ZDoom

You see I've got this huge problem. It's a single swinging door. They're opening as they should but everytime you open them it displays a message "Invalid mirror polyobj num 16 for polyobj num 2. I don't know how to overcome this. My other project had the same problem but it's gone now so I've copied everything exactly from my other project to the new one and i'm getting the same error message over again. It's really annoying. It seems that Gzdoom (1.71..) takes "speed number" from "7. swing door definition". My door's opening speed is 16 when I changed it to 10. It prints the same message but this time mirror polyobj num 10 not 16.

A demo map would help us a lot.

Caleb26 wrote:You see I've got this huge problem. It's a single swinging door. They're opening as they should but everytime you open them it .....

First you start out by saying 'It's a single swinging door.' and then go on to talk in the plural and
mention 'mirror'. So, I assume that you mean a two part swinging door.

An excellent tutorial can be found in the wiki:
http://zdoom.org/wiki/Polyobject

Just a quick overview:
Polyobject Start Spots (9301) and Polyobject Anchors (9300) are assigned a specific number with Angle.
So, Angle is not something degrees, but identifies the location of where a Polyobject is located and
where it moves.

A swinging door could consist of two polyobjects, for example, a left side (Angle 1) and a right side (Angle 2).

Then each polyobject has a Startline, which assigns the ID to the polyobject and also specifies the mirrored
part. So, the Startline of the left side specifies polyobject 1 and mirror 2. The Startline of the right
polyobject specifies polyobject 2. Because it is already mirrored, specifying mirror 1 is not really required,
but does no harm.

7:Polyobj_DoorSwing (po, speed, angle, delay)

The polyobject door can be triggered by attaching the polyobject swing special directly to a linedef of the
polyobject, which opens with 'use' when the player stands before the door, or it could be a walk-over linedef
or a switch or a script.

Example for Polyobj_DoorSwing

Well, I wouldn't use Polyobj_DoorSwing, because you can also solve the swinging door problem with scripts.