Editing mission briefings is similar to that of editing triggers. Trigger editing requires a player, condition, and action. Mission briefings only require a player and action. A few actions can be carried out:
Display Speaking Portrait
Makes one of the four portraits at the top begin its speaking (or moving) animation cycle for a set amount of time. You must have the portrait first shown (see SHOW PORTRAIT) for this to work.
Makes one of the four portraits at the top disappear. You must have the portrait first shown (see SHOW PORTRAIT) for this to work.
Changes the mission objective box at the bottom left corner to your desired text. Note that this does not refer to the mission objectives box in the game, rather only the mission objectives box in your mission briefing prescreen is affected.
Plays a given sound.
Reveals the portrait of a desired unit in one of the four portrait slots.
Displays a given text message for a set amount of time. Should be coupled with the WAIT function as the briefing duration does not count the time the message it to be displayed (i.e. the briefing may end before displaying the text for the set amount of time if the wait period is less than the time the message is to be displayed). Also the text message will scroll downwards if the message exceeds the length that can fit in the box. The scroll speed can be adjusted by lengthening or shortening the text display time (slower speeds by increasing display time and vice versa). Note that there is a max speed the text can scroll and if too large a message is shown in too small a time, the message will be truncated.
This is a combo of the DISPLAY SPEAKING PORTRAIT, PLAY WAV, and TEXT MESSAGE functions. However you must still remember to SHOW PORTRAIT first in a separate action.
This function allows you to determine the length of the entire mission briefings as well as set pauses between transmissions.
Remember that having actions set for any number of time without any "WAIT" action itself, the mission briefing will simply end and nobody will see what you've done.