Pie*_*mps 5 javascript three.js
我加载图像以显示精灵。
但似乎代码在图像完全加载之前继续执行：
但是我不知道如何使用 Threejs 等待图像完全加载。我可以帮忙吗？
代码可以在这里测试：http : //www.planetarium2016.com/sprite.html
这是我的代码：
<html>
<head>
<title>My first three.js app</title>
<style>
body { margin: 0; }
canvas { width: 100%; height: 100% }
</style>
</head>
<body>
<script src="https://rawgithub.com/mrdoob/three.js/master/build/three.js"></script>
<script>
var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 1, 500);
camera.position.set(0, 10, 100);
camera.lookAt(new THREE.Vector3(0, 0, 0));
var renderer = new THREE.WebGLRenderer();
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );
var material = new THREE.LineBasicMaterial({ color: 0x0000ff });
var geometry = new THREE.Geometry();
geometry.vertices.push(new THREE.Vector3(-10, 0, 0));
geometry.vertices.push(new THREE.Vector3(0, 10, 0));
geometry.vertices.push(new THREE.Vector3(10, 0, 0));
geometry.vertices.push(new THREE.Vector3(0, 0, -10));
var line = new THREE.Line(geometry, material);
scene.add(line);
var loader = new THREE.TextureLoader();
var spriteMap = loader.load("https://codefisher.org/static/images/pastel-svg/256/bullet-star.png");
//+-----------------------------------------------------------+
//| I need here to wait for the image to be fully loaded |
//| This cheat is fool: while (spriteMap.image.width == 0); |
//+-----------------------------------------------------------+
var spriteMaterial = new THREE.SpriteMaterial( { map: spriteMap, color: 0xffffff } );
var sprite = new THREE.Sprite( spriteMaterial );
sprite.scale.set(256, 256, 1);
sprite.position.set( 0, 0, 10 );
scene.add( sprite );
//camera.position.z = 2;
var render = function () {
requestAnimationFrame( render );
renderer.render(scene, camera);
};
render();
</script>
</body>
</html>
三 JS TextureLoader有点老了...
我会通过使用 JavaScript 承诺来解决这个问题。我将您的three.js 代码分为两个主要功能，一个用于初始化，另一个用于带有requestAnimationFrame 的动画。这种方式更具可读性，特别是如果您打算执行异步任务：
var scene;
var camera;
var renderer;
var spriteMap;
var loaderPromise = new Promise(function(resolve, reject) {
function loadDone(x) {
console.log("loader successfully completed loading task");
resolve(x); // it went ok!
}
var loader = new THREE.TextureLoader();
loader.load("https://codefisher.org/static/images/pastel-svg/256/bullet-star.png", loadDone);
});
loaderPromise.
then(function(response) {
spriteMap = response; //assign loaded image data to a variable
init(); //initialize the render
requestAnimationFrame( render );
}, function(err) {
console.log(err);
});
function init() {
scene = new THREE.Scene();
camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 1, 500);
camera.position.set(0, 10, 100);
camera.lookAt(new THREE.Vector3(0, 0, 0));
renderer = new THREE.WebGLRenderer();
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );
var material = new THREE.LineBasicMaterial({ color: 0x0000ff });
var geometry = new THREE.Geometry();
geometry.vertices.push(new THREE.Vector3(-10, 0, 0));
geometry.vertices.push(new THREE.Vector3(0, 10, 0));
geometry.vertices.push(new THREE.Vector3(10, 0, 0));
geometry.vertices.push(new THREE.Vector3(0, 0, -10));
var line = new THREE.Line(geometry, material);
scene.add(line);
var spriteMaterial = new THREE.SpriteMaterial( { map: spriteMap, color: 0xffffff } );
var sprite = new THREE.Sprite( spriteMaterial );
sprite.scale.set(256, 256, 1);
sprite.position.set( 0, 0, 10 );
scene.add( sprite );
}
function render() {
renderer.render(scene, camera);
requestAnimationFrame( render );
}
解决方案在这里：https ://thirdjs.org/docs/#api/loaders/TextureLoader
这是解决我的问题的代码：
var url = "https://codefisher.org/static/images/pastel-svg/256/bullet-star.png";
var loader = new THREE.TextureLoader();
var spriteMaterial;
loader.load(url,
function(texture)
{
spriteMaterial = new THREE.SpriteMaterial( { map: texture, color: 0x0000ff } );
}
);
var sprite = new THREE.Sprite( spriteMaterial );