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《Three.js 入门指南》3.1.1 - 基本几何形状 -圆形(CircleGeometry)

3.1 基本几何形状

圆形(CircleGeometry)

说明:

可以创建圆形或者扇形

构造函数:

 THREE.CircleGeometry(radius, segments, thetaStart, thetaLength) 

radius:半径;

segments:以一个点为中心的切片数(切蛋糕?);

thetaStart:开始位置;

thetaLength:扇面跨度;

一个完整的代码示例demo和效果:

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <script type="text/javascript" src="./three.js"></script>
    <title>Document</title>
</head>

<body onload="init()">
    <script>
        function init() {
            var renderer = new THREE.WebGLRenderer();
            renderer.setSize(800, 600);
            document.getElementsByTagName('body')[0].appendChild(renderer.domElement);

            renderer.setClearColor(0x00000);
            var scene = new THREE.Scene();
            var aspect = window.innerWidth / window.innerHeight;
            var camera = new THREE.OrthographicCamera(-4 * aspect, 4 * aspect, -3 * aspect, 3 * aspect, 1, 500);
            camera.position.set(0, 0, 200);
            camera.lookAt(new THREE.Vector3(0, 0, 0));
            scene.add(camera);

            var circle = new THREE.Mesh(new THREE.CircleGeometry(3, 50, Math.PI, Math.PI / 3 * 4),
                // Math.PI / 3 * 4)怎么来的? : Math.PI * 2 是一整个圆(平面投影360度),那么Math.PI*2 * 2/3 就可以画出一个2/3的圆(扇形区域)
                new THREE.MeshBasicMaterial({
                    color: 0xff0000,
                    wireframe: true
                })
            )
            scene.add(circle)


            renderer.render(scene, camera);
        }
    </script>
</body>

</html>

  

 

posted @ 2019-12-13 08:25  暮冬有八  阅读(1720)  评论(0编辑  收藏  举报
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