Moving character in 2.5D platformer

[3DModelerMan]

Does anyone know of a good technique to make a player character move along the correct path? I had the level be where it just goes straight to the right. Now I'm redesigning it and it goes to the right then turns and goes back to normal then loops around (and there will be more of this later). I can't just move straight along the X-axis like I normally do.
Thanks .

[Virion]

i don't really understand...

[JP]

yeah not sure i understand either... maybe a picture would help?

what's your control scheme? it seems that you're going to be changing the axis the player moves along, will the controls change too?

[3DModelerMan]

It's a side scroller rendered in 3D like Kirby 64.
This is the path that he follows now, the red line shows his path and the black is platforms.

And this is what it should be.

[Virion]

oh... he means something like this: http://www.youtube.com/watch?v=AlsH_AH7CDs

that's the thing that i've been always wondering as well.

[trivtn]

I think Starcraft game is good example all he want.

[JP]

Might have to use some kind of waypoint graph to follow

[Dorth]

The way I've saw this coded before was as a line of node. Every point on the movement axis is either a node or in-between 2 nodes. You then only have to keep track of progression on said line to know your orientation. Look at heightmap, it'll give you some help.

[3DModelerMan]

Yeah that could be a good way. Would a trail of flat planes work so that I could move the character forward and the rotation of the character changes depending on the normal the raycast hit? Or is that inefficient?

[3DModelerMan]

I tried to figure out an implementation for this.

Code: Select all

if ( !path.empty() )
  {
   //Store Pingy's bounding box.
   aabbox3df pingyBB = mRenderMesh->getTransformedBoundingBox();
   vector3df lastPoint;
   vector3df currPoint;
   vector3df nextPoint;
   //Loop over list
   for (int i=0; i<path.size(); ++i)
   {
    //Check if point has been reached.
    if ( pingyBB.isPointInside( path[i]->getPosition() ) );
    {
     //Set the path points.
     if ( path[i-1] != NULL )
     lastPoint = path[i-1]->getPosition();
     if ( path[i] != NULL )
     currPoint = path[i]->getPosition();
     if ( path[i+1] != NULL )
     nextPoint = path[i+1]->getPosition();
     //Check for what side pingy is on.
     //=============================================
     if ( mRenderMesh->getPosition().X < path[i]->getPosition().X )
     {
      //Set new rotation.
      //=============================================
      vector3df toNext = mRenderMesh->getPosition()-nextPoint;
      vector3df newRot = toNext.getHorizontalAngle();
      mRenderMesh->setRotation(newRot);//(Or the controller empty)
      //=============================================
     }
     else
     {
      //Set new rotation.
      //=============================================
      vector3df toLast = mRenderMesh->getPosition()-lastPoint;
      vector3df newRot = toLast.getHorizontalAngle();
      mRenderMesh->setRotation(newRot);//(Or the controller empty)
      //=============================================
     }
    }
   }
  }

But for some reason it crashes.
I have the first and second scene nodes put in the path already.
What am I doing wrong?

[3DModelerMan]

Or maybe this psuedocode has the basic idea?

Code: Select all

if ( pointIsInBox(playerBB) )
{
 if ( playerPos > pointPos[i] && playerPos < pointPos[i+1] )
 //rotate.

 //do other side.
}

[grumpymonkey]

you could add invisible nodes at every turn and make the player face the direction of it for example:



you can use this function to get the angle between 2 points:

Code: Select all

double PointDirection(double x1, double y1, double x2, double y2){
   double angle=0;   
   angle=(atan2(x1-x2,y1-y2)*180)/3.14;
   return angle;
}


each node has the location of the next one so when the player reaches it, he gets the position of the next one, and faces that direction

[Josie]

Grumpymonkey is right. The best way I can think of is a node-based path. You can use splines if you want it to be extremely smooth. Interpolating between the points makes everything blend together. The camera will of course be rotated to face the current point between two nodes where the character is, and the location of the camera can be determined using cross products.