#include <stdlib.h>
#include <math.h>
#include "constants.h"
#include "typedefs.h"
#include "globalvar.h"

int maksph(int surf, double r, double x, double y, double z)
{
	int size;
	o_sphere *sphere;

	size = sizeof(o_sphere);
	sphere = ((o_sphere *)malloc(size));
	object[nobject].id = nobject;
	object[nobject].objtyp = OTYPSPHERE;
	object[nobject].surfnum = surf;
	object[nobject].objptr.p_sphere = sphere;
	sphere->r = r;
	sphere->x = x;
	sphere->y = y;
	sphere->z = z;
	return 0;
}

double intsph(t_3d *pos, t_3d *ray, t_object *obj)
{
	double b, c, D, s;
	double xadj, yadj, zadj;
	o_sphere *sph;

	sph = obj->objptr.p_sphere;

	/* translate ray origin to object's space */
	xadj = pos->x - sph->x;
	yadj = pos->y - sph->y;
	zadj = pos->z - sph->z;

	/* solve quadratic equation */
	b = xadj * ray->x + yadj * ray->y + zadj * ray->z;
	c = xadj * xadj + yadj * yadj + zadj * zadj - sph->r * sph->r;

	/* not sure why xadj is calculated, this should work: */
	/* b = pos->x * ray->x + pos->y * ray->y + pos->z * ray->z; */
	/* c = pos->x * pos->x + pos->y * pos->y + pos->z * pos->z - sph->r * sph->r; */

	D = b * b - c;
	
	if (D < 0) return 0.0;
	s = -b - sqrt(D);
	if (s > 0) return s;
	s = -b + sqrt(D);
	if (s > 0) return s;
	return 0;
}

int nrmsph(t_3d *pos, t_object *obj, t_3d *nrm)
{
	o_sphere *sph;
	sph = obj->objptr.p_sphere;
	nrm->x = (pos->x - sph->x) / sph->r;
	nrm->y = (pos->y - sph->y) / sph->r;
	nrm->z = (pos->z - sph->z) / sph->r;
	return 0;
}