// See if an object is in the view cone.
// Returns:
// 0 if object isn't in the view cone
// 1 if object is in cone
// This routine could possibly be optimized. Right now, for an
// offscreen object, it has to rotate 8 points to determine it's
// offscreen. Not the best considering we're looking at a sphere.
int obj_in_view_cone( object * objp )
{
int i;
vector tmp,pt;
ubyte codes;
// Use this to hack out player for testing.
// if ( objp == Player_obj ) return 0;
// OLD INCORRECT CODE!!!
// g3_rotate_vector(&tmp,&objp->pos);
// codes=g3_code_vector_radius(&tmp, objp->radius);
// if ( !codes ) {
// return 1; // center is in, so return 1
// }
// return 0;
// This I commented out because it will quickly out for
// objects in the center, but cause one more rotation
// for objects outside the center. So I figured it
// would be best to slow down objects inside by a bit
// and not penalize the offscreen ones, which require
// 8 rotatations to throw out.
// g3_rotate_vector(&tmp,&objp->pos);
// codes=g3_code_vector(&tmp);
// if ( !codes ) {
// //mprintf(( "Center is in, so render it\n" ));
// return 1; // center is in, so return 1
// }
// Center isn't in... are other points?
ubyte and_codes = 0xff;
for (i=0; i<8; i++ ) {
vm_vec_scale_add( &pt, &objp->pos, &check_offsets[i], objp->radius );
g3_rotate_vector(&tmp,&pt);
codes=g3_code_vector(&tmp);
if ( !codes ) {
//mprintf(( "A point is inside, so render it.\n" ));
return 1; // this point is in, so return 1
}
and_codes &= codes;
}
if (and_codes) {
//mprintf(( "All points offscreen, so don't render it.\n" ));
return 0; //all points off screen
}
//mprintf(( "All points inside, so render it, but doesn't need clipping.\n" ));
return 1;
}
//rotates a point. returns codes. does not check if already rotated
ubyte g3_rotate_vector(vector *dest,vector *src)
{
vector tempv;
Assert( G3_count == 1 );
MONITOR_INC( NumRotations, 1 );
vm_vec_sub(&tempv,src,&View_position);
vm_vec_rotate(dest,&tempv,&View_matrix);
return g3_code_vector(dest);
}
