/************************************************************************\
*  This subroutine modifies the centroid of the truncation function.     *
*  There is a complicated scheme to assign the centroid to the           *
*  truncation function because it may have its own centroid, or it may   *
*  take on the centroid of the object that it is modifying.  And         *
*  because multiple objects are allowed to use the same truncation       *
*  function, the centroids may all be different even though all the      *
*  remaining parameters are shared by all the profile functions.         *
*                                                                        *
*  This is normally not such a big issue except when a PSF is            *
*  oversampled: the centroids have to be shifted/expanded relative to    *
*  the main galaxy profile component.                                    *
\************************************************************************/

#include <string.h>
#include "structs.h"

int istrunc (char *objtype);

void trunc_cent (struct fitpars *mod, struct fitpars *orig, float *refpos,
    int os)
{
    struct fitpars *new_trunc, *orig_tr;

    orig_tr = orig->high;   /* Point to the original fpar->high structure  */
			    /* to look for truncation funcstions.          */

    new_trunc = mod->high;  /* Point to the temporary fpar->high structure */
			    /* created to store parameters modified for    */
			    /* oversampling and convolution.               */

    while (new_trunc != NULL) {
	if (istrunc (new_trunc->objtype)) {

	    /*-------------------------------------------------------------\
	    |  If the truncation function doesn't have its own position,   |
	    |  then it is centered on the function it's truncating by      |
	    |  setting ia = 3.  Note that this is set only in the copy     |
	    |  of fpar, not in the original fpar.  If it's set in the      |
	    |  original fpar, then df work arrays would be created for     |
	    |  these components, which is bad news.                        |
	    \-------------------------------------------------------------*/

	    if (orig_tr->ia[1] == -1 || orig_tr->ia[2] == -1) {
	        new_trunc->a[1] = refpos[1];
	        new_trunc->a[2] = refpos[2];
		new_trunc->ia[1] = 3;
		new_trunc->ia[2] = 3;
	    };

	    /*-------------------------------------------------------------\
	    |  If the truncation function has its own position, then all   |
	    |  we have to do is figure out how it relates to the model     |
	    |  function it is truncating.                                  |
	    \-------------------------------------------------------------*/

	    if (orig_tr->ia[1] >= 0 || orig_tr->ia[2] >= 0) {
	        new_trunc->a[1] = (orig_tr->a[1] - orig->a[1]) * os + 
				  				refpos[1];
	        new_trunc->a[2] = (orig_tr->a[2] - orig->a[2]) * os + 
								refpos[2];
	    };
	};
	orig_tr = orig_tr->next;
	new_trunc = new_trunc->next;
    };
}