1 Topic by Conard (edited by Conard 2007-04-14 10:09:22)

  • Registered: 2007-04-09
  • Posts: 12

Topic: Line3df

I'm trying to make a function that gets me the height of an ITriangleSelector at a certain point.
I found this function posted somewhere on the Irrlicht forums:

float GetHeight(irr::IrrlichtDevice *device,scene::ITriangleSelector *Ground, const vector3df& pos, float maxHeight) { 

    scene::ISceneCollisionManager* colMan = device->getSceneManager()->getSceneCollisionManager(); 

    vector3df yAxis(0,maxHeight,0); 

    line3d<f32> ray(pos, pos-yAxis); 

    vector3df ptoCol(0,0,0); 

    triangle3df triangle; 

    if(colMan->getCollisionPoint(ray, Ground, ptoCol, triangle)) { 

        return ptoCol.Y; 

        } 

        else 

        { 

        return -maxHeight; 

        } 
}

This is what I came up with, trying to convert it:

Function getHeight:Float(dev1:IrrlichtDevice , ground:ITriangleSelector , pos:vector3df , maxHeight:Float)
    Local colMan:ISceneCollisionManager = dev1.getSceneManager().getSceneCollisionManager()
    Local yAxis:vector3df = (_VECTOR3DF(0 , maxHeight , 0))
    Local tmppos:vector3df = (_VECTOR3DF(pos.getX() , pos.getY() - yAxis.getY() , pos.getZ()))
    Local ray:line3df
     ray.createFromVects(pos , tmppos)
    Local ptoCol:vector3df = (_VECTOR3DF(0, 0, 0))
    Local triangle:triangle3df = New triangle3df
    
    If(colMan.getCollisionPoint(ray , ground , ptoCol , triangle)    )
        Return ptoCol.getY()
    Else
        Return maxHeight
    EndIf
EndFunction

The colMan.getCollisionPoint functions, is supposed to get the collision between a line3df (ray) and an ITriangleSelector (ground) and return the collision point in a vector3df (ptoCol) and the triangle the collision is on as a triangle3df (triangle).

When I try this function out, it gives me an error, saying that "If(colMan.getCollisionPoint(ray , ground , proCol , triangle))" is trying to access a field or method of a NULL object.

When I look in the Debug tab of the Bmax IDE it says that 'Local ray:Line3df=Null'.
When I add " = New line3df" behind "Local ray:line3df", it will compile, but when the program starts it will give me an error saying that te program stopped unexpected.

I would appreciate it if someone could help me out with this.

Thanks in advantage.

  • gman
  • Administrator
  • Offline
  • Registered: 2006-01-04
  • Posts: 764

Re: Line3df

a couple things.  try changing the following lines from:

 Local ray:line3df
     ray.createFromVects(pos , tmppos)
    Local triangle:triangle3df = New triangle3df

to

 Local ray:line3df=Line3df.createFromVects(pos , tmppos)
 Local triangle:triangle3df = triangle3df.create()

both ray and triangle need an actual instance in C++ to be created.  where in just BMAX you can do a new, in the Irrlicht mod (because its a wrap) you have to use a create function or an _ function to get an actual instance.

HTH

  • Registered: 2007-04-09
  • Posts: 12

Re: Line3df

Thanks, works like a charm smile.