代码如下:
Vector3 screenPos = Input.mousePosition;
screenPos.z = 5.0f;
Vector3 p1 = Camera.main.ScreenToWorldPoint(screenPos);
Vector3 p0 = Camera.main.transform.position;
float h2 = 0.0f - p0.z;
float h1 = p1.z - p0.z;
Vector3 dir = p1 - p0;
dir.z = 0.0f;
float d1 = dir.magnitude;
float d2 = d1 * h2 / h1;
Vector3 p2 = p0 + dir.normalized * d2;
p2.z = 0;
示意图:
相似三角形原理。