Question

我正在尝试使用Frustum来检测对象是否在屏幕的正方形区域内（请参见下图）。这是一个UI图像，它是作为目标盒而不是3D对象的。

原始帖子在这里：Detect if an object in 3D space is within/touches a UI image's bounds

现在，我可以得到“视锥”并绘制框以起作用，但只能朝一个方向看。

我需要能够在摄像机转动时计算出新点，但我不知道怎么做。

下面的代码有点用，但是我需要偏移位置，以便它们在相机移动时与视图对齐。

编辑：现在，除了绘制方框并使之正常工作之外，什么也不会发生。碰撞检测随之而来。

// Draw aimbox
Vector3 camPosOffset = camPos + cam.transform.forward * maxDistance;

float frustumHeight = (2.0f * maxDistance * Mathf.Tan(cam.fieldOfView * 0.5f * Mathf.Deg2Rad));

cubeVerts[0] = new Vector3(camPos.x, camPos.y, camPos.z);
cubeVerts[1] = new Vector3(camPos.x, camPos.y, camPos.z);
cubeVerts[2] = new Vector3(camPos.x, camPos.y, camPos.z);
cubeVerts[3] = new Vector3(camPos.x, camPos.y, camPos.z);
cubeVerts[4] = new Vector3(camPosOffset.x - frustumHeight, camPosOffset.y + frustumHeight, camPosOffset.z);
cubeVerts[5] = new Vector3(camPosOffset.x + frustumHeight, camPosOffset.y + frustumHeight, camPosOffset.z);
cubeVerts[6] = new Vector3(camPosOffset.x - frustumHeight, camPosOffset.y - frustumHeight, camPosOffset.z);
cubeVerts[7] = new Vector3(camPosOffset.x + frustumHeight, camPosOffset.y - frustumHeight, camPosOffset.z);

for (int i = 0; i < edges.Length; i += 2)
{
    Debug.DrawLine(cubeVerts[edges[i]], cubeVerts[edges[i + 1]], Color.red);
}

https://imgur.com/iXQlE04

Answer 1

最简单的版本：将瞄准器作为相机的子代。

替代解决方案，对于前4个版本，也请使用camPosOffset，如下所示：

cubeVerts[0] = new Vector3(camPosOffset.x - frustumHeight, camPosOffset.y + frustumHeight, camPosOffset.z);
cubeVerts[1] = new Vector3(camPosOffset.x + frustumHeight, camPosOffset.y + frustumHeight, camPosOffset.z);
cubeVerts[2] = new Vector3(camPosOffset.x - frustumHeight, camPosOffset.y - frustumHeight, camPosOffset.z);
cubeVerts[3] = new Vector3(camPosOffset.x + frustumHeight, camPosOffset.y - frustumHeight, camPosOffset.z);
cubeVerts[4] = new Vector3(camPosOffset.x - frustumHeight, camPosOffset.y + frustumHeight, camPosOffset.z) + cam.forward * 3;
cubeVerts[5] = new Vector3(camPosOffset.x + frustumHeight, camPosOffset.y + frustumHeight, camPosOffset.z) + cam.forward * 3;
cubeVerts[6] = new Vector3(camPosOffset.x - frustumHeight, camPosOffset.y - frustumHeight, camPosOffset.z) + cam.forward * 3;
cubeVerts[7] = new Vector3(camPosOffset.x + frustumHeight, camPosOffset.y - frustumHeight, camPosOffset.z) + cam.forward * 3;

Answer 2

摆弄了将近两天后，我完全得到了想要的东西。

        //Draw aimbox

    float frustumHeight = ((2.0f * maxDistance * Mathf.Tan(cam.fieldOfView/20 * 0.5f * Mathf.Deg2Rad))); //cam.fieldOfView/20, I divide by 20 because I only need a small square of the view

    cubeVerts[0] = cam.transform.position + cam.transform.forward * 25; //25 is the distance from the camera to the object it follows
    cubeVerts[1] = cam.transform.position + cam.transform.forward * 25;
    cubeVerts[2] = cam.transform.position + cam.transform.forward * 25;
    cubeVerts[3] = cam.transform.position + cam.transform.forward * 25;
    cubeVerts[4] = cam.transform.position + (cam.transform.right * -frustumHeight) + (cam.transform.up * frustumHeight) + (cam.transform.forward * maxDistance);
    cubeVerts[5] = cam.transform.position + (cam.transform.right * frustumHeight) + (cam.transform.up * frustumHeight) + (cam.transform.forward * maxDistance);
    cubeVerts[6] = cam.transform.position + (cam.transform.right * -frustumHeight) + (cam.transform.up * -frustumHeight) + (cam.transform.forward * maxDistance);
    cubeVerts[7] = cam.transform.position + (cam.transform.right * +frustumHeight) + (cam.transform.up * -frustumHeight) + (cam.transform.forward * maxDistance);

    for (int i = 0; i < edges.Length; i += 2)
    {
        Debug.DrawLine(cubeVerts[edges[i]], cubeVerts[edges[i + 1]], Color.red);
    }

在任何给定时间，更改后的视锥视图都会跟随相机。

在3D空间中获取与相机视图对齐的点

2 个答案: