我试图解决的一般问题是找出立方体的哪个面向上。立方体可以一次向任何方向滚动90°。如果某个脸朝上，立方体就会消失。我正在使用补间来旋转立方体并改变它的位置。
我正在尝试通过创建一个新光线来解决这个问题，它的原点设置在立方体的正上方，并且它的方向向下延伸一小段距离，因此它只与立方体的上面相交。 violet thingy on top of die is ray cast downward into the cube
到现在为止还挺好。当我检查每个console.log()时，我将我的立方体作为交叉的对象，但是当我尝试通过faceIntersect.face访问交叉的面时，它似乎是未定义的。
有问题的功能：
function checkUpperFace(posX, posZ) {
// get position from passed x- and z-values (y is always above cube)
// and set direction and length of ray
var position = new THREE.Vector3( posX, 3, posZ );
var direction = new THREE.Vector3(0, -1, 0);
var far = 2;
// create ray, that goes downwards from above the cube
var cubeRaycaster = new THREE.Raycaster( position, direction, 0, far );
// get intersection with upper face of rolled cube
var faceIntersect = cubeRaycaster.intersectObject( currentCube );
// add a helper to see the ray
var arrowHelper = new THREE.ArrowHelper( direction, position, far, 0x770077 );
scene.add( arrowHelper );
console.log(faceIntersect); // object is shown with everything I want to know
console.log(faceIntersect.face); // is shown to be undefined
}
可能不是你的光线投射问题的解决方案，而是另一种方法：为什么不通过比较旋转欧拉角来简单地检测上面？例如。 （伪代码）：
if(cube.rotation.x % 360 == 0)
{
// upper face upwards
}
else if(cube.rotation.x % 360 == 90)
{
// left face upwards
}
你必须处理价值容差（85° - 95°）负旋转值和超出PI * 2范围的值，但除此之外，还不是那么容易吗？
最后我以@unx建议的方式做到了，但我真的想避免使用巨大的if-else语句，所以我使用了一个数组rotationLibrary，它具有与模具相应顶面的所有可能的旋转。但由于我用来旋转和移动骰子的补间，它的旋转值并不是真正的点，因此很难与固定的旋转值进行比较，因为我在数组中使用它们。
因此，我将模具的旋转值“标准化”为可用于将它们与rotationLibrary中的值进行比较的值。最后一步是将结果存储/更新到多维数据集对象本身顶部的哪个面上，这样我就可以随时获取它。
// spawn condition:
// 1 on top, 2 facing camera, 3 facing right (seen from camera),
// 4 facing left (see 3), 5 facing away from camera, 6 facing down
var rotationLibrary = [
{x: 0, y: 0, z: 0, face: 1},
{x: 0, y: 90, z: 0, face: 1},
{x: 180, y: 0, z: 180, face: 1},
{x: 0, y: -90, z: 0, face: 1},
{x: -90, y: 0, z: 0, face: 2},
{x: -90, y: 0, z: 90, face: 2},
{x: -90, y: 0, z: 180, face: 2},
{x: -90, y: 0, z: -90, face: 2},
{x: 0, y: 0, z: 90, face: 3},
{x: 90, y: 90, z: 0, face: 3},
{x: -90, y: -90, z: 0, face: 3},
{x: -90, y: 90, z: 180, face: 3},
{x: 180, y: 0, z: -90, face: 3},
{x: 0, y: 0, z: -90, face: 4},
{x: 90, y: -90, z: 0, face: 4},
{x: -90, y: 90, z: 0, face: 4},
{x: 180, y: 0, z: 90, face: 4},
{x: 90, y: 0, z: 0, face: 5},
{x: 90, y: 0, z: -90, face: 5},
{x: 90, y: 0, z: 180, face: 5},
{x: 90, y: 0, z: 90, face: 5},
{x: 90, y: 90, z: 90, face: 5},
{x: 0, y: 0, z: 180, face: 6},
{x: 180, y: -90, z: 0, face: 6},
{x: 180, y: 90, z: 0, face: 6},
{x: 180, y: 0, z: 0, face: 6}
];
function checkRotationsToGetUpperFace(cube) {
// create object with "normalized" (brought to quarter-circle-degree-values) degrees
var normalizedRotation = {
x: 0,
y: 0,
z: 0
};
normalizedRotation.x = getNormalizedDegree(cube.rotation._x);
normalizedRotation.y = getNormalizedDegree(cube.rotation._y);
normalizedRotation.z = getNormalizedDegree(cube.rotation._z);
// go through the library that has all the degrees with the corresponding upper face
for (var i = 0; i < rotationLibrary.length; i++) {
// check if the objects match, then get the face
if (rotationLibrary[i].x == normalizedRotation.x &&
rotationLibrary[i].y == normalizedRotation.y &&
rotationLibrary[i].z == normalizedRotation.z) {
cube.face = rotationLibrary[i].face;
}
}
// reattach cube for correct movement later
THREE.SceneUtils.attach(cube, scene, pivot);
}
function getNormalizedDegree(rotationValue) {
// transform rotation value into degree value
var rotValue = rotationValue / (Math.PI / 180);
// default value is 0, so only check if it should be 90°, 180° or -90°
var normalizedDegree = 0;
// x between 45° and 135° ( ~ 90)
if (rotValue > 45 && rotValue < 135) {
normalizedDegree = 90;
}
// x between -45° and -135° ( ~ -90)
else if (rotValue < -45 && rotValue > -135) {
normalizedDegree = -90;
}
// x between 135° and 215° or x between -135° and -215° ( ~ 180)
else if ((rotValue > 135 && rotValue < 215) || (rotValue < -135 && rotValue > -215)) {
normalizedDegree = 180;
}
return normalizedDegree;
}
（Qazxswpoi）