[英]How can I rotate a sphere around a cube in Three.js
我ve seen different options to rotate objects but I don
知道如何應用它們。 我對javascript很陌生。 我創建了立方體和球體,並設法使球體繞其自身的軸旋轉,但是我需要它繞立方體旋轉。歡迎任何幫助。 這是我的代碼:
<html>
<head>
<title>My first Three.js app</title>
<style>
body { margin: 0; }
canvas { width: 100%; height: 100% }
</style>
</head>
<body>
<script src="js/three.js"></script>
<script>
var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera( 100, window.innerWidth/window.innerHeight, 0.1, 1000 );
var renderer = new THREE.WebGLRenderer();
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );
camera.position.z = 25;
var loader = new THREE.TextureLoader();
var texture = loader.load('crate.jpg');
var geometry = new THREE.BoxGeometry( 7, 7, 7 );
var material = new THREE.MeshBasicMaterial({map: texture});
var cube = new THREE.Mesh(geometry, material);
cube.rotation.x += 0.6;
cube.rotation.y += 0.6;
scene.add( cube );
var loader = new THREE.TextureLoader();
var texture = loader.load('earth.jpg');
var geometry = new THREE.SphereGeometry( 1, 50, 50 );
var material = new THREE.MeshBasicMaterial( {map: texture} );
var sphere = new THREE.Mesh( geometry, material );
scene.add( sphere );
var render = function () {
requestAnimationFrame( render );
sphere.position.set(6, 0, 15);
sphere.rotation.y += 0.01;
renderer.render(scene, camera);
};
render();
</script>
</body>
</html>
在這種情況下,我建議使用Object3D
作為球體的容器。 然后將此容器放置在立方體的位置/中央並旋轉它。
...
var cube = new THREE.Mesh(geometry, material);
cube.rotation.x += 0.6;
cube.rotation.y += 0.6;
scene.add( cube );
...
var sphere = new THREE.Mesh( geometry, material );
sphere.position.set(0,0,15); // offset from center
var sphereContainer = new THREE.Object3D();
sphereContainer.add( sphere );
sphereContainer.position.copy( cube.position ); // optional, in case you've set the position of the cube
scene.add( sphereContainer );
var render = function () {
requestAnimationFrame( render );
sphere.rotation.y += 0.01; // rotate around its own axis
sphereContainer.rotation.y += 0.01; // rotate around cube
renderer.render(scene, camera);
};
我找到了使之工作的方法。 我使用了rotateAboutWorldAxis函數,它看起來像這樣:
...
sphere.position.set(0,0,15); // offset from center
function rotateAboutWorldAxis(object, axis, angle) {
var rotationMatrix = new THREE.Matrix4();
rotationMatrix.makeRotationAxis( axis.normalize(), angle );
var currentPos = new THREE.Vector4(object.position.x, object.position.y, object.position.z, 1.5);
var newPos = currentPos.applyMatrix4(rotationMatrix);
object.position.x = newPos.x;
object.position.y = newPos.y;
object.position.z = newPos.z;
}
並在render函數中輸入:
var yAxis = new THREE.Vector3(0,50,0);
rotateAboutWorldAxis(sphere,yAxis,Math.PI / 180);
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