Picking

[Chris Bolduc]

I am trying to set up picking for collision detection, but it doesn't
work at all.

I declared a PickTool at the top of my World:
protected PickTool picker;

Next, I set all of the shapes I want to pick from to be pickable:
shape3d.setPickable(true);

Then I try picking:

public void doPicking() {
picker.setShapeRay(p_eye, velocity);
PickResult picked = picker.pickClosest();
if (picked != null) {
velocity.z = 0;
velocity.x = 0;
}
else {
return;
}
PickIntersection intersect = picked.getIntersection(0);
Point3d nextpoint = intersect.getPointCoordinates();
}

This is from a tutorial at http://www.benmoxon.info/Java3d/purple7.htm.

Nothing happens when there is a collision. The PickResult is always
null. What am I doing wrong?

[W. Wood Harter]

Do you get an exception?

Here is one of my picking routines from fps370. This checks the camera movement. The ball movement is verysimilar but more complex after it has a result as it  has to calculate the bounce.

    if (pickTool == null)

    {

      // create the picktool to always use the map

      pickTool = new PickTool (bgMap);

    }

     

    // set the shape of the pick tool as a ray from the current location

    // in the direction of the move

    pickTool.setShapeRay( new Point3d (vViewPos.x,vViewPos.y,vViewPos.z),

                       new Vector3d (vMove.x,vMove.y,vMove.z));

   

    // get a pick to the closest shape

    PickResult res = pickTool.pickClosest();

   

    // if we got a result, check for the closest intersection distance

    if (res != null)

    {

      int j;

      float closestIntersect = Double.MAX_VALUE ; // a big number just in case

      for (j = 0 ;j < res.numIntersections();j ++ )

      {

        if ((j == 0 ) || (res.getIntersection(j).getDistance() < closestIntersect))

          closestIntersect = ( float ) res.getIntersection(j).getDistance();

      }

      if (closestIntersect < 2.0 )

      {

        // collision, adjust accordingly

        vMove.set( 0.0f , 0.0f , 0.0f );

        return true;

      }      

    }    

I also had a lot of trouble with setPickable. It didn't work for me, but it gave an exception and that is why I asked about exceptions. This is what I had to use instead of setPickable.

        PickTool.setCapabilities((Shape3D)o,PickTool.INTERSECT_COORD);

 

Wood

--
http://www.memorize-it.com

---

From: "Chris Bolduc" <chris....@gmail.com>
Sent: Tuesday, May 16, 2006 11:28 AM
To: "GameDev370" <GameD...@googlegroups.com>
Subject: [GameDev370] Picking

[Chris Bolduc]

Gaaah! Formatting! I fixed it for you:

/**
* Does picking
* @see http://www.benmoxon.info/Java3d/purple7.htm
* @return true if something was picked
*/
public boolean doPicking() {
if (pick_tool == null) {
// create the pick_tool to always use the map
pick_tool = new PickTool(bgMain);

}
// set the shape of the pick tool as a ray from the current location
// in the direction of the move

pick_tool.setShapeRay(p_eye, velocity);

// get a pick to the closest shape

PickResult res = pick_tool.pickClosest();

// if we got a result, check for the closest intersection distance
if (res != null) {

float closestIntersect = Float.MAX_VALUE;

// a big number just in case

for (int j = 0;j < res.numIntersections(); j++) {

if ( (j == 0) || (res.getIntersection(j).getDistance() <

closestIntersect) ) {
closestIntersect = (float) res.getIntersection(j).getDistance();
}
}
if (closestIntersect < 2.0) {
// collision, adjust accordingly
}
return true;
}
return false;
}

[W. Wood Harter]

What did you fix? The version I sent you is working fine for me.

Wood

--
http://www.memorize-it.com

---

From: "Chris Bolduc" <chris....@gmail.com>

Sent: Tuesday, May 23, 2006 3:16 PM
To: "GameDev370" <GameD...@googlegroups.com>
Subject: [GameDev370] Re: Picking

[Darrell Noice]

wood, albeit clean in email, on the groups page, the code you presented
had tons of whitespace interlaced in it making it rather difficult to
read, that's all.

[berm...@chapman.edu]

---------------------------- Original Message ----------------------------
Subject: [GameDev370] Re: Picking
From: "Chris Bolduc" <chris....@gmail.com>
Date: Tue, May 23, 2006 3:15 pm
To: "GameDev370" <GameD...@googlegroups.com>
--------------------------------------------------------------------------

Gaaah! Even more evil Formatting! I fixed it for you: