Create_Mission: You must not go to Z'ha'dum

[teleportationwars]

You must not go to Z'ha'dum, or how we made missions work without all those scary GM_ libraries.

Vanilla uses a tortured system of nested libraries to manage the mission system. A large part of said said system boils down to an unweighted do_any.

We did not wish to copy that format.

Here is a small example of a multi-step mission:

Code: Select all

<cue name="MissionSignaller">
    <actions>
        <find_station name="$Station" space="player.sector" multiple="false" />
        <signal_cue_instantly cue="DockMissionOfferCue" param="$Station" />
    </actions>
</cue>
<cue name="DockMissionOfferCue" instantiate="true" namespace="this">
    <conditions>
        <event_cue_signalled />
    </conditions>
    <actions>
        <set_value name="$BaseCue" exact="this" />
        <create_cue_actor cue="this" actor="event.param.controlentity.{controlpost.manager}" />
        <create_offer cue="DockMissionOfferCue" name="'Dock Mission (Test)'" difficulty="level.trivial" reward="500Cr" actor="event.param.controlentity.{controlpost.manager}" associated="event.param" description="'foo'" faction="faction.argon">
            <briefing>
                <objective step="1" action="objective.flyto" object="event.param" />
                <objective step="2" action="objective.talkto" object="event.param.controlentity.{controlpost.manager}" />
            </briefing>
        </create_offer>
    </actions>
    <cues>
        <cue name="DockMissionCue">
            <conditions>
                <event_object_signalled object="this.parent.actor" param="'accept'" />
            </conditions>
            <actions>
                <create_mission cue="this" offercue="DockMissionOfferCue"></create_mission>
                <set_objective cue="this" step="1" action="objective.flyto" object="this.parent.actor.assignedcontrolled" />
                <remove_offer cue="this.parent" />
            </actions>
            <cues>
                <cue name="DockEventListener">
                    <conditions>
                        <event_object_docked_at container="$BaseCue.actor.assignedcontrolled" />
                        <check_value value="event.param == player.ship" />
                    </conditions>
                    <actions>
                        <set_objective cue="this.parent" step="2" action="objective.talkto" object="$BaseCue.actor" />
                    </actions>
                </cue>
                <cue name="TalkEventListener">
                    <conditions>
                        <check_any>
                            <event_conversation_started conversation="default" actor="$BaseCue.actor" />
                        </check_any>
                    </conditions>
                    <actions>
                        <remove_mission cue="this.parent" type="completed" />
                        <transfer_money from="faction.argon" to="faction.player" amount="500Cr" />
                    </actions>
                </cue>
                <cue name="AbortListener">
                    <conditions>
                        <event_mission_aborted cue="this.parent" />
                    </conditions>
                    <actions>
                        <remove_mission cue="this.parent" type="aborted" />
                        <cancel_cue cue="$BaseCue" />
                    </actions>
                </cue>
            </cues>
        </cue>
    </cues>
</cue>

This gives the player an offer to dock at a station (in their current sector) and speak to the station manager, for a reward of 500Cr.


There are a few poorly expressed, but very essential patterns here.

Keeping Offers and Missions Alive:

• offer and mission cues require child cues to maintain the offer or mission, or it will just disappear when the cue completes its actions.

• we overcome this in the example by creating the mission as a child of the offer cue, and the event listeners act as children of the mission.

Cue Actor:

• each mission offer requires an actor to interact with the UI. This can be a generic cue actor, or (as in our case) an NPC involved in the mission itself; it doesn't really matter who it is. We set the NPC as the cue actor for ease of reference through the rest of the code, but this may not be required.

Accepting an Offer:

• event_object_signalled object="this.parent.actor" param="'accept'" comes all the way from lua. It is the signal created when you click the "Accept" button on a mission offer.

Removing Offers and Missions:

• remove_offer and remove_mission are the only way to get them out of your UI without cancelling the cues.

Some additional points to keep in mind:

Creating a Mission Group:

• add an entry to missiongroups.xml, then include group="missiongroup.GROUPIDHERE" in your create_offer

• using location on the mission offer will override the mission group

Setting a Location to Pick Up the Offer:

• use both the location (station, or supposedly ship?) and distance attributes on your create_offer

• the space attribute will also limit the area in which you can see an offer, but it does not create an icon on the map or at a specific station

• the offer will not automatically disappear if you fly away, and there isn't a natural timeout either; you'll have to insert additional code to make that happen

Rewards are not Automatic:

• you must transfer money to the player upon completion of the mission

• the rewardtext attribute on create_offer allows you to insert your own reward text string. Just replace the transfer_money line with add_inventory or whatever you want to do instead.

Mission Threads Exist:

• like the mentor mission series, you can use the mission_thread stuff to make missions that pop up one after each other, but we have not explored that too deeply yet.

Missions Do Not Need Offers:

• create_mission can reference an offercue like we did in the example above to steal its attributes, or you can include many of the same attributes from create_offer on create_mission instead, and just give the player a mission without making them click on anything.

Aborting Missions:

• remember to cancel the $BaseCue when aborting a mission, or else it doesn't actually stop listening for you to complete the objectives.

[h2odragon3]

Thank you very much for this. Perhaps it could be linked in the resources sticky too?