[Plib-users] ssgHOT question

[McEvoy, N. <nic...@ds...>]

Can anyone tell me why ssgHOT() returns different results depending on my
camera position (ie. 1st person view and external view) ?  In 1st person
view I get the correct HOT, when I change to an external view the HOT is
incorrect.  I get 2 hits when in 1st view (looking out over my terrain) and
4 hits when in external view (looking at my player which is sitting just
above the terrain).

In the method below getHeightAndNormal() my_position is always the player
pos (I'm not passing in the camera by mistake !)

Note: the same problem happens with ssgIsect().

What am I missing here ???

Is it something to do with the scene matrix ... causing some difference
within the ssgHOT() call ???

float
getHeightAndNormal(ssgRoot* scene, sgVec3 my_position, sgVec3 normal)
{
	/* Look for the nearest polygon *beneath* my_position */

	ssgHit *results;
	int num_hits;

	float hot;        /* H.O.T == Height Of Terrain */
	sgVec3 HOTvec;

	sgMat4 invmat;
	sgMakeIdentMat4(invmat);
	invmat[3][0] = - my_position [0];
	invmat[3][1] = - my_position [1];
	invmat[3][2] = 0.0;

	sgSetVec3(HOTvec, 0.0f, 0.0f, HIGHEST_HEAVEN);

	num_hits = ssgHOT(scene, HOTvec, invmat, &results);

	hot = DEEPEST_HELL ;

	for (int i = 0; i < num_hits; i++)
	{
		ssgHit *h = &results[i];

		float hgt = - h->plane[3] / h->plane[2];

		if (hgt >= hot)
		{
			hot = hgt;

			if (normal != NULL)
				sgCopyVec3(normal, h->plane);
		}
	}

	return hot;
}

Nick
http://members.ozemail.com.au/~ndmcevoy/