實現

Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
if (Physics.Raycast(ray, out RaycastHit hit))
{textureCoord = hit.textureCoord;textureCoord.x *= textureMat.width;textureCoord.y *= textureMat.height;textureColor = textureMat.GetPixel(Mathf.FloorToInt(textureCoord.x), Mathf.FloorToInt(textureCoord.y));
}

*貼圖和物體的Read/Write Enabled 都需處于開啟狀態，貼圖的Use Crunch Compression 需處于關閉狀態。

效果

*右側為世界中的3d 物體，左側為Canvas 上的Image?