3.1 basic geometry
Circular (CircleGeometry)
Description:
Circular or sector can be created
Constructor:
THREE.CircleGeometry(radius, segments, thetaStart, thetaLength)
radius: radius;
segments: the number of slices to a point as the center (cut the cake?);
thetaStart: starting position;
thetaLength: fan span;
A complete code example and demo effects:
1 <!DOCTYPE html> 2 <html lang="en"> 3 4 <head> 5 <meta charset="UTF-8"> 6 <meta name="viewport" content="width=device-width, initial-scale=1.0"> 7 <meta http-equiv="X-UA-Compatible" content="ie=edge"> 8 <script type="text/javascript" src="./three.js"></script> 9 <title>Document</title> 10 </head> 11 12 <body onload="init()"> 13 <script> 14 function init() { 15 var renderer = new THREE.WebGLRenderer(); 16 renderer.setSize(800, 600); 17 document.getElementsByTagName('body')[0].appendChild(renderer.domElement); 18 19 renderer.setClearColor(0x00000); 20 var scene = new THREE.Scene(); 21 var aspect = window.innerWidth / window.innerHeight; 22 var camera = new THREE.OrthographicCamera(-4 * aspect, 4 * aspect, -3 * aspect, 3 * aspect, 1, 500); 23 camera.position.set ( 0 , 0 , 200 is ); 24 camera.lookAt ( new new THREE.Vector3 ( 0 , 0 , 0 )); 25 scene.add (Camera); 26 is 27 var Circle = new new THREE.Mesh ( new new THREE.CircleGeometry ( 3 , 50 , Math.PI, Math.PI / 3 * 4 ), 28 // Math.PI / 3 * 4) how come? : Math.PI * 2 is a full circle (360 degrees projection plane), then Math.PI * 2 * 2/3 to 2/3 can draw a circle (a sector region) 29 new THREE.MeshBasicMaterial({ 30 color: 0xff0000, 31 wireframe: true 32 }) 33 ) 34 scene.add(circle) 35 36 37 renderer.render(scene, camera); 38 } 39 </script> 40 </body> 41 42 </html>
