#include <u.h>#include <libc.h>#include <draw.h>#include <memdraw.h>#include <geometry.h> #include "scene.h" Obj *newplane(Point3 p, Point3 n){	Obj *plane; 	plane = malloc(sizeof(Obj));	if(plane == nil)		exits("malloc"); 	plane->type = PLANE;	plane->p = p;	plane->n = n;	plane->next = nil;	plane->chld = nil; 	return plane;} Hitplanehit(Obj *plane, Point3 e, Point3 d){	double denom, intersect;	Point3 dist;	Hit hit;	int x; 	denom = dot3(d, plane->n);	if(denom == 0)		goto nohit; 	dist = sub3(plane->p, e);	intersect = dot3(dist, plane->n)/denom; 	if(intersect <= 0)		goto nohit; 	hit.d = intersect;	hit.p = add3(e, mul3(d, intersect));	hit.n = plane->n;	hit.ie = e;	hit.id = mul3(d, hit.d);	hit.o = plane; 	x = dist3(plane->p, hit.p) * 100;	if(x % 20 > 10)		hit.c = (Colour){0.75, 0.5, 0.25};	else		hit.c = (Colour){0.25, 0.5, 0.75}; 	return hit;nohit:	hit.d = 0;	return hit;}