DBL Evaluate_Function_UV(FUNCTION funct, UV_VECT fnvec)
{
POVFPU_SetLocal(U, fnvec[U]);
POVFPU_SetLocal(V, fnvec[V]);
return POVFPU_Run(funct);
}
DBL Evaluate_Function(FUNCTION funct, VECTOR fnvec)
{
POVFPU_SetLocal(X, fnvec[X]);
POVFPU_SetLocal(Y, fnvec[Y]);
POVFPU_SetLocal(Z, fnvec[Z]);
return POVFPU_Run(funct);
}
void Evaluate_Function_Interval_UV(FUNCTION funct, DBL threshold, UV_VECT fnvec_low, UV_VECT fnvec_hi, DBL max_gradient, DBL& low, DBL& hi)
{
DBL f_0_0, f_0_1, f_1_0, f_1_1;
DBL f_0_min, f_0_max;
DBL f_1_min, f_1_max;
DBL junk;
/* Calculate the values at each corner */
POVFPU_SetLocal(U, fnvec_low[U]);
POVFPU_SetLocal(V, fnvec_low[V]);
f_0_0 = POVFPU_Run(funct) - threshold;
POVFPU_SetLocal(U, fnvec_low[U]);
POVFPU_SetLocal(V, fnvec_hi[V]);
f_0_1 = POVFPU_Run(funct) - threshold;
POVFPU_SetLocal(U, fnvec_hi[U]);
POVFPU_SetLocal(V, fnvec_low[V]);
f_1_0 = POVFPU_Run(funct) - threshold;
POVFPU_SetLocal(U, fnvec_hi[U]);
POVFPU_SetLocal(V, fnvec_hi[V]);
f_1_1 = POVFPU_Run(funct) - threshold;
/* Determine a min and a max along the left edge of the patch */
Interval( fnvec_hi[V]-fnvec_low[V], f_0_0, f_0_1, max_gradient, &f_0_min, &f_0_max);
/* Determine a min and a max along the right edge of the patch */
Interval( fnvec_hi[V]-fnvec_low[V], f_1_0, f_1_1, max_gradient, &f_1_min, &f_1_max);
/* Assume that the upper bounds of both edges are attained at the same
u coordinate and determine what an upper bound along that line would
be if it existed. That's the worst-case maximum value we can reach. */
Interval( fnvec_hi[U]-fnvec_low[U], f_0_max, f_1_max, max_gradient, &junk, &hi);
/* same as above to get a lower bound from the two edge lower bounds */
Interval( fnvec_hi[U]-fnvec_low[U], f_0_min, f_1_min, max_gradient, &low, &junk);
/*
char str[200];
static int its=0;
its++;
if (its>20) Error("Boom!");
sprintf( str, "%lf %lf %lf %lf %lf %lf %lf\n%lf %lf %lf %lf %lf %lf %lf %lf %lf %lf\n",
max_gradient,
fnvec_low[U], fnvec_low[V],
fnvec_hi[U], fnvec_hi[V],
fnvec_hi[U]-fnvec_low[U],
fnvec_hi[V]-fnvec_low[V],
f_0_0,f_0_1,f_1_0,f_1_1,
f_0_min,f_0_max,
f_1_min,f_1_max,
low,hi);
Warning( 0, str );
*/
/* f_min and f_max now contain the maximum interval. */
}