{"id":2281,"date":"2020-07-02T18:11:27","date_gmt":"2020-07-02T10:11:27","guid":{"rendered":"https:\/\/www.clonefactor.com\/wordpress\/?p=2281"},"modified":"2020-07-02T18:25:27","modified_gmt":"2020-07-02T10:25:27","slug":"put-shooting-marker-on-screen","status":"publish","type":"post","link":"https:\/\/www.clonefactor.com\/wordpress\/program\/c\/2281\/","title":{"rendered":"Put shooting marker on screen."},"content":{"rendered":"\n

When we want to make a on screen marker to identify the shooting target on screen.
basically we asking “how to convert World position into UGUI screen position in term of RectTransform anchor.”<\/p>\n

\"\"<\/p>\n

Technically speaking it’s a space convert issue.
in this case assume we following Object in the scene :<\/p>\n

    \n
  1. m_WorldPosition<\/strong> : the target position we wanted to display but in 3D world space (perhaps the raycast hit point?!)<\/li>\n
  2. m_ViewCamera<\/strong> : a camera for player to explore virtual world. (upper camera)<\/li>\n
  3. m_UICamera<\/strong> : a camera only culling UI overlayer (camera only for UI)<\/li>\n
  4. m_MarkerRect<\/strong> : the RectTransform based on UGUI Canvas. (the MARKER)<\/li>\n<\/ol>\n

    so here is what we wanted to do :<\/p>\n

      \n
    1. first we need to convert the world position (<\/span>m_WorldPosition<\/strong>) from “m_ViewCamera<\/strong>” into the screen position<\/span><\/li>\n
    2. and then use that screen position based on “m_UICamera<\/strong>” matrix, convert onto UGUI RectTransform anchorPosition<\/li>\n<\/ol>\n

      so the code will look like this.<\/p>\n

      \/\/ assume we had following\n\/\/ RectTransform m_MarkerRect;\n\/\/ Camera m_ViewCamera;\n\/\/ Camera m_UICamera;\n\/\/ Vector3 m_WorldPosition;\n\nVector3 screenPos = m_ViewCamera.WorldToScreenPoint(m_WorldPosition);\nbool withInParentRect = RectTransformUtility.ScreenPointToLocalPointInRectangle((RectTransform)m_MarkerRect.parent, screenPos, m_UICamera, out Vector2 anchorPos);<\/pre>\n
      we used following API.<\/p>\n