/*
 * face.h - Data structure and handling of one face of a part
 *
 * Written 2010 by Werner Almesberger
 * Copyright 2010 by Werner Almesberger
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#ifndef FACE_H
#define FACE_H

#include "array.h"


/*
 * 2D transformation:
 *
 * x' = x*a[0][0]+y*a[0][1]+b[0]
 * y' = x*a[1][0]+y*a[1][1]+b[1]
 */


struct matrix {
	double a[2][2];
	double b[2];
};

struct face {
	struct array *a;
	int sx, sy;	/* size */
	int z_ref;
	double fx, fy;	/* inclination factor */
	struct matrix m;
};


static inline double face_z0(const struct face *f, int x, int y)
{
	return f->z_ref+f->fx*(x-f->sx/2)+f->fy*(y-f->sy/2);
}


struct face *read_face(const char *name);

#endif /* FACE_H */