问题
I want to make it such that I can move around in the following manner in three.js by moving the perspectivecamera:
- "hit a key or button to move the camera forward into the direction im looking at"
- "hit a key or button to move the camera downward below the direction im looking at"
- "hit a key or button to pitch the camera such that the "fov" is of a different value
- "hit keys or buttons to pitch the camera such that i am rotating as if pivoted at the place the camera is to be able to see whats left and right of me
The following is my current code. Based on what I am seeing, it appears that PerspectiveCamera from the docs does not appear to have any methods like "setFov" or anything like that, simply "camera.fov = " does not appear to have any effect like the meshes after the camera has been initialized. So how would I properly be able to do the above?:
<!DOCTYPE html>
<html>
<head>
<title>Example 01.03 - Materials and light</title>
<script type="text/javascript" src="../libs/three.js"></script>
<script type="text/javascript" src="../libs/jquery-1.9.0.js"></script>
<script type="text/javascript" src="../libs/stats.js"></script>
<style>
body{
/* set margin to 0 and overflow to hidden, to go fullscreen */
margin: 0;
overflow: hidden;
}
</style>
</head>
<body>
<div id="Stats-output">
</div>
<!-- Div which will hold the Output -->
<div id="WebGL-output">
</div>
<!-- Javascript code that runs our Three.js examples -->
<script type="text/javascript">
// once everything is loaded, we run our Three.js stuff.
$(function () {
var stats = initStats();
// create a scene, that will hold all our elements such as objects, cameras and lights.
var scene = new THREE.Scene();
// create a camera, which defines where we're looking at.
var camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
// create a render and set the size
var renderer = new THREE.WebGLRenderer();
renderer.setClearColorHex(0xEEEEEE, 1.0);
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.shadowMapEnabled = true;
// create the ground plane
var planeGeometry = new THREE.PlaneGeometry(60,20,1,1);
var planeMaterial = new THREE.MeshLambertMaterial({color: 0xffffff});
var plane = new THREE.Mesh(planeGeometry,planeMaterial);
plane.receiveShadow = true;
// rotate and position the plane
plane.rotation.x=-0.5*Math.PI;
plane.position.x=15
plane.position.y=0
plane.position.z=0
// add the plane to the scene
scene.add(plane);
// create a cube
var cubeGeometry = new THREE.CubeGeometry(4,4,4);
var cubeMaterial = new THREE.MeshLambertMaterial({color: 0xff0000});
var cube = new THREE.Mesh(cubeGeometry, cubeMaterial);
cube.castShadow = true;
// position the cube
cube.position.x=-4;
cube.position.y=3;
cube.position.z=0;
// add the cube to the scene
scene.add(cube);
var sphereGeometry = new THREE.SphereGeometry(4,20,20);
var sphereMaterial = new THREE.MeshLambertMaterial({color: 0x7777ff});
var sphere = new THREE.Mesh(sphereGeometry,sphereMaterial);
// position the sphere
sphere.position.x=20;
sphere.position.y=0;
sphere.position.z=2;
sphere.castShadow=true;
// add the sphere to the scene
scene.add(sphere);
// position and point the camera to the center of the scene
camera.position.x = -30;
camera.position.y = 40;
camera.position.z = 30;
camera.lookAt(scene.position);
// add subtle ambient lighting
var ambientLight = new THREE.AmbientLight(0x0c0c0c);
scene.add(ambientLight);
// add spotlight for the shadows
var spotLight = new THREE.SpotLight( 0xffffff );
spotLight.position.set( -40, 60, -10 );
spotLight.castShadow = true;
scene.add( spotLight );
// add the output of the renderer to the html element
$("#WebGL-output").append(renderer.domElement);
// call the render function
var step=0;
render();
function render() {
stats.update();
// rotate the cube around its axes
cube.rotation.x += 0.02;
cube.rotation.y += 0.02;
cube.rotation.z += 0.02;
// bounce the sphere up and down
step+=0.04;
sphere.position.x = 20+( 10*(Math.cos(step)));
sphere.position.y = 2 +( 10*Math.abs(Math.sin(step)));
// render using requestAnimationFrame
requestAnimationFrame(render);
renderer.render(scene, camera);
}
function initStats() {
var stats = new Stats();
stats.setMode(0); // 0: fps, 1: ms
// Align top-left
stats.domElement.style.position = 'absolute';
stats.domElement.style.left = '0px';
stats.domElement.style.top = '0px';
$("#Stats-output").append( stats.domElement );
return stats;
}
});
</script>
</body>
</html>
回答1:
I believe you simply need to understand the components of the camera's matrix to realize what you want. The three.js "camera" is a 4x4 matrix of the classic linear algebra type.
4x4 matrix = [a b c d
e f g h
i j k l
n m o p]
The 3x3 inner matrix is literally the orientation of your camera:
camera orientation = [a b c
e f g
i j k]
Meaning the vector { a, b, c } is the direction vector pointing to the camera's right, from the camera's pov. The vector { e, f, g } is the direction vector pointing up, from the camera's point of view. And the vector { i, j, k } is the director vector pointing in the direction the camera is facing.
Together these 3 vectors compose the orientation of the camera.
They can be further envisioned by holding your left hand in front of you like this:
Each finger is pointing in the positive direction of the camera's pov, and they likewise equal the rotation factors necessary to orient the camera.
And the other, non-rotation components { n, m, o } is the x, y, z position of the camera.
To move in the direction of the camera, add the vector { i, j, k } to { n, m, o }.
To move to the right, from the camera's pov, add the vector { a, b, c } to { n, m, o }.
To move up, from the camera's pov, add the vector { e, f, g } to { n, m, o }.
And, of course, to move in the opposite directions add the negatives of those orientation vectors.
来源：https://stackoverflow.com/questions/17661571/how-to-properly-change-the-camera-view-to-move-forward-and-backward-into-a-scene