#include <u.h>#include <libc.h>#include <draw.h>#include <memdraw.h>#include <geometry.h> #include "scene.h" Bboxspherebb(Point3 pos, double r){	Bbox b; 	b.min.x = pos.x - r;	b.min.y = pos.y - r;	b.min.z = pos.z - r;	b.min.w = 1; 	b.max.x = pos.x + r;	b.max.y = pos.y + r;	b.max.z = pos.z + r;	b.max.w = 1; 	return b;} Obj *newsphere(Point3 pos, double r){	Obj *sphere; 	sphere = malloc(sizeof(Obj));	if(sphere == nil)		exits("malloc"); 	sphere->type = SPHERE;	sphere->p = pos;	sphere->n = (Point3){0, 0, 0, 1};	sphere->r = r;	sphere->next = nil;	sphere->chld = nil;	sphere->Bbox = spherebb(pos, r); 	return sphere;} Hitspherehit(Obj *sphere, Point3 e, Point3 d){	Point3 ec;	Hit hit;	double discrim;	double smallterm;	double root;	double dd;	double numerator; 	ec = sub3(e, sphere->p);	smallterm = -dot3(d, ec); 	dd = dot3(d, d);	discrim = pow(dot3(d, ec), 2) - dd * (dot3(ec, ec) - pow(sphere->r, 2)); 	if(discrim < 0)		goto nohit; 	root = sqrt(discrim); 	numerator = smallterm + root;	if(smallterm - root < numerator && smallterm - root > 0)		numerator = smallterm - root; 	hit.d = numerator / dd;	hit.p = add3(e, mul3(d, hit.d));	hit.n = mul3(sub3(hit.p, sphere->p), 2);	hit.ie = e;	hit.id = mul3(d, hit.d);	hit.o = sphere;	hit.c = (Colour){0, 1, 0}; 	return hit;nohit:	hit.d = 0;	return hit;}