[SOLVED}Help with moving a character

[kohaar]

Hi. I'm trying to move a character to a specified position, similar to waypoints, but the character seems to move in an entirely different position than the one specified. Can you please look through the code and see if you can give me any pointers.

Most of the code is from this example: http://irrlicht.sourceforge.net/phpBB2/ ... hp?t=12238

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    // Current possition
	float tx0 = node_zombie->getPosition().X;
	float tz0 = node_zombie->getPosition().Z;
	// Moveto position
	float tx1 = movepos.X;
	float tz1 = movepos.Z;
	
	// Rotation of character and heading
	float a = abs(tz1-tz0);
	float b = abs(tx1-tx0);
	float c = sqrt( pow(a,2) + pow(b,2) );
	float rotation = sin(a/c);
	rotation *= (180/PI);
	node_zombie->setRotation(vector3df(0,rotation,0));
	
	// Translation position
    tPos.Z=(float)cos(rotation*(PI/180))*4.1f;
	tPos.X=-(float)sin(rotation*(PI/180))*4.1f;

	// Tryout collision
	dPos = CGameMain::getSceneManager()->getSceneCollisionManager()->getCollisionResultPosition(CCollision::getCollision(), 
	       oldPos, vector3df(10.0f,10.0f,10.0f), tPos, triout, gravity, 0.05f, vector3df(0.0f,-3.0f,0.0f));
  
	// Setposition
	node_zombie->setPosition(dPos);

[bitplane]

its much simpler to deal with vectors as whole units, rather than breaking them into x,y and z and using trig.

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  // u32 timeSinceLastLoop is the number of ms since the last animation frame
  // f32 speed is in units per ms 
  f32 distance = (f32)timeSinceLastLoop * speed;
  vector3df direction(0,0,1); // the direction your node is facing
  pos = node->getPosition();
  node->getRelativeTransformation().rotateVect(direction);
  pos += direction * distance;
  node->setPosition(pos);

[kohaar]

I'm not sure what you mean by dealing with the vector as a whole unit?

If I have a position that I want to move to, and I want to change the direction in comparison to the current position, I need trig, don't I?

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                  Destination

                / |
              /   |
            /     |
          /       |
        /         |
        ---------
  Current pos

Also I need collision detection, since I am moving my character through a b3d terrain.

[bitplane]

ah, i see. you still don't need to mess about with trig though, the vector class does it all for you.

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// to get the direction
vector3df direction = (destination-pos).normalize();
// to get the angle-
f32 angle = direction.getHorizontalAngle();

[kohaar]

Your my hero. It works like a charm! Thanks.

Here is the working code, if anyone should encounter similar problems.

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// Move an object to a destination. vector3df movepos is the destination
void CZombie::move()
{
   vector3df oldPos = node_zombie->getPosition();;
   vector3df tPos;
   triangle3df triout; 
   bool gravity = true;

   if(oldPos.getDistanceFrom(movepos) >= 100)
   {
	  vector3df direction = (movepos-oldPos).normalize();
	  
	  // The minus 90 could be that my character is rotated on import
	  f32 angle = direction.getHorizontalAngle().Y-90;

	  node_zombie->setRotation(vector3df(0,angle,0));
	
	  // Translation position - Movement should be framerate independent. 
      tPos.Z=direction.Z*4.1f;
	  tPos.X=direction.X*4.1f;

	  // Tryout collision - CCollision getcollision is the triangleselector for the environment
	  vector3df dPos = CGameMain::getSceneManager()->getSceneCollisionManager()->getCollisionResultPosition(CCollision::getCollision(), 
	       oldPos, vector3df(10.0f,10.0f,10.0f), tPos, triout, gravity, 0.05f, vector3df(0.0f,-3.0f,0.0f));
  
	  // Setposition
	  node_zombie->setPosition(dPos);

	  waypoint = false;
   }
   else
   {
	   waypoint = true;
   }
}

[Nox587]

Looks like a pretty good solution, curious about one thing though:

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   // Translation position - Movement should be framerate independent.
      tPos.Z=direction.Z*4.1f;
     tPos.X=direction.X*4.1f; 

Your comment says movement should be framerate independent, but you are multiplying by a constant.

If you want 4.1 to be your speed you should multiply it by the frame time.

biplane's first bit of code shows this:

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// u32 timeSinceLastLoop is the number of ms since the last animation frame
  // f32 speed is in units per ms
  f32 distance = (f32)timeSinceLastLoop * speed; 

This thread also has some good information regarding frame rate independant movement:
http://irrlicht.sourceforge.net/phpBB2/ ... .php?t=723