nimforum mirror - llegal capture 'world' because ':anonymous' has the calling convention: <cdecl>

mantielero (orginal) [2020-05-13T09:35:02+02:00] view original

I am trying to define the following callback from Nim:


static void nearCallback (void *data, dGeomID o1, dGeomID o2)
{
  int i;
  
  //-- Get the body's ID
  dBodyID b1 = dGeomGetBody(o1);
  dBodyID b2 = dGeomGetBody(o2);
  
  //-- If they are connected by a joint, no collision detection is done. Finish
  if (b1 && b2 && dAreConnectedExcluding (b1,b2,dJointTypeContact)) {
    return;
  }
  
  //-- Configure the properties for the contact points
  dContact contact[MAX_CONTACTS];
  for (i=0; i<MAX_CONTACTS; i++) {
    contact[i].surface.mode = dContactBounce | dContactSoftCFM;
    contact[i].surface.mu = MU;
    contact[i].surface.mu2 = MU2;
    contact[i].surface.bounce = BOUNCE;
    contact[i].surface.bounce_vel = BOUNCE_VEL;
    contact[i].surface.soft_cfm = SOFT_CFM;
  
  }
  
  //-- Get the contact points
  int numc = dCollide (o1,o2,MAX_CONTACTS,&contact[0].geom, sizeof(dContact));
  
  //-- If there are at least one contact point...
  if (numc!=0) {
    
    //-- For every contact point a joint should be created
    for (i=0; i<numc; i++) {
      
      //-- Create the joint and add it to the contact group
      dJointID c = dJointCreateContact (world,contactgroup,&contact[i]);
      
      //-- Set the articulation between the two bodies
      dJointAttach (c,b1,b2);
    }
  }
}

In the C example, both world and contactgroup are global.

I tried to define this callback using a closure like this:

proc genNearCallBack(world:dWorldID, contactgroup:dJointGroupID):dNearCallback =
  let world = world
  let contactgroup = contactgroup
  return proc( data:pointer, o1,o2:dGeomID) {.exportc,cdecl.} =
    #[
    Callback function invoked by the dSpaceCollide function when two objects
    are about to collide
    The contact points should be found and a special contact joints should be
    added. After that simulation step, the contact joints should be removed
    ]#
    # Get the body's ID
    var b1 = dGeomGetBody(o1)
    var b2 = dGeomGetBody(o2)
    
    # If they are connected by a joint, no collision detection is done. Finish
    if b1 != nil and b2 != nil and (dAreConnectedExcluding(b1,b2,dJointTypeContact.cint) == 1):
      discard ""
    else:
      # Configure the properties for the contact points
      var contact = newSeq[dContact]( MAX_CONTACTS )
      for i in 0..<MAX_CONTACTS:
        contact[i].surface.mode = dContactBounce.cint + dContactSoftCFM.cint  #dContactBounce | dContactSoftCFM
        contact[i].surface.mu = MU
        contact[i].surface.mu2 = MU2
        contact[i].surface.bounce = BOUNCE
        contact[i].surface.bounce_vel = BOUNCE_VEL
        contact[i].surface.soft_cfm = SOFT_CFM
      
      # Get the contact points
      let numc = dCollide(o1, o2, MAX_CONTACTS, contact[0].geom.unsafeAddr, sizeof(dContact).cint)
      
      # If there are at least one contact point...
      if numc != 0:
        # For every contact point a joint should be created
        for i in 0..<numc:
          # Create the joint and add it to the contact group
          var c = dJointCreateContact(world,contactgroup,contact[i].unsafeAddr)
          
          # Set the articulation between the two bodies
          dJointAttach(c,b1,b2)

and I am getting the mentioned error:


Error: illegal capture 'world' because ':anonymous' has the calling convention: <cdecl>

It is simply not possible or to do it because of the calling convention or is it that I am not doing the closure properly?

Cheers

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6328 :: llegal capture 'world' because ':anonymous' has the calling convention: <cdecl>