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ben-scans/solidify/matrix.h
Werner Almesberger 898970b3dd Instead of performing the tranformations stepwise for each point, pre-calculate
them once.

- solidify/matrix.h, solidify/matrix.c: 2D matrix operations
- solidify/Makefile (OBJS): added matrix.o
- solidify/face.h (struct matrix): moved to solidify/matrix.h
- solidify/overlap.c (point, merge_matrix, draw_map): precalculate a single
  vA+b transformation instead of stepwise transforming the vector inside
  the loop
- solidify/overlap.c (do_shift): now that the math is right (or at least
  better), reverse the shift
2010-09-24 16:42:36 -03:00

46 lines
1.1 KiB
C

/*
* matrix.h - 2D matrix operations
*
* 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 MATRIX_H
#define MATRIX_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];
};
void matrix_identity(struct matrix *m);
void matrix_invert(const double m[2][2], double res[2][2]);
void matrix_mult(double a[2][2], double b[2][2], double res[2][2]);
void matrix_multv(const double v[2], double m[2][2], double res[2]);
void matrix_copy(double from[2][2], double to[2][2]);
static inline void matrix_map(int x, int y, const struct matrix *m,
double *res_x, double *res_y)
{
*res_x = x*m->a[0][0]+y*m->a[0][1]+m->b[0];
*res_y = x*m->a[1][0]+y*m->a[1][1]+m->b[1];
}
#endif /* !MATRIX_H */