使用colladaloader时，three.js png纹理不透明

Question

我从第二次生命中保存了一个collada文件，并使用3js和colladaloader2渲染它。除了使用透明纹理文件的部分外，图像看起来很好。该文件是一个透明的png。透明部分呈现为白色。

我正在使用REVISION：＆＃34; 78＆＃34; of three.js

这是代码段

    <script src="js/three.min.js"></script>
    <script src="js/ColladaLoader2.js"></script>
    <script src="js/Detector.js"></script>

    <script>

        var container;
        var camera, scene, renderer;
        var group;

        var targetRotation = 0;
        var targetRotationOnMouseDown = 0;

        var mouseX = 0;
        var mouseXOnMouseDown = 0;

        var windowHalfX = window.innerWidth / 2;
        var windowHalfY = window.innerHeight / 2;

        var loader = new THREE.ColladaLoader();
        loader.options.convertUpAxis = true;
        loader.load('models/collada/ASB1/American_Saddlebred.dae', function(collada) {
            dae = collada.scene;
            dae.scale.x = dae.scale.y = dae.scale.z = 100.0;
            dae.updateMatrix();

            init();
            animate();

            function init() {
                container = document.createElement('div');
                document.body.appendChild(container);

                var info = document.createElement('div');
                info.style.position = 'absolute';
                info.style.top = '10px';
                info.style.width = '100%';
                info.style.textAlign = 'center';
                info.innerHTML = 'Drag to spin';
                container.appendChild(info);

                scene = new THREE.Scene();

                camera = new THREE.PerspectiveCamera(50, window.innerWidth / window.innerHeight, 1, 1000);
                camera.position.set(0, 50, 800);
                scene.add(camera);

                var light = new THREE.AmbientLight( 0xFFFFFF ); // soft white light
                camera.add(light);

                renderer = new THREE.WebGLRenderer( { antialias: true, alpha: true} );
                renderer.setClearColor( 0x333333, 1);
                renderer.setClearAlpha = 0.003;
                renderer.setPixelRatio(window.devicePixelRatio);
                renderer.setSize(window.innerWidth, window.innerHeight);
                container.appendChild( renderer.domElement );