RaycastHit.textureCoord2

描述

撞击点处的辅助 UV 纹理坐标。

这可以用于 3D 纹理绘制或绘制弹痕。 如果碰撞体不是网格碰撞器，则返回 Vector2.zero。 如果网格不包含任何辅助 UV 集，则返回主 UV 集的 UV。

using UnityEngine;

public class Example : MonoBehaviour
{
    // Attach this script to a camera and it will paint black pixels in 3D
    // on whatever the user clicks. Make sure the mesh you want to paint
    // on has a mesh collider attached.

    Camera cam;

    void Start()
    {
        cam = GetComponent<Camera>();
    }

    void Update()
    {
        // Only when we press the mouse
        if (!Input.GetMouseButton(0))
        {
            return;
        }

        // Only if we hit something, do we continue
        RaycastHit hit;
        if (!Physics.Raycast(cam.ScreenPointToRay(Input.mousePosition), out hit))
        {
            return;
        }

        // Just in case, also make sure the collider also has a renderer
        // material and texture. Also we should ignore primitive colliders.
        Renderer rend = hit.transform.GetComponent<Renderer>();

        MeshCollider meshCollider = hit.collider as MeshCollider;

        if (rend == null || rend.sharedMaterial == null ||
            rend.sharedMaterial.mainTexture == null || meshCollider == null)
        {
            return;
        }

        // Now draw a pixel where we hit the object
        Texture2D tex = rend.material.mainTexture as Texture2D;
        Vector2 pixelUV = hit.textureCoord2;
        pixelUV.x *= tex.width;
        pixelUV.y *= tex.height;

        tex.SetPixel(Mathf.FloorToInt(pixelUV.x), Mathf.FloorToInt(pixelUV.y), Color.black);

        tex.Apply();
    }
}