#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "render.h"


void FixPart(PG_OBJECTPART *part,PG_OBJECT *obj);
void FixPoly(PG_POLYGON *poly,PG_VECTOR *points,PG_VECTOR *norm);

void FixNorms(PG_OBJECT *obj)
{
int i;
	for (i=0;i<obj->nparts;i++) {
		FixPart(&(obj->parts[i]),obj);		
	}
	for (i=0;i<obj->nobjects;i++) {
		FixNorms(obj->objects[i]);
	}
	
}


void FixPart(PG_OBJECTPART *part,PG_OBJECT *obj)
{
int i;
	for (i=0;i<part->npolys;i++) {
		FixPoly(&(part->polys[i]),part->points,&(part->norms[i]));		
	}
	for (i=0;i<obj->nwindows;i++) {
		FixPoly(&(part->windows[i]),part->points,&(part->norms[i+part->npolys]));
	}
}

#define vecsub(vd,va,vb) \
	(vd).x=(va).x-(vb).x;\
	(vd).y=(va).y-(vb).y;\
	(vd).z=(va).z-(vb).z;

#define length(v) sqrt(dot(v,v))


void FixPoly(PG_POLYGON *poly,PG_VECTOR *points,PG_VECTOR *norm)
{
PG_VECTOR tnorm,v1,v2;
float t;
int i,j;
	for (i=1;i<poly->n;i++) {
		for (j=i+1;j<poly->n;j++) {
			vecsub(v1,points[poly->points[0]],points[poly->points[i]]);
			vecsub(v2,points[poly->points[0]],points[poly->points[j]]);
			cross(tnorm,v1,v2);
			t=length(tnorm);
			if (t>length(v1)*length(v2)/20.0) {
				if (dot(tnorm,*norm)<0) {
					t=-t;
				}
				norm->x=tnorm.x/t;
				norm->y=tnorm.y/t;
				norm->z=tnorm.z/t;
				if (norm->y<0)
					puts("negative");
				printf("newnorm: %f %f %f\n",norm->x,norm->y,norm->z);
				return;
			}
		}
	}
	puts("error: couldn't check normal.");
}