/*
 * jittered.c
 *
 * Copyright (C) 1989, 1991, Craig E. Kolb
 * All rights reserved.
 *
 * This software may be freely copied, modified, and redistributed
 * provided that this copyright notice is preserved on all copies.
 *
 * You may not distribute this software, in whole or in part, as part of
 * any commercial product without the express consent of the authors.
 *
 * There is no warranty or other guarantee of fitness of this software
 * for any purpose.  It is provided solely "as is".
 *
 * $Id: jittered.c,v 4.0 91/07/17 14:34:43 kolb Exp Locker: kolb $
 *
 * $Log:	jittered.c,v $
 * Revision 4.0  91/07/17  14:34:43  kolb
 * Initial version.
 * 
 */
#include "light.h"
#include "jittered.h"

static LightMethods *iJitteredMethods = NULL;

Jittered *
JitteredCreate(pos, e1, e2)
Vector *pos, *e1, *e2;
{
	Jittered *j;

	j = (Jittered *)share_malloc(sizeof(Jittered));

	j->pos = *pos;
	j->e1 = *e1;
	j->e2 = *e2;

	return j;
}

LightMethods *
JitteredMethods()
{
	if (iJitteredMethods == (LightMethods *)NULL) {
		iJitteredMethods = LightMethodsCreate();
		iJitteredMethods->intens = JitteredIntens;
		iJitteredMethods->dir = JitteredDirection;
	}
	return iJitteredMethods;
}

int
JitteredIntens(jit, lcolor, cache, ray, dist, noshadow, color)
Jittered *jit;
Color *lcolor, *color;
ShadowCache *cache;
Ray *ray;
Float dist;
int noshadow;
{
	return !Shadowed(color, lcolor, cache, ray, dist, noshadow);
}

void
JitteredDirection(lp, pos, dir, dist)
Jittered *lp;
Vector *pos, *dir;
Float *dist;
{
	/*
	 * Choose a location with the area define by corner, e1
	 * and e2 at which this sample will be taken.
	 */
	VecAddScaled(lp->pos, nrand(), lp->e1, &lp->curpos);
	VecAddScaled(lp->curpos, nrand(), lp->e2, &lp->curpos);
	VecSub(lp->curpos, *pos, dir);
	*dist = VecNormalize(dir);
}

JitteredMethodRegister(meth)
UserMethodType meth;
{
	if (iJitteredMethods)
		iJitteredMethods->user = meth;
}