How to handle cutscenes in XNA?

Question

I am making a 2D RPG in XNA, and I want to be able to have basic cutscenes, kinda like those in the handheld Pokemon games.

What is the easiest way to do this? Sorry for the vagueness of my question, but I'm new to game development, and nothing I've found says how to do this.

Answer 1

For in-game cutscenes scripting is usally used.

Take a look at Luainterface. The basic idea is that you expose functionality to Lua, and then use that to create cutscenes.

Here's a super basic sample where the camera moves over to a character, and then starts a script.

C#

lua = ScriptManager.createLua();
this.luafile = luafile;
lua.DoFile("scripts/" + luafile + ".lua");


lua.RegisterFunction("MoveCamera", this, GetType().GetMethod("MoveCamera"));
lua.RegisterFunction("SpawnChat", this, GetType().GetMethod("SpawnChat"));

lua.GetFunction("runScript").call();

Lua

function runScript()
{
    --pan camera to x100 and y 100 
    MoveCamera(x, y, CameraComplete); --last parameter is an onComplete function
}

function CameraComplete()
{
    SpawnChat("this is our hero ryan, isn't her handsome?");
}

Be sure to also check out Godpatterns: Scripting with Lua in C#

Answer 2

An easy way would be to keyframe objects in the scene using a basic keyframe data structure which can then be serialized to file (xml just a few lines of C#) and opened in a custom scene editor or edited by hand.

Replay should be very straight-forward -just deserialize the file and loop through the objects, showing and moving them whenever the keyframe timestamps passes the current cut scene time. Increase the current cut scene time using the game time. This way the cut scene can easily be scrubbed back and fourth, automatically paused and it's very easy to implement various kick-ass interpolation algorithms between keyframes.

class CutScene
{
    List<ScriptableObject> Objects;
    TimeSpan SceneLength;
    TimeSpan CurrentPosition;
}

// Anything that should show up, disappear, move or otherwise
// be scripted in the scene, like NPCs, text bubbles, other sprites, camera position
class ScriptableObject
{
    List<Keyframe> Keyframes;
}

class Keyframe
{
    TimeSpan TimeFromSceneStart;
    Vector2 Position;
    int Rotation;
}

With such a basic setup, multiple cut scenes could be played back at any time and also made to overlap. There are of course several ways to attach keyframes to in-game objects/classes...

Answer 3

I would create a class with multiple stages the progression to the next stage would dependant on a number of events occurring

pseudo code

stage 1:
//NPC1 starts talking

show text dialog();

if(dialogcompleted)
{
 _stage = 2;
}

stage 2:
//NPC1 walks to desk

npc.pos = MathHelper.Lerp(startpos,endpos,time/totaltime)

if(npc.pos = endpos)
{
_stage = 3;
}

etc

I have never used Lua so do not know if that option would be better, but this is how i would do it in pure C#.

Answer 4

You could use timing and use your input classes.

Pseudocode:

int runTime = 0;
Control.Input = null;
curTime = DateTime.Now;
while( runTime <  5000 ) {
  if( runTime < 1000 ) {
    Control.Target = NpcStore[0];
    Control.Event(KeyPress.Left);
    NpcStore[0].Say("I'm moving");
  }
  if( runTime > 1000 && runTime < 4000 ) {
    NpcStore[0].Say("I stopped!");
  }
  if( runTime > 4000 ) {
    NpcStore[0].Say("Cutscene ends soon.");
  }
  runTime = (DateTime.Now - curTime).MilliSeconds;
}
Control.Target = PlayerCharacter;
Control.Input = Keyboard;

If it's a "simple" project without modding capabilities, including a scripting engine is often overkill.