我一直在尝试使用Projector和Ray类来进行一些碰撞检测演示。起初，我只是尝试使用鼠标选择对象或拖动它们。我查看了使用这些对象的示例，但似乎没有一个解释Projector和Ray方法确切作用的注释。我有几个问题，希望有人能轻松回答。
Projector.projectVector()和Projector.unprojectVector()到底发生了什么以及它们之间的区别是什么？ 我注意到，在使用两个投影仪和射线对象的所有示例中，都会在创建射线之前调用unproject方法。 什么时候会使用projectVector？
我在此演示中使用以下代码来拖动鼠标时旋转立方体。能否用简单的语言解释当我使用mouse3D和camera进行unproject并创建射线时到底发生了什么？射线是否依赖于对unprojectVector（）的调用？
/** Event fired when the mouse button is pressed down */
function onDocumentMouseDown(event) {
event.preventDefault();
mouseDown = true;
mouse3D.x = mouse2D.x = mouseDown2D.x = (event.clientX / window.innerWidth) * 2 - 1;
mouse3D.y = mouse2D.y = mouseDown2D.y = -(event.clientY / window.innerHeight) * 2 + 1;
mouse3D.z = 0.5;
/** Project from camera through the mouse and create a ray */
projector.unprojectVector(mouse3D, camera);
var ray = new THREE.Ray(camera.position, mouse3D.subSelf(camera.position).normalize());
var intersects = ray.intersectObject(crateMesh); // store intersecting objects
if (intersects.length > 0) {
SELECTED = intersects[0].object;
var intersects = ray.intersectObject(plane);
}
}
/** This event handler is only fired after the mouse down event and
before the mouse up event and only when the mouse moves */
function onDocumentMouseMove(event) {
event.preventDefault();
mouse3D.x = mouse2D.x = (event.clientX / window.innerWidth) * 2 - 1;
mouse3D.y = mouse2D.y = -(event.clientY / window.innerHeight) * 2 + 1;
mouse3D.z = 0.5;
projector.unprojectVector(mouse3D, camera);
var ray = new THREE.Ray(camera.position, mouse3D.subSelf(camera.position).normalize());
if (SELECTED) {
var intersects = ray.intersectObject(plane);
dragVector.sub(mouse2D, mouseDown2D);
return;
}
var intersects = ray.intersectObject(crateMesh);
if (intersects.length > 0) {
if (INTERSECTED != intersects[0].object) {
INTERSECTED = intersects[0].object;
}
}
else {
INTERSECTED = null;
}
}
/** Removes event listeners when the mouse button is let go */
function onDocumentMouseUp(event) {
event.preventDefault();
/** Update mouse position */
mouse3D.x = mouse2D.x = (event.clientX / window.innerWidth) * 2 - 1;
mouse3D.y = mouse2D.y = -(event.clientY / window.innerHeight) * 2 + 1;
mouse3D.z = 0.5;
if (INTERSECTED) {
SELECTED = null;
}
mouseDown = false;
dragVector.set(0, 0);
}
/** Removes event listeners if the mouse runs off the renderer */
function onDocumentMouseOut(event) {
event.preventDefault();
if (INTERSECTED) {
plane.position.copy(INTERSECTED.position);
SELECTED = null;
}
mouseDown = false;
dragVector.set(0, 0);
}
Projector对象。请改用vector.unproject( camera );代替！ - circuitBurn