babylonjs 雷达效果

要实现Babylonjs中的雷达效果，可以使用以下步骤：

1. 创建一个圆形平面，作为雷达的底座。

var radarBase = BABYLON.MeshBuilder.CreateDisc("radarBase", { radius: 5, tessellation: 64 }, scene);
radarBase.material = new BABYLON.StandardMaterial("radarBaseMaterial", scene);
radarBase.material.diffuseColor = new BABYLON.Color3(0.3, 0.3, 0.3);
radarBase.material.specularColor = BABYLON.Color3.Black();

2. 创建多个圆柱体，作为雷达扫描的线。

var radarLines = [];
for (var i = 0; i < 8; i++) {
    var radarLine = BABYLON.MeshBuilder.CreateCylinder("radarLine" + i, { height: 10, diameterTop: 0.1, diameterBottom: 0.5 }, scene);
    radarLine.position.y = 5;
    radarLine.rotation.x = Math.PI / 2;
    radarLine.rotation.z = Math.PI / 4 * i;
    radarLine.material = new BABYLON.StandardMaterial("radarLineMaterial" + i, scene);
    radarLine.material.diffuseColor = new BABYLON.Color3(0.8, 0.8, 0.8);
    radarLine.material.specularColor = BABYLON.Color3.Black();
    radarLines.push(radarLine);
}

3. 创建一个扫描动画，将每个圆柱体逐渐旋转到下一个位置。

var radarScanAnimation = new BABYLON.Animation("radarScanAnimation", "rotation.z", 30, BABYLON.Animation.ANIMATIONTYPE_FLOAT, BABYLON.Animation.ANIMATIONLOOPMODE_CYCLE);
var radarScanKeys = [];
for (var i = 0; i <= 8; i++) {
    radarScanKeys.push({
        frame: i * 30,
        value: Math.PI / 4 * i
    });
}
radarScanAnimation.setKeys(radarScanKeys);
for (var i = 0; i < 8; i++) {
    radarLines[i].animations.push(radarScanAnimation);
}
scene.beginAnimation(radarLines, 0, 240, true);

4. 创建一个跟随鼠标移动的标记，表示雷达的目标位置。

var radarTarget = BABYLON.MeshBuilder.CreateSphere("radarTarget", { diameter: 0.5 }, scene);
radarTarget.material = new BABYLON.StandardMaterial("radarTargetMaterial", scene);
radarTarget.material.diffuseColor = new BABYLON.Color3(1, 0, 0);
radarTarget.material.specularColor = BABYLON.Color3.Black();
scene.onPointerMove = function(evt) {
    var pickResult = scene.pick(evt.clientX, evt.clientY);
    if (pickResult.hit) {
        radarTarget.position = pickResult.pickedPoint;
    }
};

这样就可以实现一个简单的雷达效果，其中雷达扫描的线和雷达目标位置可以根据实际需求进行调整和优化。