Shape

HTML

<script src="//cdn.rawgit.com/mrdoob/three.js/master/build/three.js"></script>

JavaScript

var camera, scene, renderer, controls;

init();
animate()

function init() {

    scene = new THREE.Scene();
    
    camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 0.1, 10000 );
    camera.position.set( 0, 1, 5 );
    scene.add( camera );
    
    var shape = new THREE.Shape();
    shape.curves.push( new THREE.LineCurve( new THREE.Vector2( 0, 0 ), new THREE.Vector2( 2, 0 ) ) );
    shape.curves.push( new THREE.LineCurve( new THREE.Vector2( 1, 2 ), new THREE.Vector2( 0, 2.849493 ) ) );
    shape.curves.push( new THREE.LineCurve( new THREE.Vector2( - 1, 2 ), new THREE.Vector2( - 0.5, 0 ) ) );
   
    var geometry = new THREE.ShapeBufferGeometry( shape );
    var mesh = new THREE.Mesh( geometry,  new THREE.MeshBasicMaterial( { color: 0xff0000 } ) );

    scene.add( mesh );
    
    scene.add( new THREE.AxesHelper( 10 ) );
    
     // renderer
    renderer = new THREE.WebGLRenderer();
    renderer.setSize( window.innerWidth, window.innerHeight );
    document.body.appendChild( renderer.domElement );
    
}

function animate() {

    requestAnimationFrame( animate );
    renderer.render( scene, camera );
    
}