C# XNA 鼠标位置投影到 3D 平面 [英] C# XNA Mouse position projected to 3D plane

问题描述

我正在处理一个 3D XNA 项目，我已经考虑这个问题大约 2 周了.所以我决定问问你.

I'm working on a 3D XNA project, and I've been thinking about this problem for like 2 weeks. So I just decided to ask you.

基本上我有一个平面，我想将鼠标位置投影到那个平面上，但是如何呢?我尝试了很多方法来做到这一点，计算角度......但我发现，距离必须影响 X 位置，也许需要一些我以前从未听说过的数学运算.

Basically I have a flat plane and i want to project the mouse position to that plane, but how? I tried many ways to do it, calculated angles... But i figured out, that the distance must effect on the X position, maybe some math is needed what I've never heard before.

推荐答案

几年前我做了一些代码，返回位置为 Vector3(x,y,z)，给定鼠标状态:

I did some code few years ago which returns the position as Vector3(x,y,z), given mouse state:

private Vector3 FindWhereClicked(MouseState ms)
{
    Vector3 nearScreenPoint = new Vector3(ms.X, ms.Y, 0);
    Vector3 farScreenPoint = new Vector3(ms.X, ms.Y, 1);
    Vector3 nearWorldPoint = device.Viewport.Unproject(nearScreenPoint, cam.projectionMatrix, cam.viewMatrix, Matrix.Identity);
    Vector3 farWorldPoint = device.Viewport.Unproject(farScreenPoint, cam.projectionMatrix, cam.viewMatrix, Matrix.Identity);

    Vector3 direction = farWorldPoint - nearWorldPoint;

    float zFactor = -nearWorldPoint.Y / direction.Y;
    Vector3 zeroWorldPoint = nearWorldPoint + direction * zFactor;

    return zeroWorldPoint;
}

• device 是 GraphicsDevice 的一个实例.

希望它对你有用.

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