Re: [Plib-devel] ssgaSpheres?

[Bram S. <br...@sa...>]

On 02/02/05 09:30:56, Steve Baker wrote:

> If you follow that tortured explanation then you'll see that the
> bounding
> sphere for a sphere is not an exact fit for the sphere.

Steve,

This is not the problem.
As I said, the spheres are also visually wrong.
If you render both styles, they have different sizes.
And both sizes are also a mismatch against a sgSphere
with radius 1, judging from the hits I get from sgIsect()
(although this latter problem could be a bug in my isect program).

Rendering this scenegraph:

  scene    =3D new ssgRoot      ;
  balltrf0  =3D new ssgTransform ;
  balltrf1  =3D new ssgTransform ;

  ball0 =3D new ssgaSphere();
  ball1 =3D new ssgaSphere();

  ball0->setLatLongStyle(FALSE);
  ball0->setSize(1.0);
  ball0->setColour(blu);

  ball1->setLatLongStyle(TRUE);
  ball1->setSize(1.0);
  ball1->setColour(red);

  scene->addKid(balltrf0);
  scene->addKid(balltrf1);

  balltrf0->addKid(ball0);
  balltrf1->addKid(ball1);

  sgVec3 pos0=3D{-1,0,0};
  sgVec3 pos1=3D{ 1,0,0};
  balltrf0->setTransform(pos0);
  balltrf1->setTransform(pos1);

  ssgSimpleState *state =3D new ssgSimpleState();
  state->setShininess(8.0);
  ball0->setKidState(state);
  ball1->setKidState(state);

  sgCoord campos ;
  sgSetCoord ( & campos, 0.0f, -5.0f, 1.0f, 0.0, 0.0f, 0.0f ) ;
  ssgSetCamera ( & campos ) ;

Will give you the output as can be seen in attached jpeg.
This is clearly wrong. Changing topology of the sphere should
not affect size. I also expect the mismatch against sgSphere.
I have some isect test prog if you want that.

Also, you have to make a decision on the definition of ssgaSphere
of size 1: do you want its radius to be 1, or its diameter? From
what I'm seeing: neither sphere style has neither radius 1 nor
diameter 1, judging from isects with sgSphere radius 1.

   Bram