 0;
            padding: 0;
        }

        #map {
            position: absolute;
            top: 0;
            bottom: 0;
            width: 100%;
        }

        #btn {
            position: absolute;
            top: 20px;
            left: 20px;
        }

        #show {
            position: absolute;
            top: 20px;
            right: 20px;
            color: #000000;
            font-size: 25px;
            font-weight:bold;
        }

    </style>
    <script src="https://delivery.mapmost.com/cdn/sdk/webgl/v9.3.0/mapmost-webgl-min.js"></script>
</head>

<body>
<div id="map"></div>
<button id="btn" onclick="loadModel()">加载模型</button>
<div id="show"></div>
<script>
    let map = new mapmost.Map({
        container: 'map',  
        style: "<your style url>", 
        center: [120.745071002000068, 31.306268408000039], 
        zoom: 17, 
        pitch: 60, 
        bearing: 0,
        userId: '***', // 授权码 
        env3D:{
            exposure: 0.72,
        }
    });

    function loadModel() {

        document.getElementById("show").innerText = "模型加载中······";

        let models_obj = ["CX.glb", "F1.glb", "F2.glb", "F3.glb"].map(item => ({
            type: 'glb',
            url: "../example_data/aoti_new/" + item
        }));

        let options = {
            id: 'model_id',
            type: 'model',
            models: models_obj,
            project: "3857",
            center: [120.744471002000068, 31.306768408000039, 3.617],
            callback: function (group, layer) {
                layer.onAfterRender(group).then(function () {
                    document.getElementById("show").innerText = "首次渲染完成!";
                })
            }
        };
        map.addLayer(options);
    }
</script>
</body>

</html>